# Patent

## Title
Polypeptides having xylanase activity and polynucleotides encoding same

## Abstract

The present invention relates to isolated polypeptides having xylanase activity, catalytic domains, carbohydrate binding modules and polynucleotides encoding the polypeptides, catalytic domains or carbohydrate binding modules. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides, catalytic domains or carbohydrate binding modules.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional application of U.S. application Ser. No. 14/890,567 filed on Nov. 11, 2015, now U.S. Pat. No. 9,556,465, which is a 35 U.S.C. §371 national application of PCT/US2014/037429 filed on May 9, 2014 and claims priority or the benefit under 35 U.S.C. §119 of U.S. provisional application Ser. No. 61/821,905 filed May 10, 2013, the contents of which are fully incorporated herein by reference.


REFERENCE TO A SEQUENCE LISTING
This application contains a Sequence Listing in computer readable form, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to polypeptides having xylanase activity, catalytic domains, and carbohydrate binding modules, and polynucleotides encoding the polypeptides, catalytic domains, and carbohydrate binding modules. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides, catalytic domains, and carbohydrate binding modules.
Description of the Related Art
Lignocellulose, the world's largest renewable biomass resource, is composed mainly of lignin, cellulose, and hemicellulose, of which a large part of the latter is xylan. Xylanases (e.g., endo-1,4-beta-xylanase, EC 3.2.1.8) hydrolyze internal β-1,4-xylosidic linkages in xylan to produce smaller molecular weight xylose and xylo-oligomers. Xylans are polysaccharides formed from 1,4-β-glycoside-linked D-xylopyranoses.
Cellulose is a polymer of the simple glucose covalently linked by beta-1,4-bonds. Many microorganisms produce enzymes that hydrolyze beta-linked glucans. These enzymes include endoglucanases, cellobiohydrolases, and beta-glucosidases. Endoglucanases digest the cellulose polymer at random locations, opening it to attack by cellobiohydrolases. Cellobiohydrolases sequentially release molecules of cellobiose from the ends of the cellulose polymer. Cellobiose is a water-soluble beta-1,4-linked dimer of glucose. Beta-glucosidases hydrolyze cellobiose to glucose. Once the cellulose is converted to glucose, the glucose is easily fermented by yeast into ethanol.
The conversion of lignocellulosic feedstocks into ethanol has the advantages of the ready availability of large amounts of feedstock, the desirability of avoiding burning or land filling the materials, and the cleanliness of the ethanol fuel. Wood, agricultural residues, herbaceous crops, and municipal solid wastes have been considered as feedstocks for ethanol production. These materials primarily consist of cellulose, hemicellulose, and lignin. Once the cellulose is converted to glucose, the glucose is easily fermented by yeast into ethanol.
Yoshioka et al., 1981, Agric. Biol. Chem. 45(3): 579-586, disclose production and characterization of a thermostable xylanase from Talaromyces byssochlamydoides YH-50. Yoshioka et al., 1981, Agric. Biol. Chem. 45(11): 2425-2432, disclose purification and properties of a thermostable xylanase from Talaromyces byssochlamydoides YH-50. Hayashida et al., 1988, Methods In Enzymology 160: 675-678, disclose a Talaromyces byssochlamydoides xylanase. WO 02/24926 discloses a Talaromyces emersonii GH10 xylanase (GENESEQP:AAU99346).
There is a need in the art to improve cellulolytic enzyme compositions through supplementation with additional enzymes to increase efficiency and to provide cost-effective enzyme solutions for degradation of lignocellulose.
The present invention provides polypeptides having xylanase activity and polynucleotides encoding the polypeptides.
SUMMARY OF THE INVENTION
The present invention relates to isolated polypeptides having xylanase activity selected from the group consisting of:
(a) a polypeptide having at least 90% sequence identity to the mature polypeptide of SEQ ID NO: 2, or to the mature polypeptide of SEQ ID NO: 6;
(b) a polypeptide encoded by a polynucleotide having at least 90% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1 or the cDNA sequence thereof, or to the mature polypeptide coding sequence of SEQ ID NO: 5 or the cDNA sequence thereof;
(c) a variant of the mature polypeptide of SEQ ID NO: 2, or of the mature polypeptide of SEQ ID NO: 6 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions; and
(d) a fragment of the polypeptide of (a), (b), or (c) that has xylanase activity.
The present invention also relates to isolated polypeptides comprising a catalytic domain selected from the group consisting of:
(a) a catalytic domain having at least 90% sequence identity to amino acids 24 to 340 of SEQ ID NO: 2 or to amino acids 24 to 341 of SEQ ID NO: 6;
(b) a catalytic domain encoded by a polynucleotide having at least 90% sequence identity to nucleotides 157 to 1339 of SEQ ID NO: 1 or the cDNA sequence thereof, or having at least 90% sequence identity to nucleotides 151 to 1387 of SEQ ID NO: 5 or the cDNA sequence thereof;
(c) a variant of amino acids 24 to 340 of SEQ ID NO: 2, or of acids 24 to 341 of SEQ ID NO: 6 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions; and
(d) a fragment of the catalytic domain of (a), (b), or (c) that has xylanase activity.
The present invention also relates to isolated polypeptides comprising a carbohydrate binding module selected from the group consisting of:
(a) a carbohydrate binding module having at least 90% sequence identity to amino acids 373 to 406 of SEQ ID NO: 2 or having at least 90% sequence identity to amino acids 371 to 406 of SEQ ID NO: 6;
(b) a carbohydrate binding module encoded by a polynucleotide having at least 90% sequence identity to nucleotides 1436 to 1537 of SEQ ID NO: 1 or the cDNA sequence thereof, or encoded by a polynucleotide having at least 90% sequence identity to nucleotides 1480-1587 of SEQ ID NO: 5;
(c) a variant of amino acids 373 to 406 of SEQ ID NO: 2, or of amino acids 371 to 406 of SEQ ID NO: 6, comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions; and
(d) a fragment of the carbohydrate binding module of (a), (b), or (c) that has binding activity.
The present invention also relates to isolated polynucleotides encoding the polypeptides of the present invention; nucleic acid constructs, recombinant expression vectors, and recombinant host cells comprising the polynucleotides; and methods of producing the polypeptides.
The present invention also relates to processes for degrading a cellulosic or xylan-containing material, comprising: treating the cellulosic or xylan-containing material with an enzyme composition in the presence of a polypeptide having xylanase activity of the present invention. In one aspect, the processes further comprise recovering the degraded cellulosic or xylan-containing material.
The present invention also relates to processes of producing a fermentation product, comprising: (a) saccharifying a cellulosic or xylan-containing material with an enzyme composition in the presence of a polypeptide having xylanase activity of the present invention; (b) fermenting the saccharified cellulosic or xylan-containing material with one or more (e.g., several) fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
The present invention also relates to processes of fermenting a cellulosic or xylan-containing material, comprising: fermenting the cellulosic or xylan-containing material with one or more (e.g., several) fermenting microorganisms, wherein the cellulosic or xylan-containing material is saccharified with an enzyme composition in the presence of a polypeptide having xylanase activity of the present invention. In one aspect, the fermenting of the cellulosic or xylan-containing material produces a fermentation product. In another aspect, the processes further comprise recovering the fermentation product from the fermentation.
The present invention also relates to an isolated polynucleotide encoding a signal peptide comprising or consisting of amino acids 1 to 23 of SEQ ID NO: 2, or a signal peptide comprising or consisting of amino acids 1 to 23 of SEQ ID NO: 6, which is operably linked to a gene encoding a protein, wherein the protein is foreign to the signal peptide; nucleic acid constructs, expression vectors, and recombinant host cells comprising the polynucleotides; and methods of producing a protein.



BRIEF DESCRIPTION OF THE FIGURE
The FIGURE shows hydrolysis results of washed ground-sieved alkaline pretreated corn cobs (GS-APCC) as a substrate at pH 4.0 from 50° C. to 65° C. by the Rasamsonia byssochiamydoides GH10 xylanase (P24GTR) supplemented with Talaromyces emersonii GH3 beta-xylosidase.



DEFINITIONS
Acetylxylan esterase: The term “acetylxylan esterase” means a carboxylesterase (EC 3.1.1.72) that catalyzes the hydrolysis of acetyl groups from polymeric xylan, acetylated xylose, acetylated glucose, alpha-napthyl acetate, and p-nitrophenyl acetate. Acetylxylan esterase activity is preferably determined using 0.5 mM p-nitrophenylacetate as substrate in 50 mM sodium acetate pH 5.0 containing 0.01% TWEENTM 20 (polyoxyethylene sorbitan monolaurate). One unit of acetylxylan esterase is defined as the amount of enzyme capable of releasing 1 μmole of p-nitrophenolate anion per minute at pH 5, 25° C.
Allelic variant: The term “allelic variant” means any of two or more alternative forms of a gene occupying the same chromosomal locus. Allelic variation arises naturally through mutation, and may result in polymorphism within populations. Gene mutations can be silent (no change in the encoded polypeptide) or may encode polypeptides having altered amino acid sequences. An allelic variant of a polypeptide is a polypeptide encoded by an allelic variant of a gene.
Alpha-L-arabinofuranosidase: The term “alpha-L-arabinofuranosidase” means an alpha-L-arabinofuranoside arabinofuranohydrolase (EC 3.2.1.55) that catalyzes the hydrolysis of terminal non-reducing alpha-L-arabinofuranoside residues in alpha-L-arabinosides. The enzyme acts on alpha-L-arabinofuranosides, alpha-L-arabinans containing (1,3)- and/or (1,5)-linkages, arabinoxylans, and arabinogalactans. Alpha-L-arabinofuranosidase is also known as arabinosidase, alpha-arabinosidase, alpha-L-arabinosidase, alpha-arabinofuranosidase, polysaccharide alpha-L-arabinofuranosidase, alpha-L-arabinofuranoside hydrolase, L-arabinosidase, or alpha-L-arabinanase. Alpha-L-arabinofuranosidase activity is preferably determined using 5 mg of medium viscosity wheat arabinoxylan (Megazyme International Ireland, Ltd., Bray, Co. Wicklow, Ireland) per ml of 100 mM sodium acetate pH 5 in a total volume of 200 μl for 30 minutes at 40° C. followed by arabinose analysis by AMINEX® HPX-87H column chromatography (Bio-Rad Laboratories, Inc., Hercules, Calif., USA).
Alpha-glucuronidase: The term “alpha-glucuronidase” means an alpha-D-glucosiduronate glucuronohydrolase (EC 3.2.1.139) that catalyzes the hydrolysis of an alpha-D-glucuronoside to D-glucuronate and an alcohol. Alpha-glucuronidase activity is preferably determined according to de Vries, 1998, J. Bacteriol. 180: 243-249. One unit of alpha-glucuronidase equals the amount of enzyme capable of releasing 1 μmole of glucuronic or 4-O-methylglucuronic acid per minute at pH 5, 40° C.
Beta-glucosidase: The term “beta-glucosidase” means a beta-D-glucoside glucohydrolase (E.C. 3.2.1.21) that catalyzes the hydrolysis of terminal non-reducing beta-D-glucose residues with the release of beta-D-glucose. Beta-glucosidase activity is preferably determined using p-nitrophenyl-beta-D-glucopyranoside as substrate according to the procedure of Venturi et al., 2002, J. Basic Microbiol. 42: 55-66. One unit of beta-glucosidase is defined as 1.0 μmole of p-nitrophenolate anion produced per minute at 25° C., pH 4.8 from 1 mM p-nitrophenyl-beta-D-glucopyranoside as substrate in 50 mM sodium citrate containing 0.01% TWEEN® 20.
Beta-xylosidase: The term “beta-xylosidase” means a beta-D-xyloside xylohydrolase (E.C. 3.2.1.37) that catalyzes the exo-hydrolysis of short beta (1→4)-xylooligosaccharides to remove successive D-xylose residues from non-reducing termini. Beta-xylosidase activity is preferably determined using 1 mM p-nitrophenyl-beta-D-xyloside as substrate in 100 mM sodium citrate containing 0.01% TWEEN® 20 at pH 5, 40° C. One unit of beta-xylosidase is defined as 1.0 μmole of p-nitrophenolate anion produced per minute at 40° C., pH 5 from 1 mM p-nitrophenyl-beta-D-xyloside in 100 mM sodium citrate containing 0.01% TWEEN® 20.
cDNA: The term “cDNA” means a DNA molecule that can be prepared by reverse transcription from a mature, spliced, mRNA molecule obtained from a eukaryotic or prokaryotic cell. cDNA lacks intron sequences that may be present in the corresponding genomic DNA. The initial, primary RNA transcript is a precursor to mRNA that is processed through a series of steps, including splicing, before appearing as mature spliced mRNA.
Carbohydrate binding module: The term “carbohydrate binding module” means the region within a carbohydrate-active enzyme that provides carbohydrate-binding activity (Boraston et al., 2004, Biochem. J. 383: 769-781). A majority of known carbohydrate binding modules (CBMs) are contiguous amino acid sequences with a discrete fold. The carbohydrate binding module (CBM) is typically found either at the N-terminal or at the C-terminal extremity of an enzyme. Some CBMs are known to have specificity for cellulose.
Catalytic domain: The term “catalytic domain” means the region of an enzyme containing the catalytic machinery of the enzyme.
Cellobiohydrolase: The term “cellobiohydrolase” means a 1,4-beta-D-glucan cellobiohydrolase (E.C. 3.2.1.91 and E.C. 3.2.1.176) that catalyzes the hydrolysis of 1,4-beta-D-glucosidic linkages in cellulose, cellooligosaccharides, or any beta-1,4-linked glucose containing polymer, releasing cellobiose from the reducing end (cellobiohydrolase I) or non-reducing end (cellobiohydrolase II) of the chain (Teeri, 1997, Trends in Biotechnology 15: 160-167; Teeri et al., 1998, Biochem. Soc. Trans. 26: 173-178). Cellobiohydrolase activity is preferably determined according to the procedures described by Lever et al., 1972, Anal. Biochem. 47: 273-279; van Tilbeurgh et al., 1982, FEBS Letters 149: 152-156; van Tilbeurgh and Claeyssens, 1985, FEBS Letters 187: 283-288; and Tomme et al., 1988, Eur. J. Biochem. 170: 575-581.
Cellulolytic enzyme or cellulase: The term “cellulolytic enzyme” or “cellulase” means one or more (e.g., several) enzymes that hydrolyze a cellulosic material. Such enzymes include endoglucanase(s), cellobiohydrolase(s), beta-glucosidase(s), or combinations thereof. The two basic approaches for measuring cellulolytic enzyme activity include: (1) measuring the total cellulolytic activity, and (2) measuring the individual cellulolytic activities (endoglucanases, cellobiohydrolases, and beta-glucosidases) as reviewed in Zhang et al., 2006, Biotechnology Advances 24: 452-481. Total cellulolytic activity is usually measured using insoluble substrates, including Whatman No 1 filter paper, microcrystalline cellulose, bacterial cellulose, algal cellulose, cotton, pretreated lignocellulose, etc. The most common total cellulolytic activity assay is the filter paper assay using Whatman No 1 filter paper as the substrate. The assay was established by the International Union of Pure and Applied Chemistry (IUPAC) (Ghose, 1987, Pure Appl. Chem. 59: 257-68).
For purposes of the present invention, cellulolytic enzyme activity is preferably determined by measuring the increase in hydrolysis of a cellulosic material by cellulolytic enzyme(s) under the following conditions: 1-50 mg of cellulolytic enzyme protein/g of cellulose in PCS (or other pretreated cellulosic material) for 3-7 days at a suitable temperature, such as 40° C.-80° C., e.g., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH, such as 4-9, e.g., 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, or 8.5, compared to a control hydrolysis without addition of cellulolytic enzyme protein. Typical conditions are 1 ml reactions, washed or unwashed PCS, 5% insoluble solids, 50 mM sodium acetate pH 5, 1 mM MnSO4, 50° C., 55° C., or 60° C., 72 hours, sugar analysis by AMINEX® HPX-87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA).
Cellulosic material: The term “cellulosic material” means any material containing cellulose. The predominant polysaccharide in the primary cell wall of biomass is cellulose, the second most abundant is hemicellulose, and the third is pectin. The secondary cell wall, produced after the cell has stopped growing, also contains polysaccharides and is strengthened by polymeric lignin covalently cross-linked to hemicellulose. Cellulose is a homopolymer of anhydrocellobiose and thus a linear beta-(1-4)-D-glucan, while hemicelluloses include a variety of compounds, such as xylans, xyloglucans, arabinoxylans, and mannans in complex branched structures with a spectrum of substituents. Although generally polymorphous, cellulose is found in plant tissue primarily as an insoluble crystalline matrix of parallel glucan chains. Hemicelluloses usually hydrogen bond to cellulose, as well as to other hemicelluloses, which help stabilize the cell wall matrix.
Cellulose is generally found, for example, in the stems, leaves, hulls, husks, and cobs of plants or leaves, branches, and wood of trees. The cellulosic material can be, but is not limited to, agricultural residue, herbaceous material (including energy crops), municipal solid waste, pulp and paper mill residue, waste paper, and wood (including forestry residue) (see, for example, Wiselogel et al., 1995, in Handbook on Bioethanol (Charles E. Wyman, editor), pp. 105-118, Taylor & Francis, Washington D.C.; Wyman, 1994, Bioresource Technology 50: 3-16; Lynd, 1990, Applied Biochemistry and Biotechnology 24/25: 695-719; Mosier et al., 1999, Recent Progress in Bioconversion of Lignocellulosics, in Advances in Biochemical Engineering/Biotechnology, T. Scheper, managing editor, Volume 65, pp. 23-40, Springer-Verlag, New York). It is understood herein that the cellulose may be in the form of lignocellulose, a plant cell wall material containing lignin, cellulose, and hemicellulose in a mixed matrix. In a preferred aspect, the cellulosic material is any biomass material. In another preferred aspect, the cellulosic material is lignocellulose, which comprises cellulose, hemicelluloses, and lignin.
In one aspect, the cellulosic material is agricultural residue, herbaceous material (including energy crops), municipal solid waste, pulp and paper mill residue, waste paper, or wood (including forestry residue).
In another aspect, the cellulosic material is arundo, bagasse, bamboo, corn cob, corn fiber, corn stover, miscanthus, rice straw, switchgrass, or wheat straw.
In another aspect, the cellulosic material is aspen, eucalyptus, fir, pine, poplar, spruce, or willow.
In another aspect, the cellulosic material is algal cellulose, bacterial cellulose, cotton linter, filter paper, microcrystalline cellulose (e.g., AVICEL®), or phosphoric-acid treated cellulose.
In another aspect, the cellulosic material is an aquatic biomass. As used herein the term “aquatic biomass” means biomass produced in an aquatic environment by a photosynthesis process. The aquatic biomass can be algae, emergent plants, floating-leaf plants, or submerged plants.
The cellulosic material may be used as is or may be subjected to pretreatment, using conventional methods known in the art, as described herein. In a preferred aspect, the cellulosic material is pretreated.
Coding sequence: The term “coding sequence” means a polynucleotide, which directly specifies the amino acid sequence of a polypeptide. The boundaries of the coding sequence are generally determined by an open reading frame, which begins with a start codon such as ATG, GTG, or TTG and ends with a stop codon such as TAA, TAG, or TGA. The coding sequence may be a genomic DNA, cDNA, synthetic DNA, or a combination thereof.
Control sequences: The term “control sequences” means nucleic acid sequences necessary for expression of a polynucleotide encoding a mature polypeptide of the present invention. Each control sequence may be native (i.e., from the same gene) or foreign (i.e., from a different gene) to the polynucleotide encoding the polypeptide or native or foreign to each other. Such control sequences include, but are not limited to, a leader, polyadenylation sequence, propeptide sequence, promoter, signal peptide sequence, and transcription terminator. At a minimum, the control sequences include a promoter, and transcriptional and translational stop signals. The control sequences may be provided with linkers for the purpose of introducing specific restriction sites facilitating ligation of the control sequences with the coding region of the polynucleotide encoding a polypeptide.
Endoglucanase: The term “endoglucanase” means an endo-1,4-(1,3;1,4)-beta-D-glucan 4-glucanohydrolase (E.C. 3.2.1.4) that catalyzes endohydrolysis of 1,4-beta-D-glycosidic linkages in cellulose, cellulose derivatives (such as carboxymethyl cellulose and hydroxyethyl cellulose), lichenin, beta-1,4 bonds in mixed beta-1,3 glucans such as cereal beta-D-glucans or xyloglucans, and other plant material containing cellulosic components. Endoglucanase activity can be determined by measuring reduction in substrate viscosity or increase in reducing ends determined by a reducing sugar assay (Zhang et al., 2006, Biotechnology Advances 24: 452-481). Endoglucanase activity is preferably determined using carboxymethyl cellulose (CMC) as substrate according to the procedure of Ghose, 1987, Pure and Appl. Chem. 59: 257-268, at pH 5, 40° C.
Expression: The term “expression” includes any step involved in the production of a polypeptide including, but not limited to, transcription, post-transcriptional modification, translation, post-translational modification, and secretion.
Expression vector: The term “expression vector” means a linear or circular DNA molecule that comprises a polynucleotide encoding a polypeptide and is operably linked to control sequences that provide for its expression.
Family 10 glycoside hydrolase: The term “Family 10 glycoside hydrolase” or “Family GH10” or “GH10” means a polypeptide falling into the glycoside hydrolase Family 10 according to Henrissat, 1991, A classification of glycosyl hydrolases based on amino-acid sequence similarities, Biochem. J. 280: 309-316, and Henrissat and Bairoch, 1996, Updating the sequence-based classification of glycosyl hydrolases, Biochem. J. 316: 695-696.
Family 61 glycoside hydrolase: The term “Family 61 glycoside hydrolase” or “Family GH61” or “GH61” means a polypeptide falling into the glycoside hydrolase Family 61 according to Henrissat, 1991, Biochem. J. 280: 309-316, and Henrissat and Bairoch, 1996, Biochem. J. 316: 695-696. The enzymes in this family were originally classified as a glycoside hydrolase family based on measurement of very weak endo-1,4-beta-D-glucanase activity in one family member. The GH61s have recently been classified as lytic polysaccharide monooxygenases (Quinlan et al., 2011, Proc. Natl. Acad. Sci. USA 208: 15079-15084; Phillips et al., 2011, ACS Chem. Biol. 6: 1399-1406; Lin et al., 2012, Structure 20: 1051-1061).
Feruloyl esterase: The term “feruloyl esterase” means a 4-hydroxy-3-methoxycinnamoyl-sugar hydrolase (EC 3.1.1.73) that catalyzes the hydrolysis of 4-hydroxy-3-methoxycinnamoyl (feruloyl) groups from esterified sugar, which is usually arabinose in natural biomass substrates, to produce ferulate (4-hydroxy-3-methoxycinnamate). Feruloyl esterase is also known as ferulic acid esterase, hydroxycinnamoyl esterase, FAE-III, cinnamoyl ester hydrolase, FAEA, cinnAE, FAE-I, or FAE-II. Feruloyl esterase activity is preferably determined using 0.5 mM p-nitrophenylferulate as substrate in 50 mM sodium acetate pH 5.0. One unit of feruloyl esterase equals the amount of enzyme capable of releasing 1 μmole of p-nitrophenolate anion per minute at pH 5, 25° C.
Fragment: The term “fragment” means a polypeptide having one or more (e.g., several) amino acids absent from the amino and/or carboxyl terminus of a mature polypeptide main; wherein the fragment has xylanase activity. In one aspect, a fragment contains at least 320 amino acid residues, e.g., at least 340 amino acid residues or at least 360 amino acid residues of SEQ ID NO: 2 or of SEQ ID NO: 6.
Hemicellulolytic enzyme or hemicellulase: The term “hemicellulolytic enzyme” or “hemicellulase” means one or more (e.g., several) enzymes that hydrolyze a hemicellulosic material. See, for example, Shallom and Shoham, 2003, Current Opinion In Microbiology 6(3): 219-228). Hemicellulases are key components in the degradation of plant biomass. Examples of hemicellulases include, but are not limited to, an acetylmannan esterase, an acetylxylan esterase, an arabinanase, an arabinofuranosidase, a coumaric acid esterase, a feruloyl esterase, a galactosidase, a glucuronidase, a glucuronoyl esterase, a mannanase, a mannosidase, a xylanase, and a xylosidase. The substrates for these enzymes, hemicelluloses, are a heterogeneous group of branched and linear polysaccharides that are bound via hydrogen bonds to the cellulose microfibrils in the plant cell wall, crosslinking them into a robust network. Hemicelluloses are also covalently attached to lignin, forming together with cellulose a highly complex structure. The variable structure and organization of hemicelluloses require the concerted action of many enzymes for its complete degradation. The catalytic modules of hemicellulases are either glycoside hydrolases (GHs) that hydrolyze glycosidic bonds, or carbohydrate esterases (CEs), which hydrolyze ester linkages of acetate or ferulic acid side groups. These catalytic modules, based on homology of their primary sequence, can be assigned into GH and CE families. Some families, with an overall similar fold, can be further grouped into clans, marked alphabetically (e.g., GH-A). A most informative and updated classification of these and other carbohydrate active enzymes is available in the Carbohydrate-Active Enzymes (CAZy) database. Hemicellulolytic enzyme activities can be measured according to Ghose and Bisaria, 1987, Pure & Appl. Chem. 59: 1739-1752, at a suitable temperature, e.g., 50° C., 55° C., or 60° C., and pH, e.g., 4.5, 5.0 or 5.5.
High stringency conditions: The term “high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 50% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 65° C.
Host cell: The term “host cell” means any cell type that is susceptible to transformation, transfection, transduction, or the like with a nucleic acid construct or expression vector comprising a polynucleotide of the present invention. The term “host cell” encompasses any progeny of a parent cell that is not identical to the parent cell due to mutations that occur during replication.
Isolated: The term “isolated” means a substance in a form or environment that does not occur in nature. Non-limiting examples of isolated substances include (1) any non-naturally occurring substance, (2) any substance including, but not limited to, any enzyme, variant, nucleic acid, protein, peptide or cofactor, that is at least partially removed from one or more or all of the naturally occurring constituents with which it is associated in nature; (3) any substance modified by the hand of man relative to that substance found in nature; or (4) any substance modified by increasing the amount of the substance relative to other components with which it is naturally associated (e.g., recombinant production in a host cell; multiple copies of a gene encoding the substance; and use of a stronger promoter than the promoter naturally associated with the gene encoding the substance).
Low stringency conditions: The term “low stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 25% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 50° C.
Mature polypeptide: The term “mature polypeptide” means a polypeptide in its final form following translation and any post-translational modifications, such as N-terminal processing, C-terminal truncation, glycosylation, phosphorylation, etc. In one aspect, the mature polypeptide is amino acids 24 to 406 of SEQ ID NO: 2 (P24GTR) based on the SignalP program (Nielsen et al., 1997, Protein Engineering 10: 1-6) that predicts amino acids 1 to 23 of SEQ ID NO: 2 are a signal peptide. In another aspect, the mature polypeptide is amino acids 24 to 406 of SEQ ID NO: 6 (P34RRZ) based on the SignalP program (Nielsen et al., 1997, Protein Engineering 10: 1-6) that predicts amino acids 1 to 23 of SEQ ID NO: 6 are a signal peptide. It is known in the art that a host cell may produce a mixture of two of more different mature polypeptides (i.e., with a different C-terminal and/or N-terminal amino acid) expressed by the same polynucleotide.
Mature polypeptide coding sequence: The term “mature polypeptide coding sequence” means a polynucleotide that encodes a mature polypeptide having xylanase activity. In one aspect, the mature polypeptide coding sequence is nucleotides 157 to 1537 of SEQ ID NO: 1 (D82RVA) or the cDNA sequence thereof based on the SignalP program (Nielsen et al., 1997, supra) that predicts nucleotides 1 to 156 of SEQ ID NO: 1 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 151 to 1587 of SEQ ID NO: 5 (D24EPN) or the cDNA sequence thereof based on the SignalP program (Nielsen et al., 1997, supra) that predicts nucleotides 1 to 150 of SEQ ID NO: 5 encode a signal peptide.
Medium stringency conditions: The term “medium stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 35% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 55° C.
Medium-high stringency conditions: The term “medium-high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 35% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 60° C.
Nucleic acid construct: The term “nucleic acid construct” means a nucleic acid molecule, either single- or double-stranded, which is isolated from a naturally occurring gene or is modified to contain segments of nucleic acids in a manner that would not otherwise exist in nature or which is synthetic, which comprises one or more control sequences.
Operably linked: The term “operably linked” means a configuration in which a control sequence is placed at an appropriate position relative to the coding sequence of a polynucleotide such that the control sequence directs expression of the coding sequence.
Polypeptide having cellulolytic enhancing activity: The term “polypeptide having cellulolytic enhancing activity” means a GH61 polypeptide that catalyzes the enhancement of the hydrolysis of a cellulosic material by enzyme having cellulolytic activity. Cellulolytic enhancing activity is preferably determined by measuring the increase in reducing sugars or the increase of the total of cellobiose and glucose from the hydrolysis of a cellulosic material by cellulolytic enzyme under the following conditions: 1-50 mg of total protein/g of cellulose in pretreated corn stover (PCS), wherein total protein is comprised of 50-99.5% w/w cellulolytic enzyme protein and 0.5-50% w/w protein of a GH61 polypeptide for 1-7 days at a suitable temperature, such as 40° C.-80° C., e.g., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH, such as 4-9, e.g., 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, or 8.5, compared to a control hydrolysis with equal total protein loading without cellulolytic enhancing activity (1-50 mg of cellulolytic protein/g of cellulose in PCS).
In one aspect, GH61 polypeptide enhancing activity is determined using a mixture of CELLUCLAST® 1.5 L (Novozymes A/S, Bagsværd, Denmark) in the presence of 2-3% of total protein weight Aspergillus oryzae beta-glucosidase (recombinantly produced in Aspergillus oryzae according to WO 02/095014) or 2-3% of total protein weight Aspergillus fumigatus beta-glucosidase (recombinantly produced in Aspergillus oryzae as described in WO 02/095014) of cellulase protein loading is used as the source of the cellulolytic activity.
In another aspect, GH61 polypeptide enhancing activity is determined according to WO 2013/028928 for high temperature compositions.
The GH61 polypeptides having cellulolytic enhancing activity enhance the hydrolysis of a cellulosic material catalyzed by enzyme having cellulolytic activity by reducing the amount of cellulolytic enzyme required to reach the same degree of hydrolysis preferably at least 1.01-fold, e.g., at least 1.05-fold, at least 1.10-fold, at least 1.25-fold, at least 1.5-fold, at least 2-fold, at least 3-fold, at least 4-fold, at least 5-fold, at least 10-fold, or at least 20-fold.
Pretreated corn stover: The term “PCS” or “Pretreated Corn Stover” means a cellulosic material derived from corn stover by treatment with heat and dilute sulfuric acid, alkaline pretreatment, neutral pretreatment, or any pretreatment known in the art.
Sequence identity: The relatedness between two amino acid sequences or between two nucleotide sequences is described by the parameter “sequence identity”.
For purposes of the present invention, the sequence identity between two amino acid sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, J. Mol. Biol. 48: 443-453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000, Trends Genet. 16: 276-277), preferably version 3.0.0, 5.0.0 or later. The parameters used are gap open penalty of 10, gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. The output of Needle labeled “longest identity” (obtained using the −nobrief option) is used as the percent identity and is calculated as follows:

