bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipopolysaccharide,LPSremoval, Depyrogenation
Authors: Magalhães Pérola O. , Pessoa Adalberto
Published: April 2010

Advances in biotechnology have opened up numerous possibilities for the large‐scale production of many biomolecules that are important for research, pharmaceuticals, and industrial applications. The development of techniques and methods for the separation and purification of proteins and other biomolecules has been of paramount importance for many of these advances in the biotechnology industry. Such biomolecules may be expressed as soluble extracellular form, soluble intracellular form, or as membrane constitute or inclusion bodies. In all three cases, use of cellular rupture procedures for the recovery of the biomolecules of interest, which lead to the release of a large quantity of lipopolysaccharide (LPS)‐type endotoxins, is necessary. The presence of small amounts of endotoxin in recombinant protein preparations can cause side effects such as endotoxin shock, tissue injury, and even death in host organism. Owing to these reactions, research on the methods used to remove endotoxins from drugs, injectables, and other biological and pharmaceutical products is necessary. Taking into consideration the main techniques used as well as the state of the art of the technology in this field, the techniques of endotoxin determination and interaction of endotoxins with proteins are presented.
L
‐Malic Acid Production by Fumarase
Authors: Yonghong Hu , Pingkai Ouyang
Published: April 2010

Malic acid is an intermediate metabolite in the tricarboxylic acid cycle. It is widely used in pharmaceutical, food processing, and other industries. Malic acid was produced commercially by chemical synthesis or through fermentation processes that convert fumaric acid to
L
‐malic acid by using fumarase. In this article, we introduce several methods to produce
L
‐malic acid by fumarase.
Brevibacterium ammoniagenes
MA‐2 and
Brevibacterium flavum
MA‐3 were selected for producing fumarase. The fermentation results of these two strains showed that the internal‐loop airlift reactor was more suitable than the stirred reactor. In addition, a comparison of cell collection methods showed that flocculation and coagulation were more suitable. We also established several methods of cell immobilization using mixed gels, which were better than the conventional single κ‐Carrageenan entrapment. When the immobilized cells of
B. ammoniagenes
MA‐2 and
B. flavum
MA‐3 catalyzed the ammonia fumarate to
L
‐malic acid, the product concentrations were 210 g/L and 218 g/L respectively. Furthermore, the apparent kinetic parameters and the intrinsic kinetic parameters of immobilized cells were obtained. In order to cut down the residual fumaric acid, a conversion system was established to produce
L
‐malate coupling with immobilized
Escherichia coli
No. 1 cells for converting the remnant fumarate to
L
‐aspartic acid. A system‐integrated reaction and separation process, which produced
L
‐malic acid from free cells containing fumarase, was established. The yield was up to 99.9% under the optimum reaction conditions, giving us a satisfactory and economical result for industrial application. Finally, the mechanism for the system‐integrated reaction and separation process was studied.
Mammalian Cell Bioreactors
Authors: Zhou Weichang , Seth Gargi , Guardia Maria J. , Hu Wei‐Shou
Published: April 2010

Mammalian cells are widely used in the production of viral vaccines and therapeutic proteins. Most of those processes employ cells growing in suspension; however, some, especially those in vaccine production, use adherent cells. Stirred‐tank bioreactors are most widely used for mammalian cell culture processes. When a stirred‐tank bioreactor is used for growing adherent cells, a supporting surface for cell attachment is provided by the use of microcarriers or macroporous microcarriers. Alternatively, adherent cells are grown as aggregates in suspension. Fed‐batch culture is commonly practised since it reaches high cell and product concentrations. When a stirred‐tank bioreactor is operated in a continuous mode, it is a common practice to employ a cell retention device for perfusion in order to increase cell and product concentrations. As mammalian cell culture processes are increasingly being used in the manufacturing, one also witnesses an increasing adoption of disposable (or single‐use) cell culture devices. Traditional roller bottles are still often seen. Additionally, multiple flat plates or parallel trays, along with bag type cell growth chambers and even plastic stirred tanks, are used in moderate‐scale production and in the seed culture propagation for large‐scale bioreactors. Those disposable devices offer simplicity in operations and ease process validation in the production of biopharmaceuticals. Recently, some innovative bioreactors developed nearly two decades ago are finding applications in tissue engineering. Furthermore, the demand for high throughput operations in cell culture processing will continue to drive the innovations in bioreactor technology.
Cell Viability, Measurement
Authors: Wei Ning , Sommer Benjamin
Published: April 2010

Cell viability is one of the fundamental interests in biological research and applications. It relates to the productivity, quality as well as the performance of various biological systems. Major approaches to assessment of cell viability fall into the following categories: permeability assays, functional assays, flow cytometry, and physical methods.
Membrane Chromatography
Authors: Pieracci John , Thömmes Jörg
Published: April 2010

It has been nearly 20 years since membrane chromatography was first introduced as a technology capable of purifying proteins. In that time, a large body of work has been generated which has described the fundamental transport mechanisms behind membrane adsorption, the advantages that membrane adsorbers possess as compared to column chromatography, the various membrane surface chemistries that can be created, and the application of membrane chromatography in the purification of a wide variety of proteins. In this review, the basic concept of membrane chromatography is explained, which includes a discussion of the factors that control membrane performance and how that performance can be optimized. The diverse ligand chemistries that have been used to create the three main families of membrane adsorbers that is affinity, hydrophobic interaction, and ion exchange, are described along with available membrane adsorber formats. Finally, applications of membrane adsorbers throughout a standard protein purification train, from the direct capture of proteins from unclarified feedstocks to the clearance of trace impurities in final polishing steps, will be demonstrated using small‐ and pilot‐scale examples.
Methanotrophs
Authors: Smith Thomas J. , Murrell J. Colin
Published: April 2010

Methanotrophic bacteria have the unique ability to grow using methane as their sole source of carbon and energy. Methane monooxygenases (MMOs), which are the enzymes that catalyze the difficult reaction of methane with molecular oxygen, have the potential for upgrading of methane to the more valuable fuel methanol. MMOs, especially the catalytically versatile soluble MMO, can cooxidize a wide range of hydrocarbons and chlorinated hydrocarbons (including trichloroethylene) and much progress has been made toward their development as commercial catalysts for synthetic organic chemistry and bioremediation. The ability of methanotrophs to synthesize all organic cellular components from the simple hydrocarbon methane has led to a commercial process for making single‐cell protein (SCP) from methane. There have also been major developments toward their use as hosts for inexpensive production of recombinant proteins and valuable small molecules. Recent isolation of novel groups of methanotrophs has revealed a previously unknown diversity in their taxonomic origin and ability to thrive under extreme environmental conditions. We predict that genomic and postgenomic analysis of diverse methanotrophs and their enzymes will lead to new possibilities in biotechnology.
Methylotrophs, Industrial Applications
Authors: Leak David J.
Published: April 2010

Early investigations into the potential applications of methylotrophs focused mainly on the use of methane and methanol as cheap feedstocks for the production of single cell protein, and until recently this possibility was still being investigated. Despite the decline of this initial interest, the spin‐offs in terms of fundamental biochemical and genetic information, fermentation systems, and bioreactor design have opened up other avenues, either for products where substrate costs are paramount (e.g. amino acids), products originating from some of the unique features of C1metabolism (e.g. enzymes) or fortuitous discoveries (e.g. thePichia pastorisexpression system). After considering fundamental aspects of metabolism and energetics of methylotrophs and their implications for product formation, this review follows these subdivisions in turn, endeavoring to assess their future potential.
Microbial Growth Measurement
Authors: Koch Arthur L.
Published: April 2010

This paper outlines the physical techniques used to follow growth of bacteria and measure their amounts.
Microcarrier Culture
Authors: Sharfstein Susan T. , Kaisermayer Christian
Published: April 2010

Microcarrier culture provides an easily scalable approach to culture of anchorage‐dependent mammalian cells, providing a much higher surface area‐to‐volume ratio compared with roller bottles or flat layer cultivation systems. Microcarriers are also useful for the production of recombinant proteins, particularly to facilitate cell retention in cases where perfusion would be advantageous, for example, low specific productivity or unstable products. Microcarriers provide the cultivation surface that is necessary for adherent cells, and macroporous carriers can be used to immobilize suspension cells. In this review of microcarrier culture, we discuss the history of microcarrier use, strategies for optimal development of microcarrier‐based processes, the use of microcarriers for viral vaccine and recombinant protein production, and new biomedical applications for microcarriers, including tissue engineering, stem‐cell culture, andin vitrotoxicology.
Micropropagation of Plants
Authors: Loberant Beth , Altman Arie
Published: April 2010

Micropropagation (or in vitro propagation) is the most common term used for clonal, true‐to‐type propagation of plants by a variety of tissue, cell and organ culture methods. It implies the aseptic culture of small sections (i.e., explants) of tissues and organs, in closed vessels with defined culture media and under controlled environmental conditions. Micropropagation, in addition to genetic engineering, is at present the most commercially efficient and practically‐oriented plant biotechnology, resulting in rapid generation of a large number of clonal plants of many plant species, which are in many cases also virus‐ or other pathogen‐free. It is now the technical link in the generation of transgenic plants and somatically‐bred plants.