(Identical Residues×100)/(Length of Alignment−Total Number of Gaps in Alignment)

For purposes of the present invention, the sequence identity between two deoxyribonucleotide sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, supra) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000, supra), preferably version 5.0.0 or later. The parameters used are gap open penalty of 10, gap extension penalty of 0.5, and the EDNAFULL (EMBOSS version of NCBI NUC4.4) substitution matrix. The output of Needle labeled “longest identity” (obtained using the −nobrief option) is used as the percent identity and is calculated as follows:

(Identical Deoxyribonucleotides×100)/(Length of Alignment−Total Number of Gaps in Alignment)

Subsequence: The term “subsequence” means a polynucleotide having one or more (e.g., several) nucleotides absent from the 5′ and/or 3′ end of a mature polypeptide coding sequence; wherein the subsequence encodes a fragment having xylanase activity. In one aspect, a subsequence contains at least 960 nucleotides, e.g., at least 1020 nucleotides or at least 1080 nucleotides of SEQ ID NO: 1 or of SEQ ID NO: 5.
Variant: The term “variant” means a polypeptide having xylanase activity comprising an alteration, i.e., a substitution, insertion, and/or deletion, at one or more (e.g., several) positions. A substitution means replacement of the amino acid occupying a position with a different amino acid; a deletion means removal of the amino acid occupying a position; and an insertion means adding an amino acid adjacent to and immediately following the amino acid occupying a position.
Very high stringency conditions: The term “very high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 50% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 70° C.
Very low stringency conditions: The term “very low stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 25% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 45° C.
Xylan-containing material: The term “xylan-containing material” means any material comprising a plant cell wall polysaccharide containing a backbone of beta-(1-4)-linked xylose residues. Xylans of terrestrial plants are heteropolymers possessing a beta-(1-4)-D-xylopyranose backbone, which is branched by short carbohydrate chains. They comprise D-glucuronic acid or its 4-O-methyl ether, L-arabinose, and/or various oligosaccharides, composed of D-xylose, L-arabinose, D- or L-galactose, and D-glucose. Xylan-type polysaccharides can be divided into homoxylans and heteroxylans, which include glucuronoxylans, (arabino)glucuronoxylans, (glucurono)arabinoxylans, arabinoxylans, and complex heteroxylans. See, for example, Ebringerova et al., 2005, Adv. Polym. Sci. 186: 1-67.
In the processes of the present invention, any material containing xylan may be used. In a preferred aspect, the xylan-containing material is lignocellulose.
Xylan degrading activity or xylanolytic activity: The term “xylan degrading activity” or “xylanolytic activity” means a biological activity that hydrolyzes xylan-containing material. The two basic approaches for measuring xylanolytic activity include: (1) measuring the total xylanolytic activity, and (2) measuring the individual xylanolytic activities (e.g., endoxylanases, beta-xylosidases, arabinofuranosidases, alpha-glucuronidases, acetylxylan esterases, feruloyl esterases, and alpha-glucuronyl esterases). Recent progress in assays of xylanolytic enzymes was summarized in several publications including Biely and Puchard, 2006, Journal of the Science of Food and Agriculture 86(11): 1636-1647; Spanikova and Biely, 2006, FEBS Letters 580(19): 4597-4601; Herrmann et al., 1997, Biochemical Journal 321: 375-381.
Total xylan degrading activity can be measured by determining the reducing sugars formed from various types of xylan, including, for example, oat spelt, beechwood, and larchwood xylans, or by photometric determination of dyed xylan fragments released from various covalently dyed xylans. The most common total xylanolytic activity assay is based on production of reducing sugars from polymeric 4-O-methyl glucuronoxylan as described in Bailey et al., 1992, Interlaboratory testing of methods for assay of xylanase activity, Journal of Biotechnology 23(3): 257-270. Xylanase activity can also be determined with 0.2% AZCL-arabinoxylan as substrate in 0.01% TRITON® X-100 (4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol) and 200 mM sodium phosphate pH 6 at 37° C. One unit of xylanase activity is defined as 1.0 μmole of azurine produced per minute at 37° C., pH 6 from 0.2% AZCL-arabinoxylan as substrate in 200 mM sodium phosphate pH 6.
Xylan degrading activity is preferably determined by measuring the increase in hydrolysis of birchwood xylan (Sigma Chemical Co., Inc., St. Louis, Mo., USA) by xylan-degrading enzyme(s) under the following typical conditions: 1 ml reactions, 5 mg/ml substrate (total solids), 5 mg of xylanolytic protein/g of substrate, 50 mM sodium acetate pH 5, 50° C., 24 hours, sugar analysis using p-hydroxybenzoic acid hydrazide (PHBAH) assay as described by Lever, 1972, Anal. Biochem. 47: 273-279.
Xylanase: The term “xylanase” means a 1,4-beta-D-xylan-xylohydrolase (E.C. 3.2.1.8) that catalyzes the endohydrolysis of 1,4-beta-D-xylosidic linkages in xylans. Xylanase activity is preferably determined with 0.2% AZCL-arabinoxylan as substrate in 0.01% TRITON® X-100 and 200 mM sodium phosphate pH 6 at 37° C. One unit of xylanase activity is defined as 1.0 μmole of azurine produced per minute at 37° C., pH 6 from 0.2% AZCL-arabinoxylan as substrate in 200 mM sodium phosphate pH 6.
The polypeptides of the present invention have at least 20%, e.g., at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, and at least 100% of the xylanase activity of the mature polypeptide of SEQ ID NO: 2 or of the mature polypeptide of SEQ ID NO: 6.
DETAILED DESCRIPTION OF THE INVENTION
Polypeptides Having Xylanase Activity
In an embodiment, the present invention relates to isolated polypeptides having a sequence identity to the mature polypeptide of SEQ ID NO: 2 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have xylanase activity. In one aspect, the polypeptides differ by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 2.
In another embodiment, the present invention relates to isolated polypeptides having a sequence identity to the mature polypeptide of SEQ ID NO: 6 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have xylanase activity. In one aspect, the polypeptides differ by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 6.
A polypeptide of the present invention preferably comprises or consists of the amino acid sequence of SEQ ID NO: 2 or SEQ ID NO: 6, or an allelic variant thereof; or is a fragment thereof having xylanase activity. In another aspect, the polypeptide comprises or consists of the mature polypeptide of SEQ ID NO: 2. In another aspect, the polypeptide comprises or consists of amino acids 24 to 406 of SEQ ID NO: 2. In another aspect, the polypeptide comprises or consists of amino acids 24 to 406 of SEQ ID NO: 6.
In another embodiment, the present invention relates to an isolated polypeptide having xylanase activity encoded by a polynucleotide that hybridizes under very low stringency conditions, low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with (i) the mature polypeptide coding sequence of SEQ ID NO: 1 or of SEQ ID NO: 5, (ii) the cDNA sequence of SEQ ID NO: 1 or of SEQ ID NO: 5, or (iii) the full-length complement of (i) or (ii) (Sambrook et al., 1989, Molecular Cloning, A Laboratory Manual, 2d edition, Cold Spring Harbor, New York).
The polynucleotide of SEQ ID NO: 1 or SEQ ID NO: 5, or a subsequence thereof, as well as the polypeptide of SEQ ID NO: 2 or of SEQ ID NO: 6, the mature polypeptide thereof, or a fragment thereof, may be used to design nucleic acid probes to identify and clone DNA encoding polypeptides having xylanase activity from strains of different genera or species according to methods well known in the art. In particular, such probes can be used for hybridization with the genomic DNA or cDNA of a cell of interest, following standard Southern blotting procedures, in order to identify and isolate the corresponding gene therein. Such probes can be considerably shorter than the entire sequence, but should be at least 15, e.g., at least 25, at least 35, or at least 70 nucleotides in length. Preferably, the nucleic acid probe is at least 100 nucleotides in length, e.g., at least 200 nucleotides, at least 300 nucleotides, at least 400 nucleotides, at least 500 nucleotides, at least 600 nucleotides, at least 700 nucleotides, at least 800 nucleotides, or at least 900 nucleotides in length. Both DNA and RNA probes can be used. The probes are typically labeled for detecting the corresponding gene (for example, with 32P, 3H, 35S, biotin, or avidin). Such probes are encompassed by the present invention.
A genomic DNA or cDNA library prepared from such other strains may be screened for DNA that hybridizes with the probes described above and encodes a polypeptide having xylanase activity. Genomic or other DNA from such other strains may be separated by agarose or polyacrylamide gel electrophoresis, or other separation techniques. DNA from the libraries or the separated DNA may be transferred to a suitable carrier materials, such as nitrocellulose. In order to identify a clone or DNA that hybridizes with SEQ ID NO: 1 or SEQ ID NO: 5, the mature polypeptide coding sequences thereof, or a subsequence thereof, the carrier material is used in a Southern blot.
For purposes of the present invention, hybridization indicates that the polynucleotide hybridizes to a labeled nucleic acid probe corresponding to (i) SEQ ID NO: 1 or SEQ ID NO: 5; (ii) the mature polypeptide coding sequence of SEQ ID NO: 1 or of SEQ ID NO: 5; (iii) the cDNA sequence of SEQ ID NO: 1 or of SEQ ID NO: 5, or the mature polypeptide coding sequence thereof; (iv) the full-length complement thereof; or (v) a subsequence thereof; under very low to very high stringency conditions. Molecules to which the nucleic acid probe hybridizes under these conditions can be detected using, for example, X-ray film or any other detection means known in the art.
In one aspect, the nucleic acid probe is a polynucleotide that encodes the polypeptide of SEQ ID NO: 2; the mature polypeptide thereof; or a fragment thereof. In another aspect, the nucleic acid probe is SEQ ID NO: 1; the mature polypeptide coding sequence thereof; or the cDNA sequence thereof. In another aspect, the nucleic acid probe is the polynucleotide contained in Rasamsonia byssochiamydoides CBS 413.71, wherein the polynucleotide encodes a polypeptide having xylanase activity. In another aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in Rasamsonia byssochiamydoides CBS 413.71.
In one aspect, the nucleic acid probe is a polynucleotide that encodes the polypeptide of SEQ ID NO: 6; the mature polypeptide thereof; or a fragment thereof. In another aspect, the nucleic acid probe is SEQ ID NO: 5; the mature polypeptide coding sequence thereof; or the cDNA sequence thereof. In another aspect, the nucleic acid probe is the polynucleotide contained in Rasamsonia byssochiamydoides CBS 150.75, wherein the polynucleotide encodes a polypeptide having xylanase activity. In another aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in Rasamsonia byssochiamydoides CBS 150.75.
In another embodiment, the present invention relates to an isolated polypeptide having xylanase activity encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1 or the cDNA sequence thereof of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another embodiment, the present invention relates to an isolated polypeptide having xylanase activity encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 5 or the cDNA sequence thereof of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another embodiment, the present invention relates to variants of the mature polypeptide of SEQ ID NO: 2 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions. In one aspect, the number of amino acid substitutions, deletions and/or insertions introduced into the mature polypeptide of SEQ ID NO: 2 is up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
In another embodiment, the present invention relates to variants of the mature polypeptide of SEQ ID NO: 6 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions. In one aspect, the number of amino acid substitutions, deletions and/or insertions introduced into the mature polypeptide of SEQ ID NO: 6 is up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
The amino acid changes may be of a minor nature, that is conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the protein; small deletions, typically of 1-30 amino acids; small amino- or carboxyl-terminal extensions, such as an amino-terminal methionine residue; a small linker peptide of up to 20-25 residues; or a small extension that facilitates purification by changing net charge or another function, such as a poly-histidine tract, an antigenic epitope or a binding domain.
Examples of conservative substitutions are within the groups of basic amino acids (arginine, lysine and histidine), acidic amino acids (glutamic acid and aspartic acid), polar amino acids (glutamine and asparagine), hydrophobic amino acids (leucine, isoleucine and valine), aromatic amino acids (phenylalanine, tryptophan and tyrosine), and small amino acids (glycine, alanine, serine, threonine and methionine). Amino acid substitutions that do not generally alter specific activity are known in the art and are described, for example, by H. Neurath and R. L. Hill, 1979, In, The Proteins, Academic Press, New York. Common substitutions are Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser, Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Tyr/Phe, Ala/Pro, Lys/Arg, Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu, and Asp/Gly.
Alternatively, the amino acid changes are of such a nature that the physico-chemical properties of the polypeptides are altered. For example, amino acid changes may improve the thermal stability of the polypeptide, alter the substrate specificity, change the pH optimum, and the like.
Essential amino acids in a polypeptide can be identified according to procedures known in the art, such as site-directed mutagenesis or alanine-scanning mutagenesis (Cunningham and Wells, 1989, Science 244: 1081-1085). In the latter technique, single alanine mutations are introduced at every residue in the molecule, and the resultant mutant molecules are tested for xylanase activity to identify amino acid residues that are critical to the activity of the molecule. See also, Hilton et al., 1996, J. Biol. Chem. 271: 4699-4708. The active site of the enzyme or other biological interaction can also be determined by physical analysis of structure, as determined by such techniques as nuclear magnetic resonance, crystallography, electron diffraction, or photoaffinity labeling, in conjunction with mutation of putative contact site amino acids. See, for example, de Vos et al., 1992, Science 255: 306-312; Smith et al., 1992, J. Mol. Biol. 224: 899-904; Wlodaver et al., 1992, FEBS Lett. 309: 59-64. The identity of essential amino acids can also be inferred from an alignment with a related polypeptide.
Single or multiple amino acid substitutions, deletions, and/or insertions can be made and tested using known methods of mutagenesis, recombination, and/or shuffling, followed by a relevant screening procedure, such as those disclosed by Reidhaar-Olson and Sauer, 1988, Science 241: 53-57; Bowie and Sauer, 1989, Proc. Natl. Acad. Sci. USA 86: 2152-2156; WO 95/17413; or WO 95/22625. Other methods that can be used include error-prone PCR, phage display (e.g., Lowman et al., 1991, Biochemistry 30: 10832-10837; U.S. Pat. No. 5,223,409; WO 92/06204), and region-directed mutagenesis (Derbyshire et al., 1986, Gene 46: 145; Ner et al., 1988, DNA 7: 127).
Mutagenesis/shuffling methods can be combined with high-throughput, automated screening methods to detect activity of cloned, mutagenized polypeptides expressed by host cells (Ness et al., 1999, Nature Biotechnology 17: 893-896). Mutagenized DNA molecules that encode active polypeptides can be recovered from the host cells and rapidly sequenced using standard methods in the art. These methods allow the rapid determination of the importance of individual amino acid residues in a polypeptide.
In each of the embodiments above, in one aspect, an isolated polypeptide having xylanase activity of the present invention has at least 10%, e.g., at least 15% and at least 20%, more xylanase activity at pH 4.0 and 60° C. or 65° C. than at pH 4.0 and 50° C. In one aspect, xylanase activity is preferably determined using washed ground-sieved alkaline pretreated corn cobs (GS-APCC) as a substrate according to the protocol described in Example 7 for 72 hours in 50 mM sodium acetate (pH 4.0 to 5.5) or 50 mM Tris (pH 6.0 to 7.0) buffer containing 1 mM manganese sulfate.
In each of the embodiments above, in another aspect, an isolated polypeptide having xylanase activity of the present invention has at least 10%, e.g., at least 15% and at least 20%, more xylanase activity at pH 4.0 and 50° C., 55° C., 60° C., or 65° C. than at pH 6.0 and 50° C., 55° C., 60° C., or 65° C., respectively. In one aspect, xylanase activity is preferably determined using washed ground-sieved alkaline pretreated corn cobs (GS-APCC) as a substrate according to the protocol described in Example 7 for 72 hours in 50 mM sodium acetate (pH 4.0 to 5.5) or 50 mM Tris (pH 6.0 to 7.0) buffer containing 1 mM manganese sulfate.
The polypeptide may be a hybrid polypeptide in which a region of one polypeptide is fused at the N-terminus or the C-terminus of a region of another polypeptide.
The polypeptide may be a fusion polypeptide or cleavable fusion polypeptide in which another polypeptide is fused at the N-terminus or the C-terminus of the polypeptide of the present invention. A fusion polypeptide is produced by fusing a polynucleotide encoding another polypeptide to a polynucleotide of the present invention. Techniques for producing fusion polypeptides are known in the art, and include ligating the coding sequences encoding the polypeptides so that they are in frame and that expression of the fusion polypeptide is under control of the same promoter(s) and terminator. Fusion polypeptides may also be constructed using intein technology in which fusion polypeptides are created post-translationally (Cooper et al., 1993, EMBO J. 12: 2575-2583; Dawson et al., 1994, Science 266: 776-779).
A fusion polypeptide can further comprise a cleavage site between the two polypeptides. Upon secretion of the fusion protein, the site is cleaved releasing the two polypeptides. Examples of cleavage sites include, but are not limited to, the sites disclosed in Martin et al., 2003, J. Ind. Microbiol. Biotechnol. 3: 568-576; Svetina et al., 2000, J. Biotechnol. 76: 245-251; Rasmussen-Wilson et al., 1997, Appl. Environ. Microbiol. 63: 3488-3493; Ward et al., 1995, Biotechnology 13: 498-503; and Contreras et al., 1991, Biotechnology 9: 378-381; Eaton et al., 1986, Biochemistry 25: 505-512; Collins-Racie et al., 1995, Biotechnology 13: 982-987; Carter et al., 1989, Proteins: Structure, Function, and Genetics 6: 240-248; and Stevens, 2003, Drug Discovery World 4: 35-48.
Sources of Polypeptides Having Xylanase Activity
A polypeptide having xylanase activity of the present invention may be obtained from microorganisms of any genus. For purposes of the present invention, the term “obtained from” as used herein in connection with a given source shall mean that the polypeptide encoded by a polynucleotide is produced by the source or by a strain in which the polynucleotide from the source has been inserted. In one aspect, the polypeptide obtained from a given source is secreted extracellularly.
The polypeptide may be a fungal polypeptide. In one aspect, the polypeptide is a Rasamsonia polypeptide. In another aspect, the polypeptide is a Rasamsonia byssochlamydoides polypeptide. In another aspect, the polypeptide is a Rasamsonia byssochlamydoides CBS 413.71 polypeptide. In another aspect, the polypeptide is a Rasamsonia byssochlamydoides CBS 150.75 polypeptide.
It will be understood that for the aforementioned species, the invention encompasses both the perfect and imperfect states, and other taxonomic equivalents, e.g., anamorphs, regardless of the species name by which they are known. Those skilled in the art will readily recognize the identity of appropriate equivalents. For example, the species Rasamsonia byssochlamydoides is sometimes referred to as Talaromyces byssochlamydoides, or by its anamorph Paecilomyces byssochlamydoides. 
Strains of these species are readily accessible to the public in a number of culture collections, such as the American Type Culture Collection (ATCC), Deutsche Sammlung von Mikroorganismen and Zellkulturen GmbH (DSMZ), Centraalbureau Voor Schimmelcultures (CBS), and Agricultural Research Service Patent Culture Collection, Northern Regional Research Center (NRRL).
The polypeptide may be identified and obtained from other sources including microorganisms isolated from nature (e.g., soil, composts, water, etc.) or DNA samples obtained directly from natural materials (e.g., soil, composts, water, etc.) using the above-mentioned probes. Techniques for isolating microorganisms and DNA directly from natural habitats are well known in the art. A polynucleotide encoding the polypeptide may then be obtained by similarly screening a genomic DNA or cDNA library of another microorganism or mixed DNA sample. Once a polynucleotide encoding a polypeptide has been detected with the probe(s), the polynucleotide can be isolated or cloned by utilizing techniques that are known to those of ordinary skill in the art (see, e.g., Sambrook et al., 1989, supra).
Catalytic Domains
In one embodiment, the present invention also relates to catalytic domains having a sequence identity to amino acids 24 to 340 of SEQ ID NO: 2 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. In one aspect, the catalytic domains comprise amino acid sequences that differ by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from amino acids 24 to 340 of SEQ ID NO: 2. The catalytic domain preferably comprises or consists of amino acids 24 to 340 of SEQ ID NO: 2 or an allelic variant thereof; or is a fragment thereof having xylanase activity.
In another embodiment, the present invention also relates to catalytic domains having a sequence identity to amino acids 24 to 341 of SEQ ID NO: 6 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. In one aspect, the catalytic domains comprise amino acid sequences that differ by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from amino acids 24 to 341 of SEQ ID NO: 6. The catalytic domain preferably comprises or consists of amino acids 24 to 341 of SEQ ID NO: 6 or an allelic variant thereof; or is a fragment thereof having xylanase activity.
In another embodiment, the present invention also relates to catalytic domains encoded by polynucleotides having a sequence identity to nucleotides 157 to 1339 of SEQ ID NO: 1 or the cDNA sequence thereof of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. The polynucleotide encoding the catalytic domain preferably comprises or consists of nucleotides 157 to 1339 of SEQ ID NO: 1 or is the sequence contained in Rasamsonia byssochlamydoides strain CBS 413.71.
In another embodiment, the present invention also relates to catalytic domains encoded by polynucleotides having a sequence identity to nucleotides 151 to 1387 of SEQ ID NO: 5 or the cDNA sequence thereof of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. The polynucleotide encoding the catalytic domain preferably comprises or consists of nucleotides 151 to 1387 of SEQ ID NO: 5 or is the sequence contained in Rasamsonia byssochiamydoides strain CBS 150.75.
In another embodiment, the present invention also relates to catalytic domain variants of amino acids 24 to 340 of SEQ ID NO: 2 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions. In one aspect, the number of amino acid substitutions, deletions and/or insertions introduced into the sequence of amino acids 24 to 340 of SEQ ID NO: 2 is up to 10, e.g., 1, 2, 3, 4, 5, 6, 8, 9, or 10.
In another embodiment, the present invention also relates to catalytic domain variants of amino acids 24 to 341 of SEQ ID NO: 6 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions. In one aspect, the number of amino acid substitutions, deletions and/or insertions introduced into the sequence of amino acids 24 to 341 of SEQ ID NO: 6 is up to 10, e.g., 1, 2, 3, 4, 5, 6, 8, 9, or 10.
Carbohydrate Binding Modules
In one embodiment, the present invention also relates to carbohydrate binding modules having a sequence identity to amino acids 373 to 406 of SEQ ID NO: 2 of at least 90%, e.g., at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. In one aspect, the carbohydrate binding modules comprise amino acid sequences that differ by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from amino acids 373 to 406 of SEQ ID NO: 2. The carbohydrate binding module preferably comprises or consists of amino acids 373 to 406 of SEQ ID NO: 2 or an allelic variant thereof; or is a fragment thereof having carbohydrate binding activity.
In one embodiment, the present invention also relates to carbohydrate binding modules having a sequence identity to amino acids 371 to 406 of SEQ ID NO: 6 of at least 90%, e.g., at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. In one aspect, the carbohydrate binding modules comprise amino acid sequences that differ by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from amino acids 371 to 406 of SEQ ID NO: 6. The carbohydrate binding module preferably comprises or consists of amino acids 371 to 406 of SEQ ID NO: 6 or an allelic variant thereof; or is a fragment thereof having carbohydrate binding activity.
In another embodiment, the present invention also relates to carbohydrate binding modules encoded by polynucleotides having a sequence identity to nucleotides 1436 to 1537 of SEQ ID NO: 1 of at least 90%, e.g., at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. The polynucleotide encoding the carbohydrate binding module preferably comprises or consists of nucleotides 1436 to 1537 of SEQ ID NO: 1 or is the sequence contained in Rasamsonia byssochiamydoides CBS 413.71.
In another embodiment, the present invention also relates to carbohydrate binding modules encoded by polynucleotides having a sequence identity to nucleotides 1480 to 1587 of SEQ ID NO: 5 of at least 90%, e.g., at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%. The polynucleotide encoding the carbohydrate binding module preferably comprises or consists of nucleotides 1480 to 1587 of SEQ ID NO: 5 or is the sequence contained in Rasamsonia byssochiamydoides CBS 150.75.
In another embodiment, the present invention also relates to carbohydrate binding module variants of amino acids 373 to 406 of SEQ ID NO: 2 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions. In one aspect, the number of amino acid substitutions, deletions and/or insertions introduced into the sequence of amino acids 373 to 406 of SEQ ID NO: 2 is up to 10, e.g., 1, 2, 3, 4, 5, 6, 8, 9, or 10.
In another embodiment, the present invention also relates to carbohydrate binding module variants of amino acids 371 to 406 of SEQ ID NO: 6 comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions. In one aspect, the number of amino acid substitutions, deletions and/or insertions introduced into the sequence of amino acids 371 to 406 of SEQ ID NO: 6 is up to 10, e.g., 1, 2, 3, 4, 5, 6, 8, 9, or 10.
A catalytic domain operably linked to the carbohydrate binding module may be from a hydrolase, isomerase, ligase, lyase, oxidoreductase, or transferase, e.g., an aminopeptidase, amylase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, alpha-galactosidase, beta-galactosidase, glucoamylase, alpha-glucosidase, beta-glucosidase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, xylanase, or beta-xylosidase. The polynucleotide encoding the catalytic domain may be obtained from any prokaryotic, eukaryotic, or other source.
Polynucleotides
The present invention also relates to isolated polynucleotides encoding a polypeptide, a catalytic domain, or a carbohydrate binding module of the present invention, as described herein.
The techniques used to isolate or clone a polynucleotide are known in the art and include isolation from genomic DNA or cDNA, or a combination thereof. The cloning of the polynucleotides from genomic DNA can be effected, e.g., by using the well known polymerase chain reaction (PCR) or antibody screening of expression libraries to detect cloned DNA fragments with shared structural features. See, e.g., Innis et al., 1990, PCR: A Guide to Methods and Application, Academic Press, New York. Other nucleic acid amplification procedures such as ligase chain reaction (LCR), ligation activated transcription (LAT) and polynucleotide-based amplification (NASBA) may be used. The polynucleotides may be cloned from a strain of Corynascus, or a related organism and thus, for example, may be an allelic or species variant of the polypeptide encoding region of the polynucleotide.
Modification of a polynucleotide encoding a polypeptide of the present invention may be necessary for synthesizing polypeptides substantially similar to the polypeptide. The term “substantially similar” to the polypeptide refers to non-naturally occurring forms of the polypeptide. These polypeptides may differ in some engineered way from the polypeptide isolated from its native source, e.g., variants that differ in specific activity, thermostability, pH optimum, or the like. The variants may be constructed on the basis of the polynucleotide presented as the mature polypeptide coding sequence of SEQ ID NO: 1 or SEQ ID NO: 5, or the cDNA sequence thereof, by introduction of nucleotide substitutions that do not result in a change in the amino acid sequence of the polypeptide, but which correspond to the codon usage of the host organism intended for production of the enzyme, or by introduction of nucleotide substitutions that may give rise to a different amino acid sequence. For a general description of nucleotide substitution, see, e.g., Ford et al., 1991, Protein Expression and Purification 2: 95-107.
Nucleic Acid Constructs
The present invention also relates to nucleic acid constructs comprising a polynucleotide of the present invention operably linked to one or more control sequences that direct the expression of the coding sequence in a suitable host cell under conditions compatible with the control sequences.
The polynucleotide may be manipulated in a variety of ways to provide for expression of the polypeptide. Manipulation of the polynucleotide prior to its insertion into a vector may be desirable or necessary depending on the expression vector. The techniques for modifying polynucleotides utilizing recombinant DNA methods are well known in the art.
The control sequence may be a promoter, a polynucleotide that is recognized by a host cell for expression of a polynucleotide encoding a polypeptide of the present invention. The promoter contains transcriptional control sequences that mediate the expression of the polypeptide. The promoter may be any polynucleotide that shows transcriptional activity in the host cell including mutant, truncated, and hybrid promoters, and may be obtained from genes encoding extracellular or intracellular polypeptides either homologous or heterologous to the host cell.
Examples of suitable promoters for directing transcription of the nucleic acid constructs of the present invention in a bacterial host cell are the promoters obtained from the Bacillus amyloliquefaciens alpha-amylase gene (amyQ), Bacillus licheniformis alpha-amylase gene (amyL), Bacillus licheniformis penicillinase gene (penP), Bacillus stearothermophilus maltogenic amylase gene (amyM), Bacillus subtilis levansucrase gene (sacB), Bacillus subtilis xylA and xylB genes, Bacillus thuringiensis cryllIA gene (Agaisse and Lereclus, 1994, Molecular Microbiology 13: 97-107), E. coli lac operon, E. coli trc promoter (Egon et al., 1988, Gene 69: 301-315), Streptomyces coelicolor agarase gene (dagA), and prokaryotic beta-lactamase gene (Villa-Kamaroff et al., 1978, Proc. Natl. Acad. Sci. USA 75: 3727-3731), as well as the tac promoter (DeBoer et al., 1983, Proc. Natl. Acad. Sci. USA 80: 21-25). Further promoters are described in “Useful proteins from recombinant bacteria” in Gilbert et al., 1980, Scientific American 242: 74-94; and in Sambrook et al., 1989, supra. Examples of tandem promoters are disclosed in WO 99/43835.
Examples of suitable promoters for directing transcription of the nucleic acid constructs of the present invention in a filamentous fungal host cell are promoters obtained from the genes for Aspergillus nidulans acetamidase, Aspergillus niger neutral alpha-amylase, Aspergillus niger acid stable alpha-amylase, Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Aspergillus oryzae TAKA amylase, Aspergillus oryzae alkaline protease, Aspergillus oryzae triose phosphate isomerase, Fusarium oxysporum trypsin-like protease (WO 96/00787), Fusarium venenatum amyloglucosidase (WO 00/56900), Fusarium venenatum Dania (WO 00/56900), Fusarium venenatum Quinn (WO 00/56900), Rhizomucor miehei lipase, Rhizomucor miehei aspartic proteinase, Trichoderma reesei beta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, Trichoderma reesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichoderma reesei endoglucanase III, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei xylanase Ill, Trichoderma reesei beta-xylosidase, and Trichoderma reesei translation elongation factor, as well as the NA2-tpi promoter (a modified promoter from an Aspergillus neutral alpha-amylase gene in which the untranslated leader has been replaced by an untranslated leader from an Aspergillus triose phosphate isomerase gene; non-limiting examples include modified promoters from an Aspergillus niger neutral alpha-amylase gene in which the untranslated leader has been replaced by an untranslated leader from an Aspergillus nidulans or Aspergillus oryzae triose phosphate isomerase gene); and mutant, truncated, and hybrid promoters thereof. Other promoters are described in U.S. Pat. No. 6,011,147.
In a yeast host, useful promoters are obtained from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae galactokinase (GAL1), Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH1, ADH2/GAP), Saccharomyces cerevisiae triose phosphate isomerase (TPI), Saccharomyces cerevisiae metallothionein (CUP1), and Saccharomyces cerevisiae 3-phosphoglycerate kinase. Other useful promoters for yeast host cells are described by Romanos et al., 1992, Yeast 8: 423-488.
The control sequence may also be a transcription terminator, which is recognized by a host cell to terminate transcription. The terminator is operably linked to the 3′-terminus of the polynucleotide encoding the polypeptide. Any terminator that is functional in the host cell may be used in the present invention.
Preferred terminators for bacterial host cells are obtained from the genes for Bacillus clausii alkaline protease (aprH), Bacillus licheniformis alpha-amylase (amyL), and Escherichia coli ribosomal RNA (rrnB).
Preferred terminators for filamentous fungal host cells are obtained from the genes for Aspergillus nidulans acetamidase, Aspergillus nidulans anthranilate synthase, Aspergillus niger glucoamylase, Aspergillus niger alpha-glucosidase, Aspergillus oryzae TAKA amylase, Fusarium oxysporum trypsin-like protease, Trichoderma reesei beta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, Trichoderma reesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichoderma reesei endoglucanase III, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei xylanase III, Trichoderma reesei beta-xylosidase, and Trichoderma reesei translation elongation factor.
Preferred terminators for yeast host cells are obtained from the genes for Saccharomyces cerevisiae enolase, Saccharomyces cerevisiae cytochrome C (CYC1), and Saccharomyces cerevisiae glyceraldehyde-3-phosphate dehydrogenase. Other useful terminators for yeast host cells are described by Romanos et al., 1992, supra.
The control sequence may also be an mRNA stabilizer region downstream of a promoter and upstream of the coding sequence of a gene which increases expression of the gene.
Examples of suitable mRNA stabilizer regions are obtained from a Bacillus thuringiensis cryllIA gene (WO 94/25612) and a Bacillus subtilis SP82 gene (Hue et al., 1995, Journal of Bacteriology 177: 3465-3471).
The control sequence may also be a leader, a nontranslated region of an mRNA that is important for translation by the host cell. The leader is operably linked to the 5′-terminus of the polynucleotide encoding the polypeptide. Any leader that is functional in the host cell may be used.
Preferred leaders for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase and Aspergillus nidulans triose phosphate isomerase.
Suitable leaders for yeast host cells are obtained from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae 3-phosphoglycerate kinase, Saccharomyces cerevisiae alpha-factor, and Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP).
The control sequence may also be a polyadenylation sequence, a sequence operably linked to the 3′-terminus of the polynucleotide and, when transcribed, is recognized by the host cell as a signal to add polyadenosine residues to transcribed mRNA. Any polyadenylation sequence that is functional in the host cell may be used.
Preferred polyadenylation sequences for filamentous fungal host cells are obtained from the genes for Aspergillus nidulans anthranilate synthase, Aspergillus niger glucoamylase, Aspergillus niger alpha-glucosidase Aspergillus oryzae TAKA amylase, and Fusarium oxysporum trypsin-like protease.
Useful polyadenylation sequences for yeast host cells are described by Guo and Sherman, 1995, Mol. Cellular Biol. 15: 5983-5990.
The control sequence may also be a signal peptide coding region that encodes a signal peptide linked to the N-terminus of a polypeptide and directs the polypeptide into the cell's secretory pathway. The 5′-end of the coding sequence of the polynucleotide may inherently contain a signal peptide coding sequence naturally linked in translation reading frame with the segment of the coding sequence that encodes the polypeptide. Alternatively, the 5′-end of the coding sequence may contain a signal peptide coding sequence that is foreign to the coding sequence. A foreign signal peptide coding sequence may be required where the coding sequence does not naturally contain a signal peptide coding sequence. Alternatively, a foreign signal peptide coding sequence may simply replace the natural signal peptide coding sequence in order to enhance secretion of the polypeptide. However, any signal peptide coding sequence that directs the expressed polypeptide into the secretory pathway of a host cell may be used.
Effective signal peptide coding sequences for bacterial host cells are the signal peptide coding sequences obtained from the genes for Bacillus NCIB 11837 maltogenic amylase, Bacillus licheniformis subtilisin, Bacillus licheniformis beta-lactamase, Bacillus stearothermophilus alpha-amylase, Bacillus stearothermophilus neutral proteases (nprT, nprS, nprM), and Bacillus subtilis prsA. Further signal peptides are described by Simonen and Palva, 1993, Microbiological Reviews 57: 109-137.
Effective signal peptide coding sequences for filamentous fungal host cells are the signal peptide coding sequences obtained from the genes for Aspergillus niger neutral amylase, Aspergillus niger glucoamylase, Aspergillus oryzae TAKA amylase, Humicola insolens cellulase, Humicola insolens endoglucanase V, Humicola lanuginosa lipase, and Rhizomucor miehei aspartic proteinase.
Useful signal peptides for yeast host cells are obtained from the genes for Saccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiae invertase. Other useful signal peptide coding sequences are described by Romanos et al., 1992, supra.
The control sequence may also be a propeptide coding sequence that encodes a propeptide positioned at the N-terminus of a polypeptide. The resultant polypeptide is known as a proenzyme or propolypeptide (or a zymogen in some cases). A propolypeptide is generally inactive and can be converted to an active polypeptide by catalytic or autocatalytic cleavage of the propeptide from the propolypeptide. The propeptide coding sequence may be obtained from the genes for Bacillus subtilis alkaline protease (aprE), Bacillus subtilis neutral protease (nprT), Myceliophthora thermophila laccase (WO 95/33836), Rhizomucor miehei aspartic proteinase, and Saccharomyces cerevisiae alpha-factor.
Where both signal peptide and propeptide sequences are present, the propeptide sequence is positioned next to the N-terminus of a polypeptide and the signal peptide sequence is positioned next to the N-terminus of the propeptide sequence.
It may also be desirable to add regulatory sequences that regulate expression of the polypeptide relative to the growth of the host cell. Examples of regulatory sequences are those that cause expression of the gene to be turned on or off in response to a chemical or physical stimulus, including the presence of a regulatory compound. Regulatory sequences in prokaryotic systems include the lac, tac, and trp operator systems. In yeast, the ADH2 system or GAL1 system may be used. In filamentous fungi, the Aspergillus niger glucoamylase promoter, Aspergillus oryzae TAKA alpha-amylase promoter, and Aspergillus oryzae glucoamylase promoter, Trichoderma reesei cellobiohydrolase I promoter, and Trichoderma reesei cellobiohydrolase II promoter may be used. Other examples of regulatory sequences are those that allow for gene amplification. In eukaryotic systems, these regulatory sequences include the dihydrofolate reductase gene that is amplified in the presence of methotrexate, and the metallothionein genes that are amplified with heavy metals. In these cases, the polynucleotide encoding the polypeptide would be operably linked to the regulatory sequence.
Expression Vectors
The present invention also relates to recombinant expression vectors comprising a polynucleotide of the present invention, a promoter, and transcriptional and translational stop signals. The various nucleotide and control sequences may be joined together to produce a recombinant expression vector that may include one or more convenient restriction sites to allow for insertion or substitution of the polynucleotide encoding the polypeptide at such sites. Alternatively, the polynucleotide may be expressed by inserting the polynucleotide or a nucleic acid construct comprising the polynucleotide into an appropriate vector for expression. In creating the expression vector, the coding sequence is located in the vector so that the coding sequence is operably linked with the appropriate control sequences for expression.
The recombinant expression vector may be any vector (e.g., a plasmid or virus) that can be conveniently subjected to recombinant DNA procedures and can bring about expression of the polynucleotide. The choice of the vector will typically depend on the compatibility of the vector with the host cell into which the vector is to be introduced. The vector may be a linear or closed circular plasmid.
The vector may be an autonomously replicating vector, i.e., a vector that exists as an extrachromosomal entity, the replication of which is independent of chromosomal replication, e.g., a plasmid, an extrachromosomal element, a minichromosome, or an artificial chromosome. The vector may contain any means for assuring self-replication. Alternatively, the vector may be one that, when introduced into the host cell, is integrated into the genome and replicated together with the chromosome(s) into which it has been integrated. Furthermore, a single vector or plasmid or two or more vectors or plasmids that together contain the total DNA to be introduced into the genome of the host cell, or a transposon, may be used.
The vector preferably contains one or more selectable markers that permit easy selection of transformed, transfected, transduced, or the like cells. A selectable marker is a gene the product of which provides for biocide or viral resistance, resistance to heavy metals, prototrophy to auxotrophs, and the like.
Examples of bacterial selectable markers are Bacillus licheniformis or Bacillus subtilis dal genes, or markers that confer antibiotic resistance such as ampicillin, chloramphenicol, kanamycin, neomycin, spectinomycin, or tetracycline resistance. Suitable markers for yeast host cells include, but are not limited to, ADE2, HIS3, LEU2, LYS2, MET3, TRP1, and URA3. Selectable markers for use in a filamentous fungal host cell include, but are not limited to, adeA (phosphoribosylaminoim idazole-succinocarboxam ide synthase), adeB (phosphoribosyl-aminoimidazole synthase), amdS (acetamidase), argB (ornithine carbamoyltransferase), bar (phosphinothricin acetyltransferase), hph (hygromycin phosphotransferase), niaD (nitrate reductase), pyrG (orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase), and trpC (anthranilate synthase), as well as equivalents thereof. Preferred for use in an Aspergillus cell are Aspergillus nidulans or Aspergillus oryzae amdS and pyrG genes and a Streptomyces hygroscopicus bar gene. Preferred for use in a Trichoderma cell are adeA, adeB, amdS, hph, and pyrG genes.
The selectable marker may be a dual selectable marker system as described in WO 2010/039889. In one aspect, the dual selectable marker is a hph-tk dual selectable marker system.
The vector preferably contains an element(s) that permits integration of the vector into the host cell's genome or autonomous replication of the vector in the cell independent of the genome.
For integration into the host cell genome, the vector may rely on the polynucleotide's sequence encoding the polypeptide or any other element of the vector for integration into the genome by homologous or non-homologous recombination. Alternatively, the vector may contain additional polynucleotides for directing integration by homologous recombination into the genome of the host cell at a precise location(s) in the chromosome(s). To increase the likelihood of integration at a precise location, the integrational elements should contain a sufficient number of nucleic acids, such as 100 to 10,000 base pairs, 400 to 10,000 base pairs, and 800 to 10,000 base pairs, which have a high degree of sequence identity to the corresponding target sequence to enhance the probability of homologous recombination. The integrational elements may be any sequence that is homologous with the target sequence in the genome of the host cell. Furthermore, the integrational elements may be non-encoding or encoding polynucleotides. On the other hand, the vector may be integrated into the genome of the host cell by non-homologous recombination.
For autonomous replication, the vector may further comprise an origin of replication enabling the vector to replicate autonomously in the host cell in question. The origin of replication may be any plasmid replicator mediating autonomous replication that functions in a cell. The term “origin of replication” or “plasmid replicator” means a polynucleotide that enables a plasmid or vector to replicate in vivo.
Examples of bacterial origins of replication are the origins of replication of plasmids pBR322, pUC19, pACYC177, and pACYC184 permitting replication in E. coli, and pUB110, pE194, pTA1060, and pAMβ1 permitting replication in Bacillus. 
Examples of origins of replication for use in a yeast host cell are the 2 micron origin of replication, ARS1, ARS4, the combination of ARS1 and CEN3, and the combination of ARS4 and CEN6.
Examples of origins of replication useful in a filamentous fungal cell are AMA1 and ANSI (Gems et al., 1991, Gene 98: 61-67; Cullen et al., 1987, Nucleic Acids Res. 15: 9163-9175; WO 00/24883). Isolation of the AMA1 gene and construction of plasmids or vectors comprising the gene can be accomplished according to the methods disclosed in WO 00/24883.
More than one copy of a polynucleotide of the present invention may be inserted into a host cell to increase production of a polypeptide. An increase in the copy number of the polynucleotide can be obtained by integrating at least one additional copy of the sequence into the host cell genome or by including an amplifiable selectable marker gene with the polynucleotide where cells containing amplified copies of the selectable marker gene, and thereby additional copies of the polynucleotide, can be selected for by cultivating the cells in the presence of the appropriate selectable agent.
The procedures used to ligate the elements described above to construct the recombinant expression vectors of the present invention are well known to one skilled in the art (see, e.g., Sambrook et al., 1989, supra).
Host Cells
The present invention also relates to recombinant host cells, comprising a polynucleotide of the present invention operably linked to one or more control sequences that direct the production of a polypeptide of the present invention. A construct or vector comprising a polynucleotide is introduced into a host cell so that the construct or vector is maintained as a chromosomal integrant or as a self-replicating extra-chromosomal vector as described earlier. The term “host cell” encompasses any progeny of a parent cell that is not identical to the parent cell due to mutations that occur during replication. The choice of a host cell will to a large extent depend upon the gene encoding the polypeptide and its source.
The host cell may be any cell useful in the recombinant production of a polypeptide of the present invention, e.g., a prokaryote or a eukaryote.
The prokaryotic host cell may be any Gram-positive or Gram-negative bacterium. Gram-positive bacteria include, but are not limited to, Bacillus, Clostridium, Enterococcus, Geobacillus, Lactobacillus, Lactococcus, Oceanobacillus, Staphylococcus, Streptococcus, and Streptomyces. Gram-negative bacteria include, but are not limited to, Campylobacter, E. coli, Flavobacterium, Fusobacterium, Helicobacter, Ilyobacter, Neisseria, Pseudomonas, Salmonella, and Ureaplasma. 
The bacterial host cell may be any Bacillus cell including, but not limited to, Bacillus alkalophilus, Bacillus amyloliquefaciens, Bacillus brevis, Bacillus circulans, Bacillus clausii, Bacillus coagulans, Bacillus firmus, Bacillus lautus, Bacillus lentus, Bacillus licheniformis, Bacillus megaterium, Bacillus pumilus, Bacillus stearothermophilus, Bacillus subtilis, and Bacillus thuringiensis cells.
The introduction of DNA into a Bacillus cell may be effected by protoplast transformation (see, e.g., Chang and Cohen, 1979, Mol. Gen. Genet. 168: 111-115), competent cell transformation (see, e.g., Young and Spizizen, 1961, J. Bacteriol. 81: 823-829, or Dubnau and Davidoff-Abelson, 1971, J. Mol. Biol. 56: 209-221), electroporation (see, e.g., Shigekawa and Dower, 1988, Biotechniques 6: 742-751), or conjugation (see, e.g., Koehler and Thorne, 1987, J. Bacteriol. 169: 5271-5278). The introduction of DNA into an E. coli cell may be effected by protoplast transformation (see, e.g., Hanahan, 1983, J. Mol. Biol. 166: 557-580) or electroporation (see, e.g., Dower et al., 1988, Nucleic Acids Res. 16: 6127-6145). The introduction of DNA into a Streptomyces cell may be effected by protoplast transformation, electroporation (see, e.g., Gong et al., 2004, Folia Microbiol. (Praha) 49: 399-405), conjugation (see, e.g., Mazodier et al., 1989, J. Bacteriol. 171: 3583-3585), or transduction (see, e.g., Burke et al., 2001, Proc. Natl. Acad. Sci. USA 98: 6289-6294). The introduction of DNA into a Pseudomonas cell may be effected by electroporation (see, e.g., Choi et al., 2006, J. Microbiol. Methods 64: 391-397) or conjugation (see, e.g., Pinedo and Smets, 2005, Appl. Environ. Microbiol. 71: 51-57). The introduction of DNA into a Streptococcus cell may be effected by natural competence (see, e.g., Perry and Kuramitsu, 1981, Infect. Immun. 32: 1295-1297), protoplast transformation (see, e.g., Catt and Jollick, 1991, Microbios 68: 189-207), electroporation (see, e.g., Buckley et al., 1999, Appl. Environ. Microbiol. 65: 3800-3804), or conjugation (see, e.g., Clewell, 1981, Microbiol. Rev. 45: 409-436). However, any method known in the art for introducing DNA into a host cell can be used.
The host cell may also be a eukaryote, such as a mammalian, insect, plant, or fungal cell.
The host cell may be a fungal cell. “Fungi” as used herein includes the phyla Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota as well as the Oomycota and all mitosporic fungi (as defined by Hawksworth et al., In, Ainsworth and Bisby's Dictionary of The Fungi, 8th edition, 1995, CAB International, University Press, Cambridge, UK).
The fungal host cell may be a yeast cell. “Yeast” as used herein includes ascosporogenous yeast (Endomycetales), basidiosporogenous yeast, and yeast belonging to the Fungi Imperfecti (Blastomycetes). Since the classification of yeast may change in the future, for the purposes of this invention, yeast shall be defined as described in Biology and Activities of Yeast (Skinner, Passmore, and Davenport, editors, Soc. App. Bacteriol. Symposium Series No. 9, 1980).
The yeast host cell may be a Candida, Hansenula, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, or Yarrowia cell, such as a Kluyveromyces lactis, Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis, Saccharomyces oviformis, or Yarrowia lipolytica cell.
The fungal host cell may be a filamentous fungal cell. “Filamentous fungi” include all filamentous forms of the subdivision Eumycota and Oomycota (as defined by Hawksworth et al., 1995, supra). The filamentous fungi are generally characterized by a mycelial wall composed of chitin, cellulose, glucan, chitosan, mannan, and other complex polysaccharides. Vegetative growth is by hyphal elongation and carbon catabolism is obligately aerobic. In contrast, vegetative growth by yeasts such as Saccharomyces cerevisiae is by budding of a unicellular thallus and carbon catabolism may be fermentative.
The filamentous fungal host cell may be an Acremonium, Aspergillus, Aureobasidium, Bjerkandera, Ceriporiopsis, Chrysosporium, Coprinus, Coriolus, Cryptococcus, Filibasidium, Fusarium, Humicola, Magnaporthe, Mucor, Myceliophthora, Neocallimastix, Neurospora, Paecilomyces, Penicillium, Phanerochaete, Phiebia, Piromyces, Pleurotus, Schizophyllum, Talaromyces, Thermoascus, Thielavia, Tolypocladium, Trametes, or Trichoderma cell.
For example, the filamentous fungal host cell may be an Aspergillus awamori, Aspergillus foetidus, Aspergillus fumigatus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Bjerkandera adusta, Ceriporiopsis aneirina, Ceriporiopsis caregiea, Ceriporiopsis gilvescens, Ceriporiopsis pannocinta, Ceriporiopsis rivulosa, Ceriporiopsis subrufa, Ceriporiopsis subvermispora, Chrysosporium inops, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium merdarium, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium tropicum, Chrysosporium zonatum, Coprinus cinereus, Coriolus hirsutus, Fusarium bactridioides, Fusarium cerealis, Fusarium crookwellense, Fusarium culmorum, Fusarium graminearum, Fusarium graminum, Fusarium heterosporum, Fusarium negundi, Fusarium oxysporum, Fusarium reticulatum, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum, Fusarium sporotrichioides, Fusarium sulphureum, Fusarium torulosum, Fusarium trichothecioides, Fusarium venenatum, Humicola insolens, Humicola lanuginosa, Mucor miehei, Myceliophthora thermophila, Neurospora crassa, Penicillium purpurogenum, Phanerochaete chrysosporium, Phiebia radiata, Pleurotus eryngii, Thielavia terrestris, Trametes villosa, Trametes versicolor, Trichoderma harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, or Trichoderma viride cell.
Fungal cells may be transformed by a process involving protoplast formation, transformation of the protoplasts, and regeneration of the cell wall in a manner known per se. Suitable procedures for transformation of Aspergillus and Trichoderma host cells are described in EP 238023, Yelton et al., 1984, Proc. Natl. Acad. Sci. USA 81: 1470-1474, and Christensen et al., 1988, Bio/Technology 6: 1419-1422. Suitable methods for transforming Fusarium species are described by Malardier et al., 1989, Gene 78: 147-156, and WO 96/00787. Yeast may be transformed using the procedures described by Becker and Guarente, In Abelson, J. N. and Simon, M. I., editors, Guide to Yeast Genetics and Molecular Biology, Methods in Enzymology, Volume 194, pp 182-187, Academic Press, Inc., New York; Ito et al., 1983, J. Bacteriol. 153: 163; and Hinnen et al., 1978, Proc. Natl. Acad. Sci. USA 75: 1920.
Methods of Production
The present invention also relates to methods of producing a polypeptide of the present invention, comprising (a) cultivating a cell, which in its wild-type form produces the polypeptide, under conditions conducive for production of the polypeptide; and optionally (b) recovering the polypeptide. In one aspect, the cell is a Rasamsonia cell. In another aspect, the cell is a Rasamsonia byssochlamydoides cell. In another aspect, the cell is a Rasamsonia byssochiamydoides CBS 413.71 cell. In another aspect, the cell is a Rasamsonia byssochiamydoides CBS 150.75 cell.
The present invention also relates to methods of producing a polypeptide of the present invention, comprising (a) cultivating a recombinant host cell of the present invention under conditions conducive for production of the polypeptide; and optionally (b) recovering the polypeptide.
The host cells are cultivated in a nutrient medium suitable for production of the polypeptide using methods known in the art. For example, the cells may be cultivated by shake flask cultivation, or small-scale or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermentors in a suitable medium and under conditions allowing the polypeptide to be expressed and/or isolated. The cultivation takes place in a suitable nutrient medium comprising carbon and nitrogen sources and inorganic salts, using procedures known in the art. Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). If the polypeptide is secreted into the nutrient medium, the polypeptide can be recovered directly from the medium. If the polypeptide is not secreted, it can be recovered from cell lysates.
The polypeptide may be detected using methods known in the art that are specific for the polypeptides. These detection methods include, but are not limited to, use of specific antibodies, formation of an enzyme product, or disappearance of an enzyme substrate. For example, an enzyme assay may be used to determine the activity of the polypeptide.
The polypeptide may be recovered using methods known in the art. For example, the polypeptide may be recovered from the nutrient medium by conventional procedures including, but not limited to, collection, centrifugation, filtration, extraction, spray-drying, evaporation, or precipitation. In one aspect, a whole fermentation broth comprising a polypeptide having xylanase activity of the present invention is recovered.
The polypeptide may be purified by a variety of procedures known in the art including, but not limited to, chromatography (e.g., ion exchange, affinity, hydrophobic, chromatofocusing, and size exclusion), electrophoretic procedures (e.g., preparative isoelectric focusing), differential solubility (e.g., ammonium sulfate precipitation), SDS-PAGE, or extraction (see, e.g., Protein Purification, Janson and Ryden, editors, VCH Publishers, New York, 1989) to obtain substantially pure polypeptides.
Plants
The present invention also relates to isolated plants, e.g., a transgenic plant, plant part, or plant cell, comprising a polynucleotide to express and produce a polypeptide or domain of the present invention in recoverable quantities. The polypeptide or domain may be recovered from the plant or plant part. Alternatively, the plant or plant part containing the polypeptide or domain may be used as such for improving the quality of a food or feed, e.g., improving nutritional value, palatability, and rheological properties, or to destroy an antinutritive factor.
The transgenic plant can be dicotyledonous (a dicot) or monocotyledonous (a monocot). Examples of monocot plants are grasses, such as meadow grass (blue grass, Poa), forage grass such as Festuca, Lolium, temperate grass, such as Agrostis, and cereals, e.g., wheat, oats, rye, barley, rice, sorghum, and maize (corn).
Examples of dicot plants are tobacco, legumes, such as lupins, potato, sugar beet, pea, bean and soybean, and cruciferous plants (family Brassicaceae), such as cauliflower, rape seed, and the closely related model organism Arabidopsis thaliana. 
Examples of plant parts are stem, callus, leaves, root, fruits, seeds, and tubers as well as the individual tissues comprising these parts, e.g., epidermis, mesophyll, parenchyme, vascular tissues, meristems. Specific plant cell compartments, such as chloroplasts, apoplasts, mitochondria, vacuoles, peroxisomes and cytoplasm are also considered to be a plant part. Furthermore, any plant cell, whatever the tissue origin, is considered to be a plant part. Likewise, plant parts such as specific tissues and cells isolated to facilitate the utilization of the invention are also considered plant parts, e.g., embryos, endosperms, aleurone and seed coats.
Also included within the scope of the present invention are the progeny of such plants, plant parts, and plant cells.
The transgenic plant or plant cell expressing the polypeptide or domain may be constructed in accordance with methods known in the art. In short, the plant or plant cell is constructed by incorporating one or more expression constructs encoding the polypeptide or domain into the plant host genome or chloroplast genome and propagating the resulting modified plant or plant cell into a transgenic plant or plant cell.
The expression construct is conveniently a nucleic acid construct that comprises a polynucleotide encoding a polypeptide or domain operably linked with appropriate regulatory sequences required for expression of the polynucleotide in the plant or plant part of choice. Furthermore, the expression construct may comprise a selectable marker useful for identifying plant cells into which the expression construct has been integrated and DNA sequences necessary for introduction of the construct into the plant in question (the latter depends on the DNA introduction method to be used).
The choice of regulatory sequences, such as promoter and terminator sequences and optionally signal or transit sequences, is determined, for example, on the basis of when, where, and how the polypeptide or domain is desired to be expressed (Sticklen, 2008, Nature Rev. 9: 433-443). For instance, the expression of the gene encoding a polypeptide or domain may be constitutive or inducible, or may be developmental, stage or tissue specific, and the gene product may be targeted to a specific tissue or plant part such as seeds or leaves. Regulatory sequences are, for example, described by Tague et al., 1988, Plant Physiology 86: 506.
For constitutive expression, the 35S-CaMV, the maize ubiquitin 1, or the rice actin 1 promoter may be used (Franck et al., 1980, Cell 21: 285-294; Christensen et al., 1992, Plant Mol. Biol. 18: 675-689; Zhang et al., 1991, Plant Cell 3: 1155-1165). Organ-specific promoters may be, for example, a promoter from storage sink tissues such as seeds, potato tubers, and fruits (Edwards and Coruzzi, 1990, Ann. Rev. Genet. 24: 275-303), or from metabolic sink tissues such as meristems (Ito et al., 1994, Plant Mol. Biol. 24: 863-878), a seed specific promoter such as the glutelin, prolamin, globulin, or albumin promoter from rice (Wu et al., 1998, Plant Cell Physiol. 39: 885-889), a Vicia faba promoter from the legumin B4 and the unknown seed protein gene from Vicia faba (Conrad et al., 1998, J. Plant Physiol. 152: 708-711), a promoter from a seed oil body protein (Chen et al., 1998, Plant Cell Physiol. 39: 935-941), the storage protein napA promoter from Brassica napus, or any other seed specific promoter known in the art, e.g., as described in WO 91/14772. Furthermore, the promoter may be a leaf specific promoter such as the rbcs promoter from rice or tomato (Kyozuka et al., 1993, Plant Physiol. 102: 991-1000), the chlorella virus adenine methyltransferase gene promoter (Mitra and Higgins, 1994, Plant Mol. Biol. 26: 85-93), the aldP gene promoter from rice (Kagaya et al., 1995, Mol. Gen. Genet. 248: 668-674), or a wound inducible promoter such as the potato pin2 promoter (Xu et al., 1993, Plant Mol. Biol. 22: 573-588). Likewise, the promoter may be induced by abiotic treatments such as temperature, drought, or alterations in salinity or induced by exogenously applied substances that activate the promoter, e.g., ethanol, oestrogens, plant hormones such as ethylene, abscisic acid, and gibberellic acid, and heavy metals.
A promoter enhancer element may also be used to achieve higher expression of a polypeptide or domain in the plant. For instance, the promoter enhancer element may be an intron that is placed between the promoter and the polynucleotide encoding a polypeptide or domain. For instance, Xu et al., 1993, supra, disclose the use of the first intron of the rice actin 1 gene to enhance expression.
The selectable marker gene and any other parts of the expression construct may be chosen from those available in the art.
The nucleic acid construct is incorporated into the plant genome according to conventional techniques known in the art, including Agrobacterium-mediated transformation, virus-mediated transformation, microinjection, particle bombardment, biolistic transformation, and electroporation (Gasser et al., 1990, Science 244: 1293; Potrykus, 1990, Bio/Technology 8: 535; Shimamoto et al., 1989, Nature 338: 274).
Agrobacterium tumefaciens-mediated gene transfer is a method for generating transgenic dicots (for a review, see Hooykas and Schilperoort, 1992, Plant Mol. Biol. 19: 15-38) and for transforming monocots, although other transformation methods may be used for these plants. A method for generating transgenic monocots is particle bombardment (microscopic gold or tungsten particles coated with the transforming DNA) of embryonic calli or developing embryos (Christou, 1992, Plant J. 2: 275-281; Shimamoto, 1994, Curr. Opin. Biotechnol. 5: 158-162; Vasil et al., 1992, Bio/Technology 10: 667-674). An alternative method for transformation of monocots is based on protoplast transformation as described by Omirulleh et al., 1993, Plant Mol. Biol. 21: 415-428. Additional transformation methods include those described in U.S. Pat. Nos. 6,395,966 and 7,151,204 (both of which are herein incorporated by reference in their entirety).
Following transformation, the transformants having incorporated the expression construct are selected and regenerated into whole plants according to methods well known in the art. Often the transformation procedure is designed for the selective elimination of selection genes either during regeneration or in the following generations by using, for example, co-transformation with two separate T-DNA constructs or site specific excision of the selection gene by a specific recombinase.
In addition to direct transformation of a particular plant genotype with a construct of the present invention, transgenic plants may be made by crossing a plant having the construct to a second plant lacking the construct. For example, a construct encoding a polypeptide or domain can be introduced into a particular plant variety by crossing, without the need for ever directly transforming a plant of that given variety. Therefore, the present invention encompasses not only a plant directly regenerated from cells which have been transformed in accordance with the present invention, but also the progeny of such plants. As used herein, progeny may refer to the offspring of any generation of a parent plant prepared in accordance with the present invention. Such progeny may include a DNA construct prepared in accordance with the present invention. Crossing results in the introduction of a transgene into a plant line by cross pollinating a starting line with a donor plant line. Non-limiting examples of such steps are described in U.S. Pat. No. 7,151,204.
Plants may be generated through a process of backcross conversion. For example, plants include plants referred to as a backcross converted genotype, line, inbred, or hybrid.
Genetic markers may be used to assist in the introgression of one or more transgenes of the invention from one genetic background into another. Marker assisted selection offers advantages relative to conventional breeding in that it can be used to avoid errors caused by phenotypic variations. Further, genetic markers may provide data regarding the relative degree of elite germplasm in the individual progeny of a particular cross. For example, when a plant with a desired trait which otherwise has a non-agronomically desirable genetic background is crossed to an elite parent, genetic markers may be used to select progeny which not only possess the trait of interest, but also have a relatively large proportion of the desired germplasm. In this way, the number of generations required to introgress one or more traits into a particular genetic background is minimized.
The present invention also relates to methods of producing a polypeptide or domain of the present invention comprising (a) cultivating a transgenic plant or a plant cell comprising a polynucleotide encoding the polypeptide or domain under conditions conducive for production of the polypeptide or domain; and (b) recovering the polypeptide or domain.
Removal or Reduction of Xylanase Activity
The present invention also relates to methods of producing a mutant of a parent cell, which comprises disrupting or deleting a polynucleotide, or a portion thereof, encoding a polypeptide of the present invention, which results in the mutant cell producing less of the polypeptide than the parent cell when cultivated under the same conditions.
The mutant cell may be constructed by reducing or eliminating expression of the polynucleotide using methods well known in the art, for example, insertions, disruptions, replacements, or deletions. In a preferred aspect, the polynucleotide is inactivated. The polynucleotide to be modified or inactivated may be, for example, the coding region or a part thereof essential for activity, or a regulatory element required for expression of the coding region. An example of such a regulatory or control sequence may be a promoter sequence or a functional part thereof, i.e., a part that is sufficient for affecting expression of the polynucleotide. Other control sequences for possible modification include, but are not limited to, a leader, polyadenylation sequence, propeptide sequence, signal peptide sequence, transcription terminator, and transcriptional activator.
Modification or inactivation of the polynucleotide may be performed by subjecting the parent cell to mutagenesis and selecting for mutant cells in which expression of the polynucleotide has been reduced or eliminated. The mutagenesis, which may be specific or random, may be performed, for example, by use of a suitable physical or chemical mutagenizing agent, by use of a suitable oligonucleotide, or by subjecting the DNA sequence to PCR generated mutagenesis. Furthermore, the mutagenesis may be performed by use of any combination of these mutagenizing agents.
Examples of a physical or chemical mutagenizing agent suitable for the present purpose include ultraviolet (UV) irradiation, hydroxylamine, N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), O-methyl hydroxylamine, nitrous acid, ethyl methane sulphonate (EMS), sodium bisulphite, formic acid, and nucleotide analogues.
When such agents are used, the mutagenesis is typically performed by incubating the parent cell to be mutagenized in the presence of the mutagenizing agent of choice under suitable conditions, and screening and/or selecting for mutant cells exhibiting reduced or no expression of the gene.
Modification or inactivation of the polynucleotide may be accomplished by insertion, substitution, or deletion of one or more nucleotides in the gene or a regulatory element required for transcription or translation thereof. For example, nucleotides may be inserted or removed so as to result in the introduction of a stop codon, the removal of the start codon, or a change in the open reading frame. Such modification or inactivation may be accomplished by site-directed mutagenesis or PCR generated mutagenesis in accordance with methods known in the art. Although, in principle, the modification may be performed in vivo, i.e., directly on the cell expressing the polynucleotide to be modified, it is preferred that the modification be performed in vitro as exemplified below.
An example of a convenient way to eliminate or reduce expression of a polynucleotide is based on techniques of gene replacement, gene deletion, or gene disruption. For example, in the gene disruption method, a nucleic acid sequence corresponding to the endogenous polynucleotide is mutagenized in vitro to produce a defective nucleic acid sequence that is then transformed into the parent cell to produce a defective gene. By homologous recombination, the defective nucleic acid sequence replaces the endogenous polynucleotide. It may be desirable that the defective polynucleotide also encodes a marker that may be used for selection of transformants in which the polynucleotide has been modified or destroyed. In an aspect, the polynucleotide is disrupted with a selectable marker such as those described herein.
The present invention also relates to methods of inhibiting the expression of a polypeptide having xylanase activity in a cell, comprising administering to the cell or expressing in the cell a double-stranded RNA (dsRNA) molecule, wherein the dsRNA comprises a subsequence of a polynucleotide of the present invention. In a preferred aspect, the dsRNA is about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more duplex nucleotides in length. The dsRNA is preferably a small interfering RNA (siRNA) or a micro RNA (miRNA). In a preferred aspect, the dsRNA is small interfering RNA for inhibiting transcription. In another preferred aspect, the dsRNA is micro RNA for inhibiting translation.
The present invention also relates to such double-stranded RNA (dsRNA) molecules, comprising a portion of the mature polypeptide coding sequence of SEQ ID NO: 1 or of SEQ ID NO: 5 for inhibiting expression of the polypeptide in a cell. While the present invention is not limited by any particular mechanism of action, the dsRNA can enter a cell and cause the degradation of a single-stranded RNA (ssRNA) of similar or identical sequences, including endogenous mRNAs. When a cell is exposed to dsRNA, mRNA from the homologous gene is selectively degraded by a process called RNA interference (RNAi).
The dsRNAs of the present invention can be used in gene-silencing. In one aspect, the invention provides methods to selectively degrade RNA using a dsRNAi of the present invention. The process may be practiced in vitro, ex vivo or in vivo. In one aspect, the dsRNA molecules can be used to generate a loss-of-function mutation in a cell, an organ or an animal. Methods for making and using dsRNA molecules to selectively degrade RNA are well known in the art; see, for example, U.S. Pat. Nos. 6,489,127; 6,506,559; 6,511,824; and 6,515,109.
The present invention further relates to a mutant cell of a parent cell that comprises a disruption or deletion of a polynucleotide encoding the polypeptide or a control sequence thereof or a silenced gene encoding the polypeptide, which results in the mutant cell producing less of the polypeptide or no polypeptide compared to the parent cell.
The polypeptide-deficient mutant cells are particularly useful as host cells for expression of native and heterologous polypeptides. Therefore, the present invention further relates to methods of producing a native or heterologous polypeptide, comprising (a) cultivating the mutant cell under conditions conducive for production of the polypeptide; and (b) recovering the polypeptide. The term “heterologous polypeptides” means polypeptides that are not native to the host cell, e.g., a variant of a native protein. The host cell may comprise more than one copy of a polynucleotide encoding the native or heterologous polypeptide.
The methods used for cultivation and purification of the product of interest may be performed by methods known in the art.
The methods of the present invention for producing an essentially xylanase-free product are of particular interest in the production of eukaryotic polypeptides, in particular fungal proteins such as enzymes. The xylanase-deficient cells may also be used to express heterologous proteins of pharmaceutical interest such as hormones, growth factors, receptors, and the like. The term “eukaryotic polypeptides” includes not only native polypeptides, but also those polypeptides, e.g., enzymes, which have been modified by amino acid substitutions, deletions or additions, or other such modifications to enhance activity, thermostability, pH tolerance and the like.
In a further aspect, the present invention relates to a protein product essentially free from xylanase activity that is produced by a method of the present invention.
Fermentation Broth Formulations or Cell Compositions
The present invention also relates to a fermentation broth formulation or a cell composition comprising a polypeptide of the present invention. The fermentation broth product further comprises additional ingredients used in the fermentation process, such as, for example, cells (including, the host cells containing the gene encoding the polypeptide of the present invention which are used to produce the polypeptide of interest), cell debris, biomass, fermentation media and/or fermentation products. In some embodiments, the composition is a cell-killed whole broth containing organic acid(s), killed cells and/or cell debris, and culture medium.
The term “fermentation broth” as used herein refers to a preparation produced by cellular fermentation that undergoes no or minimal recovery and/or purification. For example, fermentation broths are produced when microbial cultures are grown to saturation, incubated under carbon-limiting conditions to allow protein synthesis (e.g., expression of enzymes by host cells) and secretion into cell culture medium. The fermentation broth can contain unfractionated or fractionated contents of the fermentation materials derived at the end of the fermentation. Typically, the fermentation broth is unfractionated and comprises the spent culture medium and cell debris present after the microbial cells (e.g., filamentous fungal cells) are removed, e.g., by centrifugation. In some embodiments, the fermentation broth contains spent cell culture medium, extracellular enzymes, and viable and/or nonviable microbial cells.
In an embodiment, the fermentation broth formulation and cell compositions comprise a first organic acid component comprising at least one 1-5 carbon organic acid and/or a salt thereof and a second organic acid component comprising at least one 6 or more carbon organic acid and/or a salt thereof. In a specific embodiment, the first organic acid component is acetic acid, formic acid, propionic acid, a salt thereof, or a mixture of two or more of the foregoing and the second organic acid component is benzoic acid, cyclohexanecarboxylic acid, 4-methylvaleric acid, phenylacetic acid, a salt thereof, or a mixture of two or more of the foregoing.
In one aspect, the composition contains an organic acid(s), and optionally further contains killed cells and/or cell debris. In one embodiment, the killed cells and/or cell debris are removed from a cell-killed whole broth to provide a composition that is free of these components.
The fermentation broth formulations or cell compostions may further comprise a preservative and/or anti-microbial (e.g., bacteriostatic) agent, including, but not limited to, sorbitol, sodium chloride, potassium sorbate, and others known in the art.
The fermentation broth formulations or cell compositions may further comprise multiple enzymatic activities, such as one or more (e.g., several) enzymes selected from the group consisting of a cellulase, a hemicellulase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin. The fermentation broth formulations or cell compositions may also comprise one or more (e.g., several) enzymes selected from the group consisting of a hydrolase, an isomerase, a ligase, a lyase, an oxidoreductase, or a transferase, e.g., an alpha-galactosidase, alpha-glucosidase, aminopeptidase, amylase, beta-galactosidase, beta-glucosidase, beta-xylosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, glucoamylase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, or xylanase.
The cell-killed whole broth or composition may contain the unfractionated contents of the fermentation materials derived at the end of the fermentation. Typically, the cell-killed whole broth or composition contains the spent culture medium and cell debris present after the microbial cells (e.g., filamentous fungal cells) are grown to saturation, incubated under carbon-limiting conditions to allow protein synthesis (e.g., expression of cellulase and/or glucosidase enzyme(s)). In some embodiments, the cell-killed whole broth or composition contains the spent cell culture medium, extracellular enzymes, and killed filamentous fungal cells. In some embodiments, the microbial cells present in the cell-killed whole broth or composition can be permeabilized and/or lysed using methods known in the art.
A whole broth or cell composition as described herein is typically a liquid, but may contain insoluble components, such as killed cells, cell debris, culture media components, and/or insoluble enzyme(s). In some embodiments, insoluble components may be removed to provide a clarified liquid composition.
The whole broth formulations and cell compositions of the present invention may be produced by a method described in WO 90/15861 or WO 2010/096673.
Examples are given below of preferred uses of the compositions of the present invention. The dosage of the composition and other conditions under which the composition is used may be determined on the basis of methods known in the art.
Enzyme Compositions
The present invention also relates to compositions comprising a polypeptide of the present invention. Preferably, the compositions are enriched in such a polypeptide. The term “enriched” indicates that the xylanase activity of the composition has been increased, e.g., with an enrichment factor of at least 1.1.
The compositions may comprise a polypeptide of the present invention as the major enzymatic component, e.g., a mono-component composition. Alternatively, the compositions may comprise multiple enzymatic activities, such as one or more (e.g., several) enzymes selected from the group consisting of a cellulase, a hemicellulase, a GH61 polypeptide having cellulolytic enhancing activity, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin. The compositions may also comprise one or more (e.g., several) enzymes selected from the group consisting of a hydrolase, an isomerase, a ligase, a lyase, an oxidoreductase, or a transferase, e.g., an alpha-galactosidase, alpha-glucosidase, aminopeptidase, amylase, beta-galactosidase, beta-glucosidase, beta-xylosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, glucoamylase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, or xylanase.
The compositions may be prepared in accordance with methods known in the art and may be in the form of a liquid or a dry composition. The compositions may be stabilized in accordance with methods known in the art.
Examples are given below of preferred uses of the compositions of the present invention. The dosage of the composition and other conditions under which the composition is used may be determined on the basis of methods known in the art.
Uses
The present invention is also directed to the following processes for using the polypeptides having xylanase activity, or compositions thereof.
The present invention also relates to processes for degrading a cellulosic or xylan-containing material, comprising: treating the cellulosic or xylan-containing material with an enzyme composition in the presence of a polypeptide having xylanase activity of the present invention. In one aspect, the processes further comprise recovering the degraded cellulosic or xylan-containing material. Soluble products of degradation or conversion of the cellulosic or xylan-containing material can be separated from insoluble cellulosic or xylan-containing material using a method known in the art such as, for example, centrifugation, filtration, or gravity settling.
The present invention also relates to processes of producing a fermentation product, comprising: (a) saccharifying a cellulosic or xylan-containing material with an enzyme composition in the presence of a polypeptide having xylanase activity of the present invention; (b) fermenting the saccharified cellulosic or xylan-containing material with one or more (e.g., several) fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
The present invention also relates to processes of fermenting a cellulosic or xylan-containing material, comprising: fermenting the cellulosic or xylan-containing material with one or more (e.g., several) fermenting microorganisms, wherein the cellulosic or xylan-containing material is saccharified with an enzyme composition in the presence of a polypeptide having xylanase activity of the present invention. In one aspect, the fermenting of the cellulosic or xylan-containing material produces a fermentation product. In another aspect, the processes further comprise recovering the fermentation product from the fermentation.
The processes of the present invention can be used to saccharify the cellulosic or xylan-containing material to fermentable sugars and to convert the fermentable sugars to many useful fermentation products, e.g., fuel (ethanol, n-butanol, isobutanol, biodiesel, jet fuel) and/or platform chemicals (e.g., acids, alcohols, ketones, gases, oils, and the like). The production of a desired fermentation product from the cellulosic or xylan-containing material typically involves pretreatment, enzymatic hydrolysis (saccharification), and fermentation.
The processing of the cellulosic or xylan-containing material according to the present invention can be accomplished using methods conventional in the art. Moreover, the processes of the present invention can be implemented using any conventional biomass processing apparatus configured to operate in accordance with the invention.
Hydrolysis (saccharification) and fermentation, separate or simultaneous, include, but are not limited to, separate hydrolysis and fermentation (SHF); simultaneous saccharification and fermentation (SSF); simultaneous saccharification and co-fermentation (SSCF); hybrid hydrolysis and fermentation (HHF); separate hydrolysis and co-fermentation (SHCF); hybrid hydrolysis and co-fermentation (HHCF); and direct microbial conversion (DMC), also sometimes called consolidated bioprocessing (CBP). SHF uses separate process steps to first enzymatically hydrolyze the cellulosic material to fermentable sugars, e.g., glucose, cellobiose, and pentose monomers, and then ferment the fermentable sugars to ethanol. In SSF, the enzymatic hydrolysis of the cellulosic material and the fermentation of sugars to ethanol are combined in one step (Philippidis, G. P., 1996, Cellulose bioconversion technology, in Handbook on Bioethanol: Production and Utilization, Wyman, C. E., ed., Taylor & Francis, Washington, DC, 179-212). SSCF involves the co-fermentation of multiple sugars (Sheehan and Himmel, 1999, Biotechnol. Prog. 15: 817-827). HHF involves a separate hydrolysis step, and in addition a simultaneous saccharification and hydrolysis step, which can be carried out in the same reactor. The steps in an HHF process can be carried out at different temperatures, i.e., high temperature enzymatic saccharification followed by SSF at a lower temperature that the fermentation strain can tolerate. DMC combines all three processes (enzyme production, hydrolysis, and fermentation) in one or more (e.g., several) steps where the same organism is used to produce the enzymes for conversion of the cellulosic material to fermentable sugars and to convert the fermentable sugars into a final product (Lynd et al., 2002, Microbiol. Mol. Biol. Reviews 66: 506-577). It is understood herein that any method known in the art comprising pretreatment, enzymatic hydrolysis (saccharification), fermentation, or a combination thereof, can be used in the practicing the processes of the present invention.
A conventional apparatus can include a fed-batch stirred reactor, a batch stirred reactor, a continuous flow stirred reactor with ultrafiltration, and/or a continuous plug-flow column reactor (de Castilhos Corazza et al., 2003, Acta Scientiarum. Technology 25: 33-38; Gusakov and Sinitsyn, 1985, Enz. Microb. Technol. 7: 346-352), an attrition reactor (Ryu and Lee, 1983, Biotechnol. Bioeng. 25: 53-65). Additional reactor types include fluidized bed, upflow blanket, immobilized, and extruder type reactors for hydrolysis and/or fermentation.
Pretreatment. In practicing the processes of the present invention, any pretreatment process known in the art can be used to disrupt plant cell wall components of the cellulosic or xylan-containing material (Chandra et al., 2007, Adv. Biochem. Engin./Biotechnol. 108: 67-93; Galbe and Zacchi, 2007, Adv. Biochem. Engin./Biotechnol. 108: 41-65; Hendriks and Zeeman, 2009, Bioresource Technology 100: 10-18; Mosier et al., 2005, Bioresource Technology 96: 673-686; Taherzadeh and Karimi, 2008, Int. J. Mol. Sci. 9: 1621-1651; Yang and Wyman, 2008, Biofuels Bioproducts and Biorefining-Biofpr. 2: 26-40).
The cellulosic or xylan-containing material can also be subjected to particle size reduction, sieving, pre-soaking, wetting, washing, and/or conditioning prior to pretreatment using methods known in the art.
Conventional pretreatments include, but are not limited to, steam pretreatment (with or without explosion), dilute acid pretreatment, hot water pretreatment, alkaline pretreatment, lime pretreatment, wet oxidation, wet explosion, ammonia fiber explosion, organosolv pretreatment, and biological pretreatment. Additional pretreatments include ammonia percolation, ultrasound, electroporation, microwave, supercritical CO2, supercritical H2O, ozone, ionic liquid, and gamma irradiation pretreatments.
The cellulosic or xylan-containing material can be pretreated before hydrolysis and/or fermentation. Pretreatment is preferably performed prior to the hydrolysis. Alternatively, the pretreatment can be carried out simultaneously with enzyme hydrolysis to release fermentable sugars, such as glucose, xylose, and/or cellobiose. In most cases the pretreatment step itself results in some conversion of biomass to fermentable sugars (even in absence of enzymes).
Steam Pretreatment. In steam pretreatment, the cellulosic or xylan-containing material is heated to disrupt the plant cell wall components, including lignin, hemicellulose, and cellulose to make the cellulose and other fractions, e.g., hemicellulose, accessible to enzymes. The cellulosic or xylan-containing material is passed to or through a reaction vessel where steam is injected to increase the temperature to the required temperature and pressure and is retained therein for the desired reaction time. Steam pretreatment is preferably performed at 140-250° C., e.g., 160-200° C. or 170-190° C., where the optimal temperature range depends on optional addition of a chemical catalyst. Residence time for the steam pretreatment is preferably 1-60 minutes, e.g., 1-30 minutes, 1-20 minutes, 3-12 minutes, or 4-10 minutes, where the optimal residence time depends on the temperature and optional addition of a chemical catalyst. Steam pretreatment allows for relatively high solids loadings, so that the cellulosic or xylan-containing material is generally only moist during the pretreatment. The steam pretreatment is often combined with an explosive discharge of the material after the pretreatment, which is known as steam explosion, that is, rapid flashing to atmospheric pressure and turbulent flow of the material to increase the accessible surface area by fragmentation (Duff and Murray, 1996, Bioresource Technology 855: 1-33; Galbe and Zacchi, 2002, Appl. Microbiol. Biotechnol. 59: 618-628; U.S. Patent Application No. 2002/0164730). During steam pretreatment, hemicellulose acetyl groups are cleaved and the resulting acid autocatalyzes partial hydrolysis of the hemicellulose to monosaccharides and oligosaccharides. Lignin is removed to only a limited extent.
Chemical Pretreatment: The term “chemical treatment” refers to any chemical pretreatment that promotes the separation and/or release of cellulose, hemicellulose, and/or lignin. Such a pretreatment can convert crystalline cellulose to amorphous cellulose. Examples of suitable chemical pretreatment processes include, for example, dilute acid pretreatment, lime pretreatment, wet oxidation, ammonia fiber/freeze expansion (AFEX), ammonia percolation (APR), ionic liquid, and organosolv pretreatments.
A chemical catalyst such as H2SO4 or SO2 (typically 0.3 to 5% w/w) is sometimes added prior to steam pretreatment, which decreases the time and temperature, increases the recovery, and improves enzymatic hydrolysis (Ballesteros et al., 2006, Appl. Biochem. Biotechnol. 129-132: 496-508; Varga et al., 2004, Appl. Biochem. Biotechnol. 113-116: 509-523; Sassner et al., 2006, Enzyme Microb. Technol. 39: 756-762). In dilute acid pretreatment, the cellulosic material is mixed with dilute acid, typically H2SO4, and water to form a slurry, heated by steam to the desired temperature, and after a residence time flashed to atmospheric pressure. The dilute acid pretreatment can be performed with a number of reactor designs, e.g., plug-flow reactors, counter-current reactors, or continuous counter-current shrinking bed reactors (Duff and Murray, 1996, supra; Schell et al., 2004, Bioresource Technology 91: 179-188; Lee et al., 1999, Adv. Biochem. Eng. Biotechnol. 65: 93-115).
Several methods of pretreatment under alkaline conditions can also be used. These alkaline pretreatments include, but are not limited to, sodium hydroxide, lime, wet oxidation, ammonia percolation (APR), and ammonia fiber/freeze expansion (AFEX) pretreatment.
Lime pretreatment is performed with calcium oxide or calcium hydroxide at temperatures of 85-150° C. and residence times from 1 hour to several days (Wyman et al., 2005, Bioresource Technology 96: 1959-1966; Mosier et al., 2005, Bioresource Technology 96: 673-686). WO 2006/110891, WO 2006/110899, WO 2006/110900, and WO 2006/110901 disclose pretreatment methods using ammonia.
Wet oxidation is a thermal pretreatment performed typically at 180-200° C. for 5-15 minutes with addition of an oxidative agent such as hydrogen peroxide or over-pressure of oxygen (Schmidt and Thomsen, 1998, Bioresource Technology 64: 139-151; Palonen et al., 2004, Appl. Biochem. Biotechnol. 117: 1-17; Varga et al., 2004, Biotechnol. Bioeng. 88: 567-574; Martin et al., 2006, J. Chem. Technol. Biotechnol. 81: 1669-1677). The pretreatment is performed preferably at 1-40% dry matter, e.g., 2-30% dry matter or 5-20% dry matter, and often the initial pH is increased by the addition of alkali such as sodium carbonate.
A modification of the wet oxidation pretreatment method, known as wet explosion (combination of wet oxidation and steam explosion) can handle dry matter up to 30%. In wet explosion, the oxidizing agent is introduced during pretreatment after a certain residence time. The pretreatment is then ended by flashing to atmospheric pressure (WO 2006/032282).
Ammonia fiber expansion (AFEX) involves treating the cellulosic material with liquid or gaseous ammonia at moderate temperatures such as 90-150° C. and high pressure such as 17-20 bar for 5-10 minutes, where the dry matter content can be as high as 60% (Gollapalli et al., 2002, Appl. Biochem. Biotechnol. 98: 23-35; Chundawat et al., 2007, Biotechnol. Bioeng. 96: 219-231; Alizadeh et al., 2005, Appl. Biochem. Biotechnol. 121: 1133-1141; Teymouri et al., 2005, Bioresource Technology 96: 2014-2018). During AFEX pretreatment cellulose and hemicelluloses remain relatively intact. Lignin-carbohydrate complexes are cleaved.
Organosolv pretreatment delignifies the cellulosic material by extraction using aqueous ethanol (40-60% ethanol) at 160-200° C. for 30-60 minutes (Pan et al., 2005, Biotechnol. Bioeng. 90: 473-481; Pan et al., 2006, Biotechnol. Bioeng. 94: 851-861; Kurabi et al., 2005, Appl. Biochem. Biotechnol. 121: 219-230). Sulphuric acid is usually added as a catalyst. In organosolv pretreatment, the majority of hemicellulose and lignin is removed.
Other examples of suitable pretreatment methods are described by Schell et al., 2003, Appl. Biochem. Biotechnol. 105-108: 69-85, and Mosier et al., 2005, Bioresource Technology 96: 673-686, and U.S. application no. 2002/0164730.
In one aspect, the chemical pretreatment is preferably carried out as a dilute acid treatment, and more preferably as a continuous dilute acid treatment. The acid is typically sulfuric acid, but other acids can also be used, such as acetic acid, citric acid, nitric acid, phosphoric acid, tartaric acid, succinic acid, hydrogen chloride, or mixtures thereof. Mild acid treatment is conducted in the pH range of preferably 1-5, e.g., 1-4 or 1-2.5. In one aspect, the acid concentration is in the range from preferably 0.01 to 10 wt. % acid, e.g., 0.05 to 5 wt. % acid or 0.1 to 2 wt. % acid. The acid is contacted with the cellulosic or xylan-containing material and held at a temperature in the range of preferably 140-200° C., e.g., 165-190° C., for periods ranging from 1 to 60 minutes.
In another aspect, pretreatment takes place in an aqueous slurry. In preferred aspects, the cellulosic or xylan-containing material is present during pretreatment in amounts preferably between 10-80 wt. %, e.g., 20-70 wt. % or 30-60 wt. %, such as around 40 wt. %. The pretreated cellulosic or xylan-containing material can be unwashed or washed using any method known in the art, e.g., washed with water.
Mechanical Pretreatment or Physical Pretreatment: The term “mechanical pretreatment” or “physical pretreatment” refers to any pretreatment that promotes size reduction of particles. For example, such pretreatment can involve various types of grinding or milling (e.g., dry milling, wet milling, or vibratory ball milling).
The cellulosic or xylan-containing material can be pretreated both physically (mechanically) and chemically. Mechanical or physical pretreatment can be coupled with steaming/steam explosion, hydrothermolysis, dilute or mild acid treatment, high temperature, high pressure treatment, irradiation (e.g., microwave irradiation), or combinations thereof. In one aspect, high pressure means pressure in the range of preferably about 100 to about 400 psi, e.g., about 150 to about 250 psi. In another aspect, high temperature means temperature in the range of about 100 to about 300° C., e.g., about 140 to about 200° C. In a preferred aspect, mechanical or physical pretreatment is performed in a batch-process using a steam gun hydrolyzer system that uses high pressure and high temperature as defined above, e.g., a Sunds Hydrolyzer available from Sunds Defibrator AB, Sweden. The physical and chemical pretreatments can be carried out sequentially or simultaneously, as desired.
Accordingly, in a preferred aspect, the cellulosic or xylan-containing material is subjected to physical (mechanical) or chemical pretreatment, or any combination thereof, to promote the separation and/or release of cellulose, hemicellulose, and/or lignin.
Biological Pretreatment: The term “biological pretreatment” refers to any biological pretreatment that promotes the separation and/or release of cellulose, hemicellulose, and/or lignin from the cellulosic or xylan-containing material. Biological pretreatment techniques can involve applying lignin-solubilizing microorganisms and/or enzymes (see, for example, Hsu, T.-A., 1996, Pretreatment of biomass, in Handbook on Bioethanol: Production and Utilization, Wyman, C. E., ed., Taylor & Francis, Washington, DC, 179-212; Ghosh and Singh, 1993, Adv. Appl. Microbiol. 39: 295-333; McMillan, J. D., 1994, Pretreating lignocellulosic biomass: a review, in Enzymatic Conversion of Biomass for Fuels Production, Himmel, M. E., Baker, J. O., and Overend, R. P., eds., ACS Symposium Series 566, American Chemical Society, Washington, DC, chapter 15; Gong, C. S., Cao, N. J., Du, J., and Tsao, G. T., 1999, Ethanol production from renewable resources, in Advances in Biochemical Engineering/Biotechnology, Scheper, T., ed., Springer-Verlag Berlin Heidelberg, Germany, 65: 207-241; Olsson and Hahn-Hagerdal, 1996, Enz. Microb. Tech. 18: 312-331; and Vallander and Eriksson, 1990, Adv. Biochem. Eng./Biotechnol. 42: 63-95).
Saccharification.
In the hydrolysis step, also known as saccharification, the cellulosic or xylan-containing material, e.g., pretreated, is hydrolyzed to break down cellulose and/or hemicellulose to fermentable sugars, such as glucose, cellobiose, xylose, xylulose, arabinose, mannose, galactose, and/or soluble oligosaccharides. The hydrolysis is performed enzymatically by an enzyme composition in the presence of a polypeptide having xylanase activity of the present invention. The enzymes of the compositions can be added simultaneously or sequentially.
Enzymatic hydrolysis is preferably carried out in a suitable aqueous environment under conditions that can be readily determined by one skilled in the art. In one aspect, hydrolysis is performed under conditions suitable for the activity of the enzyme(s), i.e., optimal for the enzyme(s). The hydrolysis can be carried out as a fed batch or continuous process where the cellulosic or xylan-containing material is fed gradually to, for example, an enzyme containing hydrolysis solution.
The saccharification is generally performed in stirred-tank reactors or fermentors under controlled pH, temperature, and mixing conditions. Suitable process time, temperature and pH conditions can readily be determined by one skilled in the art. For example, the saccharification can last up to 200 hours, but is typically performed for preferably about 12 to about 120 hours, e.g., about 16 to about 72 hours or about 24 to about 48 hours. The temperature is in the range of preferably about 25° C. to about 70° C., e.g., about 30° C. to about 65° C., about 40° C. to about 60° C., or about 50° C. to about 55° C. The pH is in the range of preferably about 3 to about 8, e.g., about 3.5 to about 7, about 4 to about 6, or about 4.0 to about 5.5. The dry solids content is in the range of preferably about 5 to about 50 wt. %, e.g., about 10 to about 40 wt. % or about 20 to about 30 wt. %.
The enzyme compositions can comprise any protein useful in degrading the cellulosic or xylan-containing material.
In one aspect, the enzyme composition comprises or further comprises one or more (e.g., several) proteins selected from the group consisting of a cellulase, a GH61 polypeptide, a hemicellulase, an esterase, an expansin, a ligninolytic enzyme, an oxidoreductase, a pectinase, a protease, and a swollenin. In another aspect, the cellulase is preferably one or more (e.g., several) enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase. In another aspect, the hemicellulase is preferably one or more (e.g., several) enzymes selected from the group consisting of an acetylmannan esterase, an acetylxylan esterase, an arabinanase, an arabinofuranosidase, a coumaric acid esterase, a feruloyl esterase, a galactosidase, a glucuronidase, a glucuronoyl esterase, a mannanase, a mannosidase, a xylanase, and a xylosidase.
In another aspect, the enzyme composition comprises one or more (e.g., several) cellulolytic enzymes. In another aspect, the enzyme composition comprises or further comprises one or more (e.g., several) hemicellulolytic enzymes. In another aspect, the enzyme composition comprises one or more (e.g., several) cellulolytic enzymes and one or more (e.g., several) hemicellulolytic enzymes. In another aspect, the enzyme composition comprises one or more (e.g., several) enzymes selected from the group of cellulolytic enzymes and hemicellulolytic enzymes. In another aspect, the enzyme composition comprises an endoglucanase. In another aspect, the enzyme composition comprises a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase. In another aspect, the enzyme composition comprises a GH61 polypeptide. In another aspect, the enzyme composition comprises an endoglucanase and a GH61 polypeptide. In another aspect, the enzyme composition comprises a cellobiohydrolase and a GH61 polypeptide. In another aspect, the enzyme composition comprises a beta-glucosidase and a GH61 polypeptide. In another aspect, the enzyme composition comprises an endoglucanase and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase and a beta-glucosidase. In another aspect, the enzyme composition comprises a beta-glucosidase and a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II In another aspect, the enzyme composition comprises an endoglucanase, a GH61 polypeptide, and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase, a GH61 polypeptide, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a GH61 polypeptide. In another aspect, the enzyme composition comprises a beta-glucosidase, a GH61 polypeptide, and a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase, a GH61 polypeptide, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a cellobiohydrolase, a beta-glucosidase, and a GH61 polypeptide. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, a GH61 polypeptide, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II.
In another aspect, the enzyme composition comprises an acetylmannan esterase. In another aspect, the enzyme composition comprises an acetylxylan esterase. In another aspect, the enzyme composition comprises an arabinanase (e.g., alpha-L-arabinanase). In another aspect, the enzyme composition comprises an arabinofuranosidase (e.g., alpha-L-arabinofuranosidase). In another aspect, the enzyme composition comprises a coumaric acid esterase. In another aspect, the enzyme composition comprises a feruloyl esterase. In another aspect, the enzyme composition comprises a galactosidase (e.g., alpha-galactosidase and/or beta-galactosidase). In another aspect, the enzyme composition comprises a glucuronidase (e.g., alpha-D-glucuronidase). In another aspect, the enzyme composition comprises a glucuronoyl esterase. In another aspect, the enzyme composition comprises a mannanase. In another aspect, the enzyme composition comprises a mannosidase (e.g., beta-mannosidase). In another aspect, the enzyme composition comprises a xylanase. In a preferred aspect, the xylanase is a Family 10 xylanase. In another aspect, the enzyme composition comprises a xylosidase (e.g., beta-xylosidase).
In another aspect, the enzyme composition comprises an esterase. In another aspect, the enzyme composition comprises an expansin. In another aspect, the enzyme composition comprises a ligninolytic enzyme. In a preferred aspect, the ligninolytic enzyme is a manganese peroxidase. In another preferred aspect, the ligninolytic enzyme is a lignin peroxidase. In another preferred aspect, the ligninolytic enzyme is a H2O2-producing enzyme. In another aspect, the enzyme composition comprises a pectinase. In another aspect, the enzyme composition comprises an oxidoreductase. In another aspect, the enzyme composition comprises a protease. In another aspect, the enzyme composition comprises a swollenin.
In the processes of the present invention, the enzyme(s) can be added prior to or during saccharification, saccharification and fermentation, or fermentation.
One or more (e.g., several) components of the enzyme composition may be native proteins, recombinant proteins, or a combination of native proteins and recombinant proteins. For example, one or more (e.g., several) components may be native proteins of a cell, which is used as a host cell to express recombinantly one or more (e.g., several) other components of the enzyme composition. It is understood herein that the recombinant proteins may be heterologous (e.g., foreign) and native to the host cell. One or more (e.g., several) components of the enzyme composition may be produced as monocomponents, which are then combined to form the enzyme composition. The enzyme composition may be a combination of multicomponent and monocomponent protein preparations.
The enzymes used in the processes of the present invention may be in any form suitable for use, such as, for example, a fermentation broth formulation or a cell composition, a cell lysate with or without cellular debris, a semi-purified or purified enzyme preparation, or a host cell as a source of the enzymes. The enzyme composition may be a dry powder or granulate, a non-dusting granulate, a liquid, a stabilized liquid, or a stabilized protected enzyme. Liquid enzyme preparations may, for instance, be stabilized by adding stabilizers such as a sugar, a sugar alcohol or another polyol, and/or lactic acid or another organic acid according to established processes.
The optimum amounts of the enzymes and polypeptides having xylanase activity depend on several factors including, but not limited to, the mixture of cellulolytic enzymes and/or hemicellulolytic enzymes, the cellulosic or xylan-containing material, the concentration of cellulosic or xylan-containing material, the pretreatment(s) of the cellulosic or xylan-containing material, temperature, time, pH, and inclusion of a fermenting organism (e.g., for Simultaneous Saccharification and Fermentation.
In one aspect, an effective amount of cellulolytic or hemicellulolytic enzyme to the cellulosic or xylan-containing material is about 0.5 to about 50 mg, e.g., about 0.5 to about 40 mg, about 0.5 to about 25 mg, about 0.75 to about 20 mg, about 0.75 to about 15 mg, about 0.5 to about 10 mg, or about 2.5 to about 10 mg per g of the cellulosic or xylan-containing material.
In another aspect, an effective amount of a polypeptide having xylanase activity to the cellulosic or xylan-containing material is about 0.01 to about 50.0 mg, e.g., about 0.01 to about 40 mg, about 0.01 to about 30 mg, about 0.01 to about 20 mg, about 0.01 to about 10 mg, about 0.01 to about 5 mg, about 0.025 to about 1.5 mg, about 0.05 to about 1.25 mg, about 0.075 to about 1.25 mg, about 0.1 to about 1.25 mg, about 0.15 to about 1.25 mg, or about 0.25 to about 1.0 mg per g of the cellulosic or xylan-containing material.
In another aspect, an effective amount of a polypeptide having xylanase activity to cellulolytic or hemicellulolytic enzyme is about 0.005 to about 1.0 g, e.g., about 0.01 to about 1.0 g, about 0.15 to about 0.75 g, about 0.15 to about 0.5 g, about 0.1 to about 0.5 g, about 0.1 to about 0.25 g, or about 0.05 to about 0.2 g per g of cellulolytic or hemicellulolytic enzyme.
The polypeptides having cellulolytic enzyme activity or hemicellulolytic enzyme activity as well as other proteins/polypeptides useful in the degradation of the cellulosic or xylan-containing material (collectively hereinafter “polypeptides having enzyme activity”) can be derived or obtained from any suitable origin, including, archaeal, bacterial, fungal, yeast, plant, or animal origin. The term “obtained” also means herein that the enzyme may have been produced recombinantly in a host organism employing methods described herein, wherein the recombinantly produced enzyme is either native or foreign to the host organism or has a modified amino acid sequence, e.g., having one or more (e.g., several) amino acids that are deleted, inserted and/or substituted, i.e., a recombinantly produced enzyme that is a mutant and/or a fragment of a native amino acid sequence or an enzyme produced by nucleic acid shuffling processes known in the art. Encompassed within the meaning of a native enzyme are natural variants and within the meaning of a foreign enzyme are variants obtained by, e.g., site-directed mutagenesis or shuffling.
A polypeptide having enzyme activity may be a bacterial polypeptide. For example, the polypeptide may be a Gram-positive bacterial polypeptide having enzyme activity, or a Gram-negative bacterial polypeptide having enzyme activity.
The polypeptide having enzyme activity may also be a fungal polypeptide, and more preferably a yeast polypeptide having enzyme activity or more preferably a filamentous fungal polypeptide having enzyme activity.
Chemically modified or protein engineered mutants of polypeptides having enzyme activity may also be used.
One or more (e.g., several) components of the enzyme composition may be a recombinant component, i.e., produced by cloning of a DNA sequence encoding the single component and subsequent cell transformed with the DNA sequence and expressed in a host (see, for example, WO 91/17243 and WO 91/17244). The host is preferably a heterologous host (enzyme is foreign to host), but the host may under certain conditions also be a homologous host (enzyme is native to host). Monocomponent cellulolytic proteins may also be prepared by purifying such a protein from a fermentation broth.
In one aspect, the one or more (e.g., several) cellulolytic enzymes comprise a commercial cellulolytic enzyme preparation. Examples of commercial cellulolytic enzyme preparations suitable for use in the present invention include, for example, CELLIC® CTec (Novozymes A/S), CELLIC® CTec2 (Novozymes A/S), CELLIC® CTec3 (Novozymes A/S), CELLUCLASTTM (Novozymes A/S), NOVOZYMTM 188 (Novozymes A/S), SPEZYMETM CP (Genencor Int.), ACCELERASETM TRIO (DuPont), FILTRASE® NL (DSM); METHAPLUS® S/L 100 (DSM), ROHAMENTTM 7069 W (Röhm GmbH), or ALTERNAFUEL® CMAX3TM (Dyadic International, Inc.). The cellulase enzymes are added in amounts effective from about 0.001 to about 5.0 wt. % of solids, e.g., about 0.025 to about 4.0 wt. % of solids or about 0.005 to about 2.0 wt. % of solids.
Examples of bacterial endoglucanases that can be used in the processes of the present invention, include, but are not limited to, Acidothermus cellulolyticus endoglucanase (WO 91/05039; WO 93/15186; U.S. Pat. No. 5,275,944; WO 96/02551; U.S. Pat. No. 5,536,655; WO 00/70031; WO 05/093050), Erwinia carotovara endoglucanase (Saarilahti et al., 1990, Gene 90: 9-14), Thermobifida fusca endoglucanase III (WO 05/093050), and Thermobifida fusca endoglucanase V (WO 05/093050).
Examples of fungal endoglucanases that can be used in the present invention, include, but are not limited to, Trichoderma reesei endoglucanase I (Penttila et al., 1986, Gene 45: 253-263, Trichoderma reesei Cel7B endoglucanase I (GenBank:M15665), Trichoderma reesei endoglucanase II (Saloheimo et al., 1988, Gene 63:11-22), Trichoderma reesei Cel5A endoglucanase II (GenBank:M19373), Trichoderma reesei endoglucanase III (Okada et al., 1988, Appl. Environ. Microbiol. 64: 555-563, GenBank:AB003694), Trichoderma reesei endoglucanase V (Saloheimo et al., 1994, Molecular Microbiology 13: 219-228, GenBank:Z33381), Aspergillus aculeatus endoglucanase (Ooi et al., 1990, Nucleic Acids Research 18: 5884), Aspergillus kawachii endoglucanase (Sakamoto et al., 1995, Current Genetics 27: 435-439), Fusarium oxysporum endoglucanase (GenBank:L29381), Humicola grisea var. thermoidea endoglucanase (GenBank:AB003107), Melanocarpus albomyces endoglucanase (GenBank:MAL515703), Neurospora crassa endoglucanase (GenBank:XM_324477), Humicola insolens endoglucanase V, Myceliophthora thermophila CBS 117.65 endoglucanase, Thermoascus aurantiacus endoglucanase I (GenBank:AF487830) and Trichoderma reesei strain No. VTT-D-80133 endoglucanase (GenBank:M15665).
Examples of cellobiohydrolases useful in the present invention include, but are not limited to, Aspergillus aculeatus cellobiohydrolase II (WO 2011/059740), Chaetomium thermophilum cellobiohydrolase I, Chaetomium thermophilum cellobiohydrolase II, Humicola insolens cellobiohydrolase I, Myceliophthora thermophila cellobiohydrolase II (WO 2009/042871), Penicillium occitanis cellobiohydrolase I (GenBank:AY690482), Talaromyces emersonii cellobiohydrolase I (GenBank:AF439936), Thielavia hyrcanie cellobiohydrolase II (WO 2010/141325), Thielavia terrestris cellobiohydrolase II (CEL6A, WO 2006/074435), Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, and Trichophaea saccata cellobiohydrolase II (WO 2010/057086).
Examples of beta-glucosidases useful in the present invention include, but are not limited to, beta-glucosidases from Aspergillus aculeatus (Kawaguchi et al., 1996, Gene 173: 287-288), Aspergillus fumigatus (WO 2005/047499), Aspergillus niger (Dan et al., 2000, J. Biol. Chem. 275: 4973-4980), Aspergillus oryzae (WO 02/095014), Penicillium brasilianum IBT 20888 (WO 2007/019442 and WO 2010/088387), Thielavia terrestris (WO 2011/035029), and Trichophaea saccata (WO 2007/019442).
Other useful endoglucanases, cellobiohydrolases, and beta-glucosidases are disclosed in numerous Glycosyl Hydrolase families using the classification according to Henrissat, 1991, Biochem. J. 280: 309-316, and Henrissat and Bairoch, 1996, Biochem. J. 316: 695-696.
In the processes of the present invention, any GH61 polypeptide having cellulolytic enhancing activity can be used as a component of the enzyme composition.
Examples of GH61 polypeptides useful in the processes of the present invention include, but are not limited to, GH61 polypeptides from Thielavia terrestris (WO 2005/074647, WO 2008/148131, and WO 2011/035027), Thermoascus aurantiacus (WO 2005/074656 and WO 2010/065830), Trichoderma reesei (WO 2007/089290), Myceliophthora thermophila (WO 2009/085935, WO 2009/085859, WO 2009/085864, and WO 2009/085868), Aspergillus fumigatus (WO 2010/138754), Penicillium pinophilum (WO 2011/005867), Thermoascus sp. (WO 2011/039319), Penicillium sp. (WO 2011/041397), Thermoascus crustaceous (WO 2011/041504), Aspergillus aculeatus (WO 2012/125925), Thermomyces lanuginosus (WO 2012/113340, WO 12/129699, and WO 2012/130964), Aurantiporus alborubescens (WO 2012/122477), Trichophaea saccata (WO 2012/122477), Penicillium thomii (WO 2012/122477), Talaromyces stipitatus (WO 2012/135659), Humicola insolens (WO 2012/146171), Maibranchea cinnamomea (WO 2012/101206), Talaromyces leycettanus (WO 2012/101206), and Chaetomium thermophilum (WO 2012/101206).
In one aspect, the GH61 polypeptide is used in the presence of a soluble activating divalent metal cation according to WO 2008/151043, e.g., manganese or copper.
In another aspect, the GH61 polypeptide is used in the presence of a dioxy compound, a bicylic compound, a heterocyclic compound, a nitrogen-containing compound, a quinone compound, a sulfur-containing compound, or a liquor obtained from a pretreated cellulosic material such as pretreated corn stover (WO 2012/021394, WO 2012/021395, WO 2012/021396, WO 2012/021399, WO 2012/021400, WO 2012/021401, WO 2012/021408, and WO 2012/021410).
In one aspect, such a compound is added at a molar ratio of the compound to glucosyl units of cellulose of about 10−6 to about 10, e.g., about 10−6 to about 7.5, about 10−6 to about 5, about 10−6 to about 2.5, about 10−6 to about 1, about 10−5 to about 1, about 10−5 to about 10−1, about 10−4 to about 10−1, about 10−3 to about 10−1, or about 10−3 to about 10−2. In another aspect, an effective amount of such a compound is about 0.1 μM to about 1 M, e.g., about 0.5 μM to about 0.75 M, about 0.75 μM to about 0.5 M, about 1 μM to about 0.25 M, about 1 μM to about 0.1 M, about 5 μM to about 50 mM, about 10 μM to about 25 mM, about 50 μM to about 25 mM, about 10 μM to about 10 mM, about 5 μM to about 5 mM, or about 0.1 mM to about 1 mM.
The term “liquor” means the solution phase, either aqueous, organic, or a combination thereof, arising from treatment of a lignocellulose and/or hemicellulose material in a slurry, or monosaccharides thereof, e.g., xylose, arabinose, mannose, etc., under conditions as described herein, and the soluble contents thereof. A liquor for cellulolytic enhancement of a GH61 polypeptide can be produced by treating a lignocellulose or hemicellulose material (or feedstock) by applying heat and/or pressure, optionally in the presence of a catalyst, e.g., acid, optionally in the presence of an organic solvent, and optionally in combination with physical disruption of the material, and then separating the solution from the residual solids. Such conditions determine the degree of cellulolytic enhancement obtainable through the combination of liquor and a GH61 polypeptide during hydrolysis of a cellulosic substrate by a cellulase preparation. The liquor can be separated from the treated material using a method standard in the art, such as filtration, sedimentation, or centrifugation.
In one aspect, an effective amount of the liquor to cellulose is about 10−6 to about 10 g per g of cellulose, e.g., about 10−6 to about 7.5 g, about 10−6 to about 5 g, about 10−6 to about 2.5 g, about 10−6 to about 1 g, about 10−5 to about 1 g, about 10−5 to about 10−1 g, about 10−4 to about 10−1 g, about 10−3 to about 10−1 g, or about 10−3 to about 10−2 g per g of cellulose.
In one aspect, the one or more (e.g., several) hemicellulolytic enzymes comprise a commercial hemicellulolytic enzyme preparation. Examples of commercial hemicellulolytic enzyme preparations suitable for use in the present invention include, for example, SHEARZYMETM (Novozymes A/S), CELLIC® HTec (Novozymes A/S), CELLIC® HTec2 (Novozymes A/S), CELLIC® HTec3 (Novozymes A/S), VISCOZYME® (Novozymes A/S), ULTRAFLO® (Novozymes A/S), PULPZYME® HC (Novozymes A/S), MULTIFECT® Xylanase (Genencor), ACCELLERASE® XY (Genencor), ACCELLERASE® XC (Genencor), ECOPULP® TX-200A (AB Enzymes), HSP 6000 Xylanase (DSM), DEPOLTM 333P (Biocatalysts Limit, Wales, UK), DEPOLTM 740L (Biocatalysts Limit, Wales, UK), and DEPOLTM 762P (Biocatalysts Limit, Wales, UK), ALTERNA FUEL 100P (Dyadic), and ALTERNA FUEL 200P (Dyadic).
Examples of xylanases useful in the processes of the present invention include, but are not limited to, xylanases from Aspergillus aculeatus (GeneSeqP:AAR63790; WO 94/21785), Aspergillus fumigatus (WO 2006/078256), Penicillium pinophilum (WO 2011/041405), Penicillium sp. (WO 2010/126772), Talaromyces lanuginosus GH11 (WO 2012/130965), Talaromyces thermophilus GH11 (WO 2012/13095), Thielavia terrestris NRRL 8126 (WO 2009/079210), and Trichophaea saccata GH10 (WO 2011/057083).
Examples of beta-xylosidases useful in the processes of the present invention include, but are not limited to, beta-xylosidases from Neurospora crassa (SwissProt:Q7SOW4), Trichoderma reesei (UniProtKB/TrEMBL:Q92458), Talaromyces emersonii (SwissProt:Q8X212), and Talaromyces thermophilus GH11 (WO 2012/130965).
Examples of acetylxylan esterases useful in the processes of the present invention include, but are not limited to, acetylxylan esterases from Aspergillus aculeatus (WO 2010/108918), Chaetomium globosum (UniProt:Q2GVVX4), Chaetomium gracile (GeneSeqP:AAB82124), Humicola insolens DSM 1800 (WO 2009/073709), Hypocrea jecorina (WO 2005/001036), Myceliophtera thermophila (WO 2010/014880), Neurospora crassa (Uni Prot: q7s259), Phaeosphaeria nodorum (UniProt:Q0UHJ1), and Thielavia terrestris NRRL 8126 (WO 2009/042846).
Examples of feruloyl esterases (ferulic acid esterases) useful in the processes of the present invention include, but are not limited to, feruloyl esterases form Humicola insolens DSM 1800 (WO 2009/076122), Neosartorya fischeri (UniProt:A1D9T4), Neurospora crassa (UniProt:Q9HGR3), Penicillium aurantiogriseum (WO 2009/127729), and Thielavia terrestris (WO 2010/053838 and WO 2010/065448).
Examples of arabinofuranosidases useful in the processes of the present invention include, but are not limited to, arabinofuranosidases from Aspergillus niger (GeneSeqP:AAR94170), Humicola insolens DSM 1800 (WO 2006/114094 and WO 2009/073383), and M. giganteus (WO 2006/114094).
Examples of alpha-glucuronidases useful in the processes of the present invention include, but are not limited to, alpha-glucuronidases from Aspergillus clavatus (UniProt:alcc12), Aspergillus fumigatus (SwissProt:Q4VWV45), Aspergillus niger (UniProt:Q96WX9), Aspergillus terreus (SwissProt: Q0CJP9), Humicola insolens (WO 2010/014706), Penicillium aurantiogriseum (WO 2009/068565), Talaromyces emersonii (UniProt:Q8X211), and Trichoderma reesei (UniProt:Q99024).
The polypeptides having enzyme activity used in the processes of the present invention may be produced by fermentation of the above-noted microbial strains on a nutrient medium containing suitable carbon and nitrogen sources and inorganic salts, using procedures known in the art (see, e.g., Bennett, J. W. and LaSure, L. (eds.), More Gene Manipulations in Fungi, Academic Press, C A, 1991). Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). Temperature ranges and other conditions suitable for growth and enzyme production are known in the art (see, e.g., Bailey, J. E., and Ollis, D. F., Biochemical Engineering Fundamentals, McGraw-Hill Book Company, N Y, 1986).
The fermentation can be any method of cultivation of a cell resulting in the expression or isolation of an enzyme or protein. Fermentation may, therefore, be understood as comprising shake flask cultivation, or small- or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermentors performed in a suitable medium and under conditions allowing the enzyme to be expressed or isolated. The resulting enzymes produced by the methods described above may be recovered from the fermentation medium and purified by conventional procedures.
Fermentation.
The fermentable sugars obtained from the hydrolyzed cellulosic or xylan-containing material can be fermented by one or more (e.g., several) fermenting microorganisms capable of fermenting the sugars directly or indirectly into a desired fermentation product. “Fermentation” or “fermentation process” refers to any fermentation process or any process comprising a fermentation step. Fermentation processes also include fermentation processes used in the consumable alcohol industry (e.g., beer and wine), dairy industry (e.g., fermented dairy products), leather industry, and tobacco industry. The fermentation conditions depend on the desired fermentation product and fermenting organism and can easily be determined by one skilled in the art.
In the fermentation step, sugars, released from the cellulosic or xylan-containing material as a result of the pretreatment and enzymatic hydrolysis steps, are fermented to a product, e.g., ethanol, by a fermenting organism, such as yeast. Hydrolysis (saccharification) and fermentation can be separate or simultaneous.
Any suitable hydrolyzed cellulosic material can be used in the fermentation step in practicing the present invention. The material is generally selected based on economics, i.e., costs per equivalent sugar potential, and recalcitrance to enzymatic conversion.
The term “fermentation medium” is understood herein to refer to a medium before the fermenting microorganism(s) is(are) added, such as, a medium resulting from a saccharification process, as well as a medium used in a simultaneous saccharification and fermentation process (SSF).
“Fermenting microorganism” refers to any microorganism, including bacterial and fungal organisms, suitable for use in a desired fermentation process to produce a fermentation product. The fermenting organism can be hexose and/or pentose fermenting organisms, or a combination thereof. Both hexose and pentose fermenting organisms are well known in the art. Suitable fermenting microorganisms are able to ferment, i.e., convert, sugars, such as glucose, xylose, xylulose, arabinose, maltose, mannose, galactose, and/or oligosaccharides, directly or indirectly into the desired fermentation product. Examples of bacterial and fungal fermenting organisms producing ethanol are described by Lin et al., 2006, Appl. Microbiol. Biotechnol. 69: 627-642.
Examples of fermenting microorganisms that can ferment hexose sugars include bacterial and fungal organisms, such as yeast. Yeast include strains of Candida, Kluyveromyces, and Saccharomyces, e.g., Candida sonorensis, Kluyveromyces marxianus, and Saccharomyces cerevisiae. 
Examples of fermenting organisms that can ferment pentose sugars in their native state include bacterial and fungal organisms, such as some yeast. Xylose fermenting yeast include strains of Candida, preferably C. sheatae or C. sonorensis; and strains of Pichia, e.g., P. stipitis, such as P. stipitis CBS 5773. Pentose fermenting yeast include strains of Pachysolen, preferably P. tannophilus. Organisms not capable of fermenting pentose sugars, such as xylose and arabinose, may be genetically modified to do so by methods known in the art.
Examples of bacteria that can efficiently ferment hexose and pentose to ethanol include, for example, Bacillus coagulans, Clostridium acetobutylicum, Clostridium thermocellum, Clostridium phytofermentans, Geobacillus sp., Thermoanaerobacter saccharolyticum, and Zymomonas mobilis (Philippidis, 1996, supra).
Other fermenting organisms include strains of Bacillus, such as Bacillus coagulans; Candida, such as C. sonorensis, C. methanosorbosa, C. diddensiae, C. parapsilosis, C. naedodendra, C. blankii, C. entomophilia, C. brassicae, C. pseudotropicalis, C. boidinii, C. utilis, and C. scehatae; Clostridium, such as C. acetobutylicum, C. thermocellum, and C. phytofermentans; E. coli, especially E. coli strains that have been genetically modified to improve the yield of ethanol; Geobacillus sp.; Hansenula, such as Hansenula anomala; Klebsiella, such as K. oxytoca; Kluyveromyces, such as K. marxianus, K. lactis, K. thermotolerans, and K. fragilis; Schizosaccharomyces, such as S. pombe; Thermoanaerobacter, such as Thermoanaerobacter saccharolyticum; and Zymomonas, such as Zymomonas mobilis. 
Commercially available yeast suitable for ethanol production include, e.g., BIOFERMTM AFT and XR (NABC—North American Bioproducts Corporation, GA, USA), ETHANOL REDTM yeast (Fermentis/Lesaffre, USA), FALITM (Fleischmann's Yeast, USA), FERMIOLTM (DSM Specialties), GERT STRANDTM (Gert Strand AB, Sweden), and SUPERSTARTTM and THERMOSACCTM fresh yeast (Ethanol Technology, WI, USA).
In an aspect, the fermenting microorganism has been genetically modified to provide the ability to ferment pentose sugars, such as xylose utilizing, arabinose utilizing, and xylose and arabinose co-utilizing microorganisms.
The cloning of heterologous genes into various fermenting microorganisms has led to the construction of organisms capable of converting hexoses and pentoses to ethanol (co-fermentation) (Chen and Ho, 1993, Appl. Biochem. Biotechnol. 39-40: 135-147; Ho et al., 1998, Appl. Environ. Microbiol. 64: 1852-1859; Kotter and Ciriacy, 1993, Appl. Microbiol. Biotechnol. 38: 776-783; Walfridsson et al., 1995, Appl. Environ. Microbiol. 61: 4184-4190; Kuyper et al., 2004, FEMS Yeast Research 4: 655-664; Beall et al., 1991, Biotech. Bioeng. 38: 296-303; Ingram et al., 1998, Biotechnol. Bioeng. 58: 204-214; Zhang et al., 1995, Science 267: 240-243; Deanda et al., 1996, Appl. Environ. Microbiol. 62: 4465-4470; WO 03/062430).
It is well known in the art that the organisms described above can also be used to produce other substances, as described herein.
The fermenting microorganism is typically added to the degraded cellulosic material or hydrolysate and the fermentation is performed for about 8 to about 96 hours, e.g., about 24 to about 60 hours. The temperature is typically between about 26° C. to about 60° C., e.g., about 32° C. or 50° C., and about pH 3 to about pH 8, e.g., pH 4-5, 6, or 7.
In one aspect, the yeast and/or another microorganism are applied to the degraded cellulosic material and the fermentation is performed for about 12 to about 96 hours, such as typically 24-60 hours. In another aspect, the temperature is preferably between about 20° C. to about 60° C., e.g., about 25° C. to about 50° C., about 32° C. to about 50° C., or about 32° C. to about 50° C., and the pH is generally from about pH 3 to about pH 7, e.g., about pH 4 to about pH 7. However, some fermenting organisms, e.g., bacteria, have higher fermentation temperature optima. Yeast or another microorganism is preferably applied in amounts of approximately 105 to 1012, preferably from approximately 107 to 1010, especially approximately 2×108 viable cell count per ml of fermentation broth. Further guidance in respect of using yeast for fermentation can be found in, e.g., “The Alcohol Textbook” (Editors K. Jacques, T. P. Lyons and D. R. Kelsall, Nottingham University Press, United Kingdom 1999), which is hereby incorporated by reference.
A fermentation stimulator can be used in combination with any of the processes described herein to further improve the fermentation process, and in particular, the performance of the fermenting microorganism, such as, rate enhancement and ethanol yield. A “fermentation stimulator” refers to stimulators for growth of the fermenting microorganisms, in particular, yeast. Preferred fermentation stimulators for growth include vitamins and minerals. Examples of vitamins include multivitamins, biotin, pantothenate, nicotinic acid, meso-inositol, thiamine, pyridoxine, para-aminobenzoic acid, folic acid, riboflavin, and Vitamins A, B, C, D, and E. See, for example, Alfenore et al., Improving ethanol production and viability of Saccharomyces cerevisiae by a vitamin feeding strategy during fed-batch process, Springer-Verlag (2002), which is hereby incorporated by reference. Examples of minerals include minerals and mineral salts that can supply nutrients comprising P, K, Mg, S, Ca, Fe, Zn, Mn, and Cu.
Fermentation Products:
A fermentation product can be any substance derived from the fermentation. The fermentation product can be, without limitation, an alcohol (e.g., arabinitol, n-butanol, isobutanol, ethanol, glycerol, methanol, ethylene glycol, 1,3-propanediol [propylene glycol], butanediol, glycerin, sorbitol, and xylitol); an alkane (e.g., pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane), a cycloalkane (e.g., cyclopentane, cyclohexane, cycloheptane, and cyclooctane), an alkene (e.g. pentene, hexene, heptene, and octene); an amino acid (e.g., aspartic acid, glutamic acid, glycine, lysine, serine, and threonine); a gas (e.g., methane, hydrogen (H2), carbon dioxide (CO2), and carbon monoxide (CO)); isoprene; a ketone (e.g., acetone); an organic acid (e.g., acetic acid, acetonic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, glucaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, oxaloacetic acid, propionic acid, succinic acid, and xylonic acid); and polyketide. The fermentation product can also be protein as a high value product.
In a preferred aspect, the fermentation product is an alcohol. It will be understood that the term “alcohol” encompasses a substance that contains one or more hydroxyl moieties. The alcohol can be, but is not limited to, n-butanol, isobutanol, ethanol, methanol, arabinitol, butanediol, ethylene glycol, glycerin, glycerol, 1,3-propanediol, sorbitol, xylitol. See, for example, Gong et al., 1999, Ethanol production from renewable resources, in Advances in Biochemical Engineering/Biotechnology, Scheper, T., ed., Springer-Verlag Berlin Heidelberg, Germany, 65: 207-241; Silveira and Jonas, 2002, Appl. Microbiol. Biotechnol. 59: 400-408; Nigam and Singh, 1995, Process Biochemistry 30(2): 117-124; Ezeji et al., 2003, World Journal of Microbiology and Biotechnology 19(6): 595-603.
In another preferred aspect, the fermentation product is an alkane. The alkane may be an unbranched or a branched alkane. The alkane can be, but is not limited to, pentane, hexane, heptane, octane, nonane, decane, undecane, or dodecane.
In another preferred aspect, the fermentation product is a cycloalkane. The cycloalkane can be, but is not limited to, cyclopentane, cyclohexane, cycloheptane, or cyclooctane.
In another preferred aspect, the fermentation product is an alkene. The alkene may be an unbranched or a branched alkene. The alkene can be, but is not limited to, pentene, hexene, heptene, or octene.
In another preferred aspect, the fermentation product is an amino acid. The organic acid can be, but is not limited to, aspartic acid, glutamic acid, glycine, lysine, serine, or threonine. See, for example, Richard and Margaritis, 2004, Biotechnology and Bioengineering 87(4): 501-515.
In another preferred aspect, the fermentation product is a gas. The gas can be, but is not limited to, methane, H2, CO2, or CO. See, for example, Kataoka et al., 1997, Water Science and Technology 36(6-7): 41-47; and Gunaseelan, 1997, Biomass and Bioenergy 13(1-2): 83-114.
In another preferred aspect, the fermentation product is isoprene.
In another preferred aspect, the fermentation product is a ketone. It will be understood that the term “ketone” encompasses a substance that contains one or more ketone moieties. The ketone can be, but is not limited to, acetone.
In another preferred aspect, the fermentation product is an organic acid. The organic acid can be, but is not limited to, acetic acid, acetonic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, glucaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, propionic acid, succinic acid, or xylonic acid. See, for example, Chen and Lee, 1997, Appl. Biochem. Biotechnol. 63-65: 435-448.
In another preferred aspect, the fermentation product is polyketide.
Recovery.
The fermentation product(s) can be optionally recovered from the fermentation medium using any method known in the art including, but not limited to, chromatography, electrophoretic procedures, differential solubility, distillation, or extraction. For example, alcohol is separated from the fermented cellulosic material and purified by conventional methods of distillation. Ethanol with a purity of up to about 96 vol. % can be obtained, which can be used as, for example, fuel ethanol, drinking ethanol, i.e., potable neutral spirits, or industrial ethanol.
Signal Peptide
The present invention also relates to an isolated polynucleotide encoding a signal peptide comprising or consisting of amino acids 1 to 23 of SEQ ID NO: 2 or comprising or consisting of amino acids 1 to 23 of SEQ ID NO: 6. The polynucleotide may further comprise a gene encoding a protein, which is operably linked to the signal peptide. The protein is preferably foreign to the signal peptide. In one aspect, the polynucleotide encoding the signal peptide is nucleotides 1 to 156 of SEQ ID NO: 1. In another aspect, the polynucleotide encoding the signal peptide is nucleotides 1 to 150 of SEQ ID NO: 5.
The present invention also relates to nucleic acid constructs, expression vectors and recombinant host cells comprising such polynucleotides.
The present invention also relates to methods of producing a protein, comprising (a) cultivating a recombinant host cell comprising such polynucleotide; and optionally (b) recovering the protein.
The protein may be native or heterologous to a host cell. The term “protein” is not meant herein to refer to a specific length of the encoded product and, therefore, encompasses peptides, oligopeptides, and polypeptides. The term “protein” also encompasses two or more polypeptides combined to form the encoded product. The proteins also include hybrid polypeptides and fused polypeptides.
Preferably, the protein is a hormone, enzyme, receptor or portion thereof, antibody or portion thereof, or reporter. For example, the protein may be a hydrolase, isomerase, ligase, lyase, oxidoreductase, or transferase, e.g., an alpha-galactosidase, alpha-glucosidase, aminopeptidase, amylase, beta-galactosidase, beta-glucosidase, beta-xylosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, glucoamylase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, or xylanase.
The gene may be obtained from any prokaryotic, eukaryotic, or other source.
The present invention is further described by the following examples that should not be construed as limiting the scope of the invention.
EXAMPLES
Strains
Rasamsonia byssochlamydoides strains CBS 413.71 and CBS 150.75 were used as the source of GH10 polypeptides having xylanase activity. Aspergillus oryzae strain MT3568 was used for expression of the Rasamsonia byssochlamydoides genes encoding the polypeptides having xylanase activity. A. oryzae MT3568 is an amdS (acetamidase) disrupted gene derivative of Aspergillus oryzae JaL355 (WO 02/40694) in which pyrG auxotrophy was restored by disrupting the A. oryzae acetamidase (amdS) gene.
Media and Solutions
COVE sucrose plates were composed of 342 g of sucrose, 20 g of agar powder, 20 ml of COVE salt solution, and deionized water to 1 liter. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998). The medium was cooled to 60° C. and added 10 mM acetamide, 15 mM CsCl, Triton X-100 (50 μl/500 ml).
COVE salt solution was composed of 26 g of MgSO4.7H2O, 26 g of KCL, 26 g of KH2PO4, 50 ml of COVE trace metals solution, and deionized water to 1 liter.
COVE trace metals solution was composed of 0.04 g of Na2B4O7.10H2O, 0.4 g of CuSO4.5H2O, 1.2 g of FeSO4.7H2O, 0.7 g of MnSO4.H2O, 0.8 g of Na2MoO4.2H2O, 10 g of ZnSO4.7H2O, and deionized water to 1 liter.
Dap-4C medium was composed of 20 g of dextrose, 10 g of maltose, 11 g of MgSO4.7H2O, 1 g of KH2PO4, 2 g of citric acid, 5.2 g of K3PO4.H2O, 0.5 g of yeast extract (Difco), 1 ml of antifoam, 0.5 ml of KU6 trace metals solution, 2.5 g of CaCO3, and deionized water to 1 liter. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998). Before use, 3.5 ml of sterile 50% (NH4)2HPO4 and 5 ml of sterile 20% lactic acid were added per 150 ml of Dap-4C medium.
KU6 trace metals solution was composed of 0.13 g of NiCl2, 2.5 g of CuSO4.5H2O, 13.9 g of FeSO4.7H2O, 8.45 g MnSO4.H2O, 6.8 g ZnCl2, 3 g of citric acid, and deionized water to 1 liter.
LB plates were composed of 10 g of Bacto-Tryptone, 5 g of yeast extract, 10 g of sodium chloride, 15 g of Bacto-agar, and deionized water to 1 liter. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998).
PDA agar plates were composed of potato infusion made by boiling 300 g of sliced potatoes (washed but unpeeled) in water for 30 minutes and then decanting or straining the broth through cheesecloth. Distilled water was then added until the total volume of the suspension was one liter, followed by 20 g of dextrose and 20 g of agar powder. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998).
YP+2% glucose medium was composed of 1% yeast extract, 2% peptone, and 2% glucose in deionized water.
Example 1
Source of DNA Sequence Information for Rasamsonia byssochiamydoides CBS 413.71
Genomic sequence information was generated by Illumina DNA sequencing at Fasteris in Plan-les-Ouates, Switzerland from genomic DNA isolated from Rasamsonia byssochiamydoides CBS 413.71. A preliminary assembly of the genome was analyzed using GeneMark v2.3c (Georgia Tech's Center for Bioinformatics and Computational Genomics, Atlanta, Ga., USA). Gene models constructed by the software were used as a starting point for detecting GH10 homologs in the genome. More precise gene models were constructed manually using multiple known GH10 protein sequences as a guide.
Example 2
Rasamsonia byssochiamydoides CBS 413.71 and CBS 150.75 Genomic DNA Extraction
To generate genomic DNA for PCR amplification, Rasamsonia byssochiamydoides CBS 413.71 was propagated on PDA agar plates by growth at 26° C. for 7 days. Spores harvested from the PDA plates were used to inoculate 25 ml of YP+2% glucose medium in a baffled shake flask and incubated at 26° C. for 72 hours with agitation at 85 rpm.
To generate genomic DNA for PCR amplification, Rasamsonia byssochiamydoides CBS 150.75 was propagated on PDA agar plates by growth at 26° C. for 7 days. 50 mg of the fungal material was harvested with a scalpel by scraping off the surface of the PDA agar plate.
Genomic DNA from Rasamsonia byssochlamydoides CBS 413.71 was isolated according to a modified DNEASY® Plant Maxi Kit protocol (Qiagen Danmark, Copenhagen, Denmark). The fungal material from the above culture was harvested by centrifugation at 14,000×g for 2 minutes. The supernatant was removed and the pellet (0.5 g) was frozen in liquid nitrogen with quartz sand and ground to a fine powder in a pre-chilled mortar. The powder was transferred to a 15 ml centrifuge tube and 5 ml of AP1 buffer (Qiagen Danmark, Copenhagen, Denmark) preheated to 65° C. and 10 μl of RNase A stock solution (100 mg/ml) were added followed by vigorous vortexing. After incubation for 10 minutes at 65° C. with regular inverting of the tube, 1.8 ml of AP2 buffer (Qiagen Danmark, Copenhagen, Denmark) were added to the lysate by gentle mixing followed by incubation on ice for 10 minutes. The lysate was then centrifuged at 3000×g for 5 minutes at room temperature and the supernatant was decanted into a QIASHREDDERTM Maxi Spin Column (Qiagen Danmark, Copenhagen, Denmark), placed in a 50 ml collection tube, and centrifuged at 3000×g for 5 minutes at room temperature. The flow-through was transferred into a new 50 ml tube and 1.5 volume of AP3/E buffer (Qiagen Danmark, Copenhagen, Denmark) was added followed by vortexing. Fifteen ml of the sample were transferred to a DNEASY® Maxi Spin Column placed in a 50 ml collection tube and centrifuged at 3000×g for 5 minutes at room temperature. The flow-through was discarded and 12 ml of AW buffer (Qiagen Danmark, Copenhagen, Denmark) were added to the DNEASY® Maxi Spin Column placed in a 50 ml collection tube and centrifuged at 3000×g for 10 minutes at room temperature. After discarding the flow-through, centrifugation was repeated to dispose of the remaining alcohol. The DNEASY® Maxi Spin Column was transferred to a new 50 ml tube and 0.5 ml of AE buffer (Qiagen Danmark, Copenhagen, Denmark) preheated to 70° C. was added. After incubation for 5 minutes at room temperature, the sample was eluted by centrifugation at 3000×g for 5 minutes at room temperature. Elution was repeated with an additional 0.5 ml of AE buffer and the eluates were combined. The concentration of the harvested DNA was measured at 260 nm using a UV spectrophotometer.
Genomic DNA isolation from Rasamsonia byssochlamydoides CBS 150.75 was carried out using the Maxwell® 16 Instrument according to the Maxwell® 16 DNA Purification Kits protocol (TH. Geyer Danmark Aps, Roskilde, Denmark). The genomic DNA was elution with 300 μl elution buffer. The concentration of the harvested DNA was measured at 260 nm using a UV spectrophotometer.
Example 3
Construction of an Aspergillus oryzae Expression Vector Containing Rasamsonia byssochlamydoides Strain CBS413.71 Genomic Sequence Encoding a Family GH10 Polypeptide Having Xylanase Activity
Two synthetic oligonucleotide primers, shown below, were designed to PCR amplify the Rasamsonia byssochlamydoides CBS 413.71 P24GTR gene (SEQ ID NO: 1) and the Rasamsonia byssochiamydoides CBS 150.75 P34RRZ gene (SEQ ID NO: 5) from the genomic DNA prepared in Example 2. An IN-FUSIONTM Cloning Kit (BD Biosciences, Palo Alto, Calif., USA) was used to clone the fragment directly into the expression vector pDau109 (WO 2005/042735).
Primer F-P24GTR
5′-ACACAACTGGGGATCCACCATGATGGTTCGCAACCTTCCAGTC-3′ (SEQ ID NO: 3)
Primer R-P24GTR
5′-CCCTCTAGATCTCGAGTCACAGACACTGCGAGTAATATGGATTGA-3′ (SEQ ID NO: 4)
Bold letters represent gene sequence. The underlined sequence is homologous to the insertion sites of pDau109.
A PHUSION® High-Fidelity PCR Kit (Finnzymes Oy, Espoo, Finland) was used for the PCR amplification. The PCR was composed of 5 μl of 5×HF buffer (Finnzymes Oy, Espoo, Finland), 0.5 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl) (Finnzymes Oy, Espoo, Finland), 2 μl of primer F-P24GTR (2.5 μM), 2 μl of primer R-P24GTR (2.5 μM), 0.5 μl of Rasamsonia byssochlamydoides genomic DNA (100 ng/μl), and 14.5 μl of deionized water in a total volume of 25 μl. The PCR was performed using a PTC-200 DNA engine (MJ Research, Waltham, Mass., USA) programmed for 1 cycle at 95° C. for 2 minutes; 35 cycles each at 98° C. for 10 seconds, 60° C. for 30 seconds, and 72° C. for 2.5 minutes; and 1 cycle at 72° C. for 10 minutes. The sample was then held at 12° C. until removed from the PCR machine.
The PCR product was isolated by 1.0% agarose gel electrophoresis using 40 mM Tris base, 20 mM sodium acetate, 1 mM disodium EDTA (TAE) buffer where a 1575 bp product band was excised from the gel and purified using an ILLUSTRATM GFX® PCR DNA and Gel Band Purification Kit (GE Healthcare Life Sciences, Brondby, Denmark) according to the manufacturer's instructions. The fragment was then cloned into Bam HI and Xho I digested pDau109 using an IN-FUSIONTM Cloning Kit according to the manufacturer's instructions resulting in plasmids pP24GTR and pP34RRZ. Cloning of the P24GTR and P34RRZ genes into Bam HI-Xho I digested pDau109 resulted in the transcription of the Rasamsonia byssochlamydoides P24GTR or P34RRZ gene under the control of a NA2-tpi promoter. The NA2-tpi promoter is a modified promoter from the gene encoding the Aspergillus niger neutral alpha-amylase in which the untranslated leader has been replaced by an untranslated leader from the gene encoding the Aspergillus nidulans triose phosphate isomerase.
Plasmids pP24GTR and pP34RRZ was transformed into One Shot® TOP1OF′′ Chemically Competent E. coli cells (Invitrogen, Carlsbad, Calif., USA) according to the manufacturer's protocol and plated onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubating at 37° C. overnight, colonies were observed growing under selection on the plates. Two colonies transformed with the P24GTR GH10 construct were cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid was isolated with a QIAPREP® Spin Miniprep Kit (QIAGEN Inc., Valencia, Calif., USA) according to the manufacturer's protocol.
Isolated plasmids were sequenced with vector primers and P24GTR gene specific primers in order to determine a representative plasmid expression clone that was free of PCR errors.
Example 4
Characterization of the Rasamsonia byssochiamydoides Genomic Sequences Encoding GH10 Polypeptides Having Xylanase Activity
DNA sequencing of the Rasamsonia byssochiamydoides CBS 413.71 P24GTR and asamsonia byssochiamydoides CBS 150.75 P34RRZ GH10 genomic clones was performed using an Applied Biosystems Model 3700 Automated DNA Sequencer and version 3.1 BIG-DYETM terminator chemistry (Applied Biosystems, Inc., Foster City, Calif., USA) and primer walking strategy. Nucleotide sequence data were scrutinized for quality and all sequences were compared to each other with assistance of PHRED/PHRAP software (University of Washington, Seattle, Wash., USA).
The nucleotide sequence and deduced amino acid sequence of the Rasamsonia byssochiamydoides P24GTR xylanase gene are shown in SEQ ID NO: 1 and SEQ ID NO: 2, respectively. The coding sequence is 1540 bp including the stop codon and is interrupted by four introns of 87 bp (nucleotides 63-149), 88 bp (nucleotides 304-391), 60 bp (nucleotides 525-584), and 84 bp (nucleotides 699-782). The encoded predicted protein is 406 amino acids. Using the SignalP program (Nielsen et al., 1997, Protein Engineering 10: I-6), a signal peptide of 23 residues was predicted. By sequence similarity, the xylanase was determined to comprise a carbohydrate binding module (nucleotides 1436-1537). The predicted mature protein contains 383 amino acids with a predicted molecular mass of 41 kDa and an isoelectric pH of 4.2.
The nucleotide sequence and deduced amino acid sequence of the Rasamsonia byssochiamydoides P34RRZ xylanase gene are shown in SEQ ID NO: 5 and SEQ ID NO: 6, respectively. The coding sequence is 1590 bp including the stop codon and is interrupted by four introns of 81 bp (nucleotides 63-143), 103 bp (nucleotides 298-400), 67 bp (nucleotides 534-600), and 118 bp (nucleotides 715-832). The encoded predicted protein is 406 amino acids. Using the SignalP program (Nielsen et al., 1997, Protein Engineering 10: I-6), a signal peptide of 23 residues was predicted. By sequence similarity, the xylanase was determined to comprise a carbohydrate binding module (nucleotides 1480-1587). The predicted mature protein contains 383 amino acids with a predicted molecular mass of 41 kDa and an isoelectric pH of 4.1.
A comparative pairwise global alignment of amino acid sequences was determined using the Needleman and Wunsch algorithm (Needleman and Wunsch, 1970, J. Mol. Biol. 48: 443-453) with a gap open penalty of 10, a gap extension penalty of 0.5, and the EBLOSUM62 matrix. The alignment showed that the deduced amino acid sequences of the Rasamsonia byssochiamydoides genes encoding the P24GTR and P34RRZ GH10 xylanase each share 85% identity (excluding gaps) to the deduced amino acid sequence of a predicted GH10 family protein from Rasamsonia emersonii (GENESEQP:AAU99346) with endo xylanase activity.
Example 5
Expression and Purification of the Rasamsonia byssochiamydoides GH10 Xylanase P24GTR
The expression plasmids pP24GTR and pP34RRZ were each transformed individually into protoplasts of Aspergillus oryzae MT3568 prepared according to the method of European Patent No. 0238023, pages 14-15. The transformation was performed according to the procedure described in WO 2005/042735. Aspergillus oryzae MT3568 is an amdS (acetamidase) gene disrupted derivative of JaL355 (WO 02/40694) in which pyrG auxotrophy was restored in the process of knocking out the A, oryzae amdS gene.
Transformants were purified on COVE sucrose plates through single conidia prior to sporulating them on PDA plates. Production of the Rasamsonia byssochiamydoides GH10 polypeptide by the transformants was analyzed from culture supernatants of 1 ml 96 deep well stationary cultivations at 30° C. in YP+2% glucose medium. Expression was verified by SDS-PAGE using an E-Page 8% SDS-PAGE 48 well gel (Invitrogen, Carlsbad, Calif., USA) and Coomassie blue staining. One transformant resulting from transformation wtih pP24GTR was selected for further work and designated Aspergillus oryzae 69.2. One transformant resulting from transformation wtih pP34RRZ was selected for further work and designated Aspergillus oryzae 46.4.
For larger scale production, spores of Aspergillus oryzae strains 69.2 and 46.4 were spread onto a PDA plate and incubated for five days at 37° C. The confluent spore plates were washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. The spore suspensions of each strain were then used to inoculate twenty-five 500 ml flasks each containing 100 ml of Dap-4C medium. The culture was incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broth was collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter (Thermo Fisher Scientific, Roskilde, Denmark). SDS-PAGE analysis of fresh culture broth from transformants 69.2 and 46.4 each produced a band at approximately 42 kDa. The identity of these prominent bands as the Rasamsonia byssochiamydoides GH10 polypeptides was verified by peptide sequencing.
The filtrated broth from the A. oryzae strain 69.2 cultures was adjusted to pH 7.0 and filtrated using a 0.22 μm PES filter (Nalge Nunc International, Nalgene labware cat#595-4520). Ammonium sulphate was added to the filtrate to a concentration of 1.8 M. The filtrate was loaded onto a Phenyl SepharoseTM 6 Fast Flow column (high sub) (GE Healthcare, Piscataway, N.J., USA) equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After wash with 1.0 M ammonium sulphate, the bound proteins were batch eluted with 25 mM HEPES pH 7.0. Fractions were collected and analyzed by SDS-PAGE. The fractions were pooled and applied to a SephadexTM G-25 (medium) (GE Healthcare, Piscataway, N.J., USA) column equilibrated in 25 mM HEPES pH 7.0. Fractions were collected, pooled, and applied to a SOURCETM 15Q (GE Healthcare, Piscataway, N.J., USA) column equilibrated in 25 mM HEPES pH 7.0 and bound proteins were eluted with a linear gradient from 0-1000 mM sodium chloride over 20 column volumes. Fractions were collected and analyzed by SDS-PAGE.
Example 6
Alternative Method for Producing the Rasamsonia byssochiamydoides GH10 Xylanases
Based on the nucleotide sequences identified as SEQ ID NO: 1 and SEQ ID NO: 5, synthetic genes can be obtained from a number of vendors such as Gene Art (GENEART AG BioPark, Josef-Engert-Str. 11, 93053, Regensburg, Germany) or DNA 2.0 (DNA2.0, 1430 O'Brien Drive, Suite E, Menlo Park, Calif. 94025, USA). The synthetic genes can be designed to incorporate additional DNA sequences such as restriction sites or homologous recombination regions to facilitate cloning into an expression vector.
Using the two synthetic oligonucleotide primers F-P24GTR and F-P24GTR described above, PCR can be used to amplify the full-length open reading frame from the synthetic gene of SEQ ID NO: 1 or of SEQ ID NO: 5. The gene can then be cloned into an expression vector, e.g., as described above, and expressed in a host cell, e.g., Aspergillus oryzae as described above.
Example 7
Pretreated Corn Cobs Hydrolysis Assay
Corn cobs were pretreated with NaOH (0.08 g/g dry weight cobs) at 120° C. for 60 minutes at 15% total dry weight solids (TS). The resulting material was washed with water until it was pH 8.2, resulting in washed alkaline pretreated corn cobs (APCC). Ground Sieved Alkaline Pretreated Corn Cobs (GS-APCC) was prepared by adjusting the pH of APCC to 5.0 by addition of 6 M HCl and water with extensive mixing, milling APCC in a Cosmos ICMG 40 wet multi-utility grinder (EssEmm Corporation, Tamil Nadu, India), and autoclaving for 45 minutes at 121° C., with a final TS of 3.33%. The hydrolysis of GS-APCC was conducted using 2.2 ml deep-well plates (Axygen, Union City, Calif., USA) in a total reaction volume of 1.0 ml.
The hydrolysis was performed with 10 mg of GS-APCC total solids per ml of 50 mM sodium acetate (pH 4.0 to 5.5) or 50 mM Tris (pH 6.0 to 7.0) buffer containing 1 mM manganese sulfate and various protein loadings of various enzyme compositions (expressed as mg protein per gram of cellulose). Enzyme compositions were prepared and then added simultaneously to all wells in a volume ranging from 50 μl to 200 μl, for a final volume of 1 ml in each reaction. The plate was then sealed using an ALPS-300TM plate heat sealer (Abgene, Epsom, United Kingdom), mixed thoroughly, and incubated at a specific temperature for 72 hours. All experiments reported were performed in triplicate.
Following hydrolysis, samples were filtered using a 0.45 μm MULTISCREEN® 96-well filter plate (Millipore, Bedford, Mass., USA) and filtrates were analyzed for sugar content as described below. When not used immediately, filtered aliquots were frozen at −20° C. The sugar concentrations of samples diluted in 0.005 M H2SO4 were measured using a 4.6×250 mm AMINEX® HPX-87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) by elution with 0.05% w/w benzoic acid-0.005 M H2SO4 at 65° C. at a flow rate of 0.6 ml per minute, and quantitation by integration of the glucose, cellobiose, and xylose signals from refractive index detection (CHEMSTATION®, AGILENT® 1100 HPLC, Agilent Technologies, Santa Clara, Calif., USA) calibrated by pure sugar samples. The resultant glucose equivalents were used to calculate the percentage of cellulose conversion for each reaction. The resultant xylose equivalents were used to calculate the percentage of xylo-oligosaccharide conversion for each reaction.
Glucose, cellobiose, and xylose were measured individually. Measured sugar concentrations were adjusted for the appropriate dilution factor. All HPLC data processing was performed using MICROSOFT EXCELTM software (Microsoft, Richland, Wash., USA).
The degree of xylo-oligosaccharide conversion to xylose was calculated using the following equation: % xylose conversion=xylose concentration/xylose concentration in a limit digest. In order to calculate % conversion, a 100% conversion point was set based on a cellulase control (100 mg of Trichoderma reesei cellulase supplemented with P. emersonii GH61A polypeptide (WO 2011/041397), A. fumigatus GH10 xylanase (xyn3) (WO 2006/078256), and T. emersonii GH3 beta-xylosidase (WO 2003/070956) per gram cellulose), and all values were divided by this number and then multiplied by 100. The % relative activity for each temperature was calculated using the following equation: % relative activity=(% xylose conversion of a xylanase at a certain pH and temperature−% xylose conversion of beta-xylosidase at that certain pH and temperature)/(% xylose conversion of the xylanase for the pH and temperature containing the highest % xylose conversion−% xylose conversion of beta-xylosidase for the pH and temperature containing the highest % xylose conversion)×100.
Example 8
Preparation of Talaromyces emersonii CBS 393.64 GH3 Beta-Xylosidase
A Talaromyces emersonii CBS 393.64 beta-xylosidase (GENESEQP:AZI104896) was prepared recombinantly according to Rasmussen et al., 2006, Biotechnology and Bioengineering 94: 869-876 using Aspergillus oryzae JaL355 as a host (WO 2003/070956). The filtered broth was concentrated and desalted with 50 mM sodium acetate pH 5.0 using a tangential flow concentrator equipped with a 10 kDa polyethersulfone membrane. Protein concentration was determined using a Microplate BCATM Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard.
Example 9
Preparation of Aspergillus fumigatus GH10 Xylanase (P4D6)
Aspergillus fumigatus NN055679 GH10 xylanase (xyn3) (GENESEQP:AEC74753) was prepared recombinantly according to WO 2006/078256 using Aspergillus oryzae BECh2 (WO 00/39322) as a host.
The filtered broth was desalted and buffer-exchanged into 50 mM sodium acetate pH 5.0 using a HIPREP® 26/10 Desalting Column (GE Healthcare, Piscataway, N.J., USA) according to the manufacturer's instructions. Protein concentration was determined using a Microplate BCATM Protein Assay Kit with bovine serum albumin as a protein standard.
Example 10
Effect of Rasamsonia byssochiamydoides GH10 Xylanase (P24GTR) Supplemented with Talaromyces emersonii GH3 Beta-Xylosidase Using GS-APCC at pH 4.0 to 7.0
The Rasamsonia byssochiamydoides GH10 xylanase (P24GTR) supplemented with Talaromyces emersonii GH3 beta-xylosidase (Example 8) was evaluated at 50° C., 55° C., 60° C., 65° C. from pH 4.0 to 7.0 using washed ground-sieved alkaline pretreated corn cobs (GS-APCC) as a substrate. The Aspergillus fumigatus GH10 xylanase (P4D6) supplemented with Talaromyces emersonii GH3 beta-xylosidase was also tested for comparison. The xylanases were added to the GS-APCC hydrolysis at 1 mg total protein per g cellulose supplemented with beta-xylosidase at 4.0 mg total protein per g cellulose.
The assay was performed as described in Example 7. The 1 ml reactions with GS-APCC (1% total solids) were conducted for 72 hours in 50 mM sodium acetate (pH 4.0 to 5.5) or 50 mM Tris (pH 6.0 to 7.0) buffer containing 1 mM manganese sulfate. All reactions were performed in triplicate and involved single mixing at the beginning of hydrolysis.
The results for the hydrolysis at pH 4.0 from 50° C. to 65° C. are shown in the FIGURE. The relative activity results for Rasamsonia byssochiamydoides GH10 xylanase are shown in Table 1 where the results are compared to a temperature of 65° C. and pH 4.0, and the relative activity results for Aspergillus fumigatus GH10 xylanase are shown in Table 2 where the results are compared to a temperature of 55° C. and pH 5.5. As shown in the FIGURE, the Rasamsonia byssochiamydoides GH10 xylanase supplemented with beta-xylosidase had significantly higher activity than the Aspergillus fumigatus GH10 xylanase supplemented with beta-xylosidase at all temperatures. In addition, the Rasamsonia byssochiamydoides GH10 xylanase supplemented with beta-xylosidase had increasing activity as the temperature increased from 50° C. to 65° C. while the Aspergillus fumigatus GH10 xylanase supplemented with beta-xylosidase had decreasing activity as temperature increased from 50° C. to 65° C. As shown in Table 1, the Rasamsonia byssochiamydoides GH10 xylanase had an optimal temperature of 65° C. and an optimal pH range (greater than 75% relative activity) from pH 4.0 to 6.0 at the optimal temperature. In comparison, the Aspergillus fumigatus GH10 xylanase had an optimal temperature of 55° C. and an optimal pH range (greater than 75% relative activity) from pH 4.5 to 6.0 at 55° C. Overall, the Rasamsonia byssochiamydoides GH10 xylanase had a higher optimal temperature activity and activity at lower pH than the Aspergillus fumigatus GH10 xylanase.













TABLE 1






pH 4.0
pH 4.5
pH 5.0
pH 5.5
pH 6.0
pH 7.0



% Relative
% Relative
% Relative
% Relative
% Relative
% Relative


Sample
Activity
Activity
Activity
Activity
Activity
Activity







R. byssochlamydoides
80%
79%
73%
66%
62%
40%


GH10 xyn (50° C.)








(P24GTR)








R. byssochlamydoides
83%
81%
77%
72%
68%
34%


GH10 xyn (55° C.)








(P24GTR)








R. byssochlamydoides
93%
87%
81%
71%
75%
27%


GH10 xyn (60° C.)








(P24GTR)








R. byssochlamydoides
100%
95%
88%
76%
83%
21%


GH10 xyn (65° C.)








(P24GTR)






















TABLE 2






pH 4.0
pH 4.5
pH 5.0
pH 5.5
pH 6.0
pH 7.0



% Relative
% Relative
% Relative
% Relative
% Relative
% Relative


Sample
Activity
Activity
Activity
Activity
Activity
Activity







A. fumigatus GH10
73%
92%
96%
94%
91%
69%


xyn3 (50° C.)








A. fumigatus GH10
64%
90%
96%
100%
96%
54%


xyn3 (55° C.)








A. fumigatus GH10
56%
79%
98%
98%
93%
34%


xyn3 (60° C.)








A. fumigatus GH10
54%
70%
87%
89%
87%
20%


xyn3 (65° C.)















Example 11
Specific Activity of Rasamsonia byssochiamydoides GH10 Xylanase and Aspergillus fumigatus GH10 Xylanase on Birchwood Xylan at pH 5.0, 50° C.
The specific activities of the Rasamsonia byssochiamydoides GH10 xylanase (P24GTR) and Aspergillus fumigatus GH10 xylanase were determined on birchwood xylan (Sigma Chemical Co., Inc., St. Louis, Mo., USA). A solution of birchwood xylan at 2 g per liter was prepared in 50 mM sodium acetate buffer, pH 5.0. Ten μl of xylanase was added to 190 μl of the 2 g/L of birchwood xylan at different enzyme loadings. Substrate alone and enzyme alone controls were also run. The reactions were incubated at 50° C. for 30 minutes and then stopped by adding 50 μl of 0.5 M NaOH to each reaction. The reducing sugars produced were determined using a para-hydroxybenzoic acid hydrazide (PHBAH, Sigma, St. Louis, Mo., USA) assay adapted to a 96 well microplate format as described below. Briefly, a 100 μl aliquot of an appropriately diluted sample was placed in a 96-well conical bottomed microplate. Reactions were initiated by adding 50 μl of 1.5% (w/v) PHBAH in 2% NaOH to each well. Plates were heated uncovered at 95° C. for 10 minutes. Plates were allowed to cool to room temperature and 50 μl of Milli Q H2O (Millipore, Bedford, Mass., USA) were added to each well. A 100 μl aliquot from each well was transferred to a flat bottomed 96 well plate and the absorbance at 410 nm was measured using a SpectraMax Microplate Reader (Molecular Devices, Sunnyvale, Calif.). Glucose standards (0.1-0.0125 mg/ml diluted with 0.4% sodium hydroxide) were used to prepare a standard curve to translate the obtained A410nm values into glucose equivalents. The enzyme loading versus the reducing sugars produced was plotted and the linear range was used to calculate the specific activity of Rasamsonia byssochiamydoides GH10 xylanase and Aspergillus fumigatus GH10 xylanase, as expressed as pmole glucose equivalent produced per minute per mg enzyme, or IU/mg. The specific activity results are shown in Table 3.







TABLE 3







Specific activity on birchwood xylan at pH 5.0, 50° C.











Specific activity on birchwood



Enzyme
xylan, IU/mg







Rasamsonia byssochlamydoides
111.6 +/− 8.6  



GH10 xylanase (P24GTR)




Aspergillus fumigatus GH10
 16 +/− 4.2



xylanase










Example 12
Preparation of Rasamsonia emersonii GH10 Xylanase (P23CQ3)
Rasamsonia emersonii GH10 xylanase (GENESEQP:AZ105030) was prepared recombinantly and purified according to WO 2011/057140 using Aspergillus oryzae (WO 00/39322) as a host. Protein concentration was determined using a Microplate BCATM Protein Assay Kit with bovine serum albumin as a protein standard.
Example 13
Specific Activity of Rasamsonia byssochiamydoides GH10 Xylanase and Rasamsonia emersonii GH10 Xylanase on Birchwood Xylan at pH 4.0, 60° C.
The specific activities of the Rasamsonia byssochiamydoides GH10 xylanase (P24GTR) and Rasamsonia emersonii GH10 xylanase were determined on birchwood xylan (Sigma Chemical Co., Inc.) as described in Example 11. The solution of birchwood xylan at 2 g per liter was prepared in 50 mM sodium acetate buffer, pH 4.0, and reactions were incubated at 60° C. for 30 minutes. Xylose standards (0.1-0.0125 mg/ml diluted with 0.4% sodium hydroxide) were used to prepare a standard curve to translate the obtained A410nm values into xylose equivalents. The specific activity results are shown in Table 4.







TABLE 4







Specific activity on birchwood xylan at pH 4.0, 60° C.











Specific activity on birchwood



Enzyme
xylan, IU/mg (pH 4.0, 60° C.)







Rasamsonia byssochlamydoides
  652 +/− 107.3



GH10 xylanase (P24GTR)




Rasamsonia emersonii GH10
317.8 +/− 58.9 



xylanase (P23CQ3)










Example 14
Preparation of the Natural Variant Rasamsonia byssochiamydoides GH10 Xylanase P34RRZ
The protein broth of Rasamsonia byssochiamydoides GH10 xylanase P34RRZ was desalted and buffer exchanged in 50 mM sodium acetate pH 5.0 using an ECONO-PACO 10-DG desalting column (Bio-Rad Laboratories, Inc.) according to the manufacturer's instructions. Protein concentration was determined using a Microplate BCATM Protein Assay Kit in which bovine serum albumin was used as a protein standard.
Example 15
Specific Activity of the Natural Variant Rasamsonia Byssochiamydoides GH10 Xylanase P34RRZ on Birchwood Xylan at pH 4.0, 60° C.
The specific activity of the natural variant Rasamsonia byssochiamydoides GH10 xylanase (P34RRZ) was determined on birchwood xylan (Sigma Chemical Co., Inc.) as described in Example 13. The specific activity results are shown in Table 5.







TABLE 5







Specific activity on birchwood xylan at pH 4.0, 60° C.











Specific activity on birchwood



Enzyme
xylan, IU/mg (pH 4.0, 60° C.)







Rasamsonia byssochlamydoides
578.2 +/− 98.7



GH10 xylanase (P34RRZ)











The present invention is further described by the following numbered paragraphs:
[1] An isolated polypeptide having xylanase activity, selected from the group consisting of:
(a) a polypeptide having at least 90% sequence identity to the mature polypeptide of SEQ ID NO: 2 or SEQ ID NO: 6;
(b) a polypeptide encoded by a polynucleotide having at least 90% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1 or the cDNA sequence thereof, or to the mature polypeptide coding sequence of SEQ ID NO: 5 or the cDNA sequence thereof;
(c) a variant of the mature polypeptide of SEQ ID NO: 2 or of the mature polypeptide of SEQ ID NO: 4 comprising a substitution, deletion, and/or insertion at one or more positions; and
(d) a fragment of the polypeptide of (a), (b), or (c), that has xylanase activity.
[2] The polypeptide of paragraph [1], having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide of SEQ ID NO: 2.
[3] The polypeptide of paragraph [1] or [2], having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide of SEQ ID NO: 6.
[4] The polypeptide of any of paragraphs [1]-[3], which is encoded by a polynucleotide having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1 or the cDNA sequence thereof.
[5] The polypeptide of any of paragraphs [1]-[4], which is encoded by a polynucleotide having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 5 or the cDNA sequence thereof.
[6] The polypeptide of any of paragraphs [1]-[5], comprising or consisting of SEQ ID NO: 2 or the mature polypeptide thereof.
[7] The polypeptide of paragraph [6], wherein the mature polypeptide is amino acids 24 to 406 of SEQ ID NO: 2.
[8] The polypeptide of any of paragraphs [1]-[5], comprising or consisting of SEQ ID NO: 6, or the mature polypeptide thereof.
[9] The polypeptide of paragraph [8], wherein the mature polypeptide is amino acids 24 to 406 of SEQ ID NO: 6.
[10] The polypeptide of any of paragraphs [1]-[5], which is a variant of the mature polypeptide of SEQ ID NO: 2, or of the mature polypeptide of SEQ ID NO: 6, comprising a substitution, deletion, and/or insertion at one or more positions.
[11] The polypeptide of paragraph [1], which is a fragment of SEQ ID NO: 2 or a fragment of SEQ ID NO: 6, wherein the fragment has xylanase activity.
[12] The polypeptide of any of paragraphs [1]-[11], which is encoded by the polynucleotide contained in Rasamsonia byssochlamydoides CBS 413.71.
[13] The polypeptide of any of paragraphs [1]-[12], which has at least 10%, e.g., at least 15% and at least 20%, more xylanase activity at pH 4.0 and 60° C. or 65° C. than at pH 4.0 and 50° C.
[14] The polypeptide of any of paragraphs [1]-[13], which has at least 10%, e.g., at least 15% and at least 20%, more xylanase activity at pH 4.0 and 50° C., 55° C., 60° C., or 65° C. than at pH 6.0 and 50° C., 55° C., 60° C., or 65° C., respectively.
[15] An isolated polypeptide having xylanase activity, which has at least 10%, e.g., at least 15% and at least 20%, more xylanase activity at pH 4.0 and 60° C. or 65° C. than at pH 4.0 and 50° C.
[16] An isolated polypeptide having xylanase activity, which has at least 10%, e.g., at least 15% and at least 20%, more xylanase activity at pH 4.0 and 50° C., 55° C., 60° C., or 65° C. than at pH 6.0 and 50° C., 55° C., 60° C., or 65° C., respectively.
[17] An isolated polypeptide comprising a catalytic domain selected from the group consisting of:
(a) a catalytic domain having at least 60% sequence identity to amino acids 24 to 340 of SEQ ID NO: 2, or having at least 60% sequence identity to amino acids 24 to 341 of SEQ ID NO: 6;
(b) a catalytic domain encoded by a polynucleotide having at least 90% sequence identity to nucleotides 157 to 1339 of SEQ ID NO: 1 or the cDNA sequence thereof, or having at least 90% sequence identity to nucleotides 151 to 1387 of SEQ ID NO: 5 or the cDNA sequence thereof;
(c) a variant of amino acids 24 to 340 of SEQ ID NO: 2, or of amino acids 24 to 341 of SEQ ID NO: 6, comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions; and
(d) a fragment of the catalytic domain of (a), (b), or (c) that has xylanase activity.
[18] The polypeptide of paragraph [17], further comprising a carbohydrate binding module.
[19] An isolated polypeptide comprising a carbohydrate binding module operably linked to a catalytic domain, wherein the binding domain is selected from the group consisting of:
(a) a carbohydrate binding module having at least 90% sequence identity to amino acids 373 to 406 of SEQ ID NO: 2 or having at least 90% sequence identity to amino acids 371 to 406 of SEQ ID NO: 6;
(b) a carbohydrate binding module encoded by a polynucleotide having at least 90% sequence identity to nucleotides 1436 to 1537 of SEQ ID NO: 1 or the cDNA sequence thereof, or by a polynucleotide having at least 90% sequence identity to nucleotides 1480 to 1587 of SEQ ID NO: 5 or the cDNA sequence thereof;
(c) a variant of amino acids 373 to 406 of SEQ ID NO: 2, or of amino acids 3731 to 406 of SEQ ID NO: 6, comprising a substitution, deletion, and/or insertion at one or more (e.g., several) positions; and

    
    
        (d) a fragment of the carbohydrate binding module of (a), (b), or (c) that has binding activity.
    
    


[20] The polypeptide of paragraph [19], wherein the catalytic domain is obtained from a hydrolase, isomerase, ligase, lyase, oxidoreductase, or transferase, e.g., an aminopeptidase, amylase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, alpha-galactosidase, beta-galactosidase, glucoamylase, alpha-glucosidase, beta-glucosidase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, xylanase, or beta-xylosidase.
[21] A composition comprising the polypeptide of any of paragraphs [1]-[20].
[22] An isolated polynucleotide encoding the polypeptide of any of paragraphs [1]-[20].
[23] A nucleic acid construct or expression vector comprising the polynucleotide of paragraph [22] operably linked to one or more control sequences that direct the production of the polypeptide in an expression host.
[24] A recombinant host cell comprising the polynucleotide of paragraph [22] operably linked to one or more control sequences that direct the production of the polypeptide.
[25] A method of producing the polypeptide of any of paragraphs [1]-[20], comprising: cultivating a cell, which in its wild-type form produces the polypeptide, under conditions conducive for production of the polypeptide.
[26] The method of paragraph [25], further comprising recovering the polypeptide.
[27] A method of producing a polypeptide having xylanase activity, comprising: cultivating the host cell of paragraph [24] under conditions conducive for production of the polypeptide.
[28] The method of paragraph [27], further comprising recovering the polypeptide.
[29] A transgenic plant, plant part or plant cell transformed with a polynucleotide encoding the polypeptide of any of paragraphs [1]-[20].
[30] A method of producing a polypeptide having xylanase activity, comprising: cultivating the transgenic plant or plant cell of paragraph [29] under conditions conducive for production of the polypeptide.
[31] The method of paragraph [30], further comprising recovering the polypeptide.
[32] A method of producing a mutant of a parent cell, comprising inactivating a polynucleotide encoding the polypeptide of any of paragraphs [1]-[20], which results in the mutant producing less of the polypeptide than the parent cell.
[33] A mutant cell produced by the method of paragraph [32].
[34] The mutant cell of paragraph [33], further comprising a gene encoding a native or heterologous protein.
[35] A method of producing a protein, comprising: cultivating the mutant cell of paragraph [33] or [34] under conditions conducive for production of the protein.
[36] The method of paragraph [35], further comprising recovering the protein.
[37] A double-stranded inhibitory RNA (dsRNA) molecule comprising a subsequence of the polynucleotide of paragraph [22], wherein optionally the dsRNA is an siRNA or an miRNA molecule.
[38] The double-stranded inhibitory RNA (dsRNA) molecule of paragraph [37], which is about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more duplex nucleotides in length.
[39] A method of inhibiting the expression of a polypeptide having xylanase activity in a cell, comprising administering to the cell or expressing in the cell the double-stranded inhibitory RNA (dsRNA) molecule of paragraph [37] or [38].
[40] A cell produced by the method of paragraph [39].
[41] The cell of paragraph [40], further comprising a gene encoding a native or heterologous protein.
[42] A method of producing a protein, comprising: cultivating the cell of paragraph [40] or [41] under conditions conducive for production of the protein.
[43] The method of paragraph [42], further comprising recovering the protein.
[44] An isolated polynucleotide encoding a signal peptide comprising or consisting of amino acids 1 to 23 of SEQ ID NO: 2 or of amino acids 1 to 23 of SEQ ID NO: 6.
[45] A nucleic acid construct or expression vector comprising a gene encoding a protein operably linked to the polynucleotide of paragraph [44], wherein the gene is foreign to the polynucleotide encoding the signal peptide.
[46] A recombinant host cell comprising a gene encoding a protein operably linked to the polynucleotide of paragraph [44], wherein the gene is foreign to the polynucleotide encoding the signal peptide.
[47] A method of producing a protein, comprising: cultivating a recombinant host cell comprising a gene encoding a protein operably linked to the polynucleotide of paragraph [40], wherein the gene is foreign to the polynucleotide encoding the signal peptide, under conditions conducive for production of the protein.
[48] The method of paragraph [47], further comprising recovering the protein.
[49] A process for degrading a cellulosic or xylan-containing material, comprising: treating the cellulosic or xylan-containing material with an enzyme composition in the presence of the polypeptide having xylanase activity of any of paragraphs [1]-[20].
[50] The process of paragraph [49], wherein the cellulosic or xylan-containing material is pretreated.
[51] The process of paragraph [49] or [50], wherein the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a polypeptide having cellulolytic enhancing activity, a hemicellulase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[52] The process of paragraph [51], wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[53] The process of paragraph [51], wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
[54] The process of any of paragraphs [49]-[53], further comprising recovering the degraded cellulosic or xylan-containing material.
[55] The process of paragraph [54], wherein the degraded cellulosic or xylan-containing material is a sugar.
[56] The process of paragraph [55], wherein the sugar is selected from the group consisting of glucose, xylose, mannose, galactose, and arabinose.
[57] A process for producing a fermentation product, comprising:
(a) saccharifying a cellulosic or xylan-containing material with an enzyme composition in the presence of the polypeptide having xylanase activity of any of paragraphs [1-16];
(b) fermenting the saccharified cellulosic or xylan-containing material with one or more fermenting microorganisms to produce the fermentation product; and
(c) recovering the fermentation product from the fermentation.
[58] The process of paragraph [57], wherein the cellulosic or xylan-containing material is pretreated.
[59] The process of paragraph [57] or [58], wherein the enzyme composition comprises the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a polypeptide having cellulolytic enhancing activity, a hemicellulase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[60] The process of paragraph [59], wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[61] The process of paragraph [59] or [60], wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
[62] The process of any of paragraphs [57]-[61], wherein steps (a) and (b) are performed simultaneously in a simultaneous saccharification and fermentation.
[63] The process of any of paragraphs [57]-[62], wherein the fermentation product is an alcohol, an alkane, a cycloalkane, an alkene, an amino acid, a gas, isoprene, a ketone, an organic acid, or polyketide.
[64] A process of fermenting a cellulosic or xylan-containing material, comprising:
fermenting the cellulosic or xylan-containing material with one or more fermenting microorganisms, wherein the cellulosic or xylan-containing material is saccharified with an enzyme composition in the presence of the polypeptide having xylanase activity of any of paragraphs [1]-[20].
[65] The process of paragraph [64], wherein the fermenting of the cellulosic or xylan-containing material produces a fermentation product.
[66] The process of paragraph [65], further comprising recovering the fermentation product from the fermentation.
[67] The process of any of paragraphs [64]-[66], wherein the cellulosic or xylan-containing material is pretreated before saccharification.
[68] The process of any of paragraphs [64]-[67], wherein the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a polypeptide having cellulolytic enhancing activity, a hemicellulase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[69] The process of paragraph [68], wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[70] The process of paragraph [68], wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
[71] The process of any of paragraphs [65]-[70], wherein the fermentation product is an alcohol, an alkane, a cycloalkane, an alkene, an amino acid, a gas, isoprene, a ketone, an organic acid, or polyketide.
[72] A whole broth formulation or cell culture composition comprising the polypeptide of any of paragraphs [1]-[20].
[73] An enzyme composition comprising the polypeptide having xylanase activity of any of paragraphs [1]-[20] and one or more enzymes selected from the group consisting of a cellulase, a polypeptide having cellulolytic enhancing activity, a hemicellulase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[74] The enzyme composition of paragraph [73], wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[75] The enzyme composition of paragraph [73] or [74], wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
The invention described and claimed herein is not to be limited in scope by the specific aspects herein disclosed, since these aspects are intended as illustrations of several aspects of the invention. Any equivalent aspects are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. In the case of conflict, the present disclosure including definitions will control.

## Claims

1. An isolated recombinant host cell transformed with a nucleic acid construct comprising a polynucleotide encoding a polypeptide having xylanase activity, wherein the polynucleotide is operably linked to one or more control sequences that direct the production of the polypeptide, and wherein the polypeptide having xylanase activity has at least 99% sequence identity to amino acids 24 to 406 of SEQ ID NO: 6, wherein the polypeptide is heterologous to the host cell.

2. The recombinant host cell of claim 1, wherein the polypeptide having xylanase activity comprises (i) the polypeptide of SEQ ID NO: 6; or (ii) amino acids 24 to 406 of the polypeptide of SEQ ID NO: 6.

3. The recombinant host cell of claim 1, wherein the polypeptide having xylanase activity is encoded by (i) a polynucleotide comprising SEQ ID NO: 5, (ii) a polynucleotide comprising nucleotides 157 to 1537 of the polynucleotide of SEQ ID NO: 5, or (iii) the cDNA of (i) or (ii).

4. The recombinant host cell of claim 1, wherein one or more of the control sequences is heterologous to the polynucleotide encoding the polypeptide having xylanase activity.

5. A method of producing a polypeptide having xylanase activity, comprising cultivating the recombinant host cell of claim 1 under conditions conducive for production of the polypeptide.

6. A nucleic acid construct comprising a polynucleotide encoding a polypeptide having xylanase activity, wherein the polynucleotide is operably linked to one or more heterologous control sequences that direct the production of the polypeptide, and wherein the polypeptide having xylanase activity has at least 99% sequence identity to amino acids 24 to 406 of SEQ ID NO: 6, wherein the polypeptide is heterologous to the host cell.

7. The nucleic acid construct of claim 6, wherein the polypeptide having xylanase activity comprises (i) the polypeptide of SEQ ID NO: 6; or (ii) amino acids 24 to 406 of the polypeptide of SEQ ID NO: 6.

8. A method of producing a polypeptide having xylanase activity, comprising cultivating a recombinant host cell transformed with the nucleic acid construct of claim 6 under conditions conducive for production of the polypeptide.

9. A recombinant host cell transformed with the nucleic acid construct of claim 6.