Following a brief history and a presentation of the objectives of micropropagation and related applications, we discuss the basic biological principles of micropropagation, including totipotency of plant cells, cell division and callus formation, and the major forms of differentiation and regeneration (axillary bud proliferation, organogenesis, and somatic embryogenesis). The practice of micropropagation is dependent on precise implementation of several technical aspects and developmental/growth stages, including the use of proper explants, asepsis (axenic culture), culture media composition and use of appropriate growth vessels, and the monitoring and control of macro‐ and micro‐environmental conditions within the laboratory and acclimatization facility. We include a review of the design and maintenance of the laboratory and further discuss the advantages and disadvantages of micropropagation and the organizational, economic and financial aspects of commercial micropropagation. In addition, we address critical limiting factors such as recalcitrance, somatic variation and trueness‐to‐type, and contamination. New trends in improving the efficiency of micropropagation conclude this chapter.
Monoclonal Antibody Production, Cell Lines
Authors: Markusen Julia F. , Robinson David K.
Published: April 2010

Production of recombinant antibodies begins with construction of the cell line that will be used for expression of the final monoclonal antibody (MAb) product. There are many steps downstream of cell line construction for ensuring safety, efficacy, quality, productivity, and regulatory acceptability; however, consideration of these attributes at the point of cell line selection is critical. Each of these important features can be greatly influenced by the choice of the host system. The product quality attribute most likely to be influenced by the cell line chosen for manufacture of a MAb is glycosylation. Rather than producing a highly homogeneous oligosaccharide structure, most host cell lines produce antibody with an array of different oligosaccharide structures. In addition, these structures may contain immunogenic, nonhuman forms potentially affecting the safety and efficacy of the product. All of the MAbs currently licensed in the United States are produced in two mammalian cell lines, hamster or murine. Mammalian cell line expression vectors and selection methods have been optimized to generate highly productive systems. To date, there are no approved therapeutic MAbs in the United States that are produced in human, fungal, bacterial or transgenic systems. However, advances in genetic engineering of these host cell systems to control oligosaccharide structures and regulatory acceptance for production of other therapeutic proteins in these alternative host platforms warrant consideration of these systems for future MAb production.
Oils, Microbial Production
Authors: Sakuradani Eiji , Ogawa Jun , Kishino Shigenobu , Ando Akinori , Yokozeki Kenzo , Shimizu Sakayu
Published: April 2010

The term single cell oils is used for unique oils produced by microorganisms. Many attempts have been made to produce useful fatty acids or oils containing them by microbial processes. One example is the production of cocoa‐butter equivalent oil by yeast which abundantly produces stearic acid. The most successful example occurs in the production of oils containing polyunsaturated fatty acids (PUFAs) having more than one double bond. Here, microbial PUFA production is discussed mainly as a typical example of single cell oils. Furthermore, the examples of PUFA transformation by microorganisms to conjugated fatty acids and so on are also introduced.
Organosilicon Compounds, Enzymatic Modification
Authors: Zong Min‐Hua , Tanaka Atsuo , Kawamoto Takuo
Published: April 2010

Organosilicon compounds play important roles in organic chemistry and pharmaceutical applications. Therefore, increasing attention has been focused on the preparation of organosilicon compounds with desired chemical and physical properties by the effective biocatalysts. This article outlines the bioconversion of organosilicon compounds by the use of biocatalysts such as microorganisms, alcohol dehydrogenases, hydrolases, and hydroxynitrile lyases. The preparation of silicon‐containing amino acids and cyanohydrins by the bioconversion is also described. Furthermore, the effects of silicon atom on the enzymatic reaction are discussed with comparative studies by using organosilicon compounds and corresponding carbon compounds as substrates of enzymes.
Osmolarity Effects, Chinese Hamster Ovary Cell Culture
Authors: Min Lee Gyun , Koo Jone
Published: April 2010

Medium osmolality is an important factor to consider during recombinant Chinese hamster ovary (rCHO) cell culture. Several studies have shown that hyperosmolality improves the specific foreign protein productivity (q), although the effect of hyperosmolality onqin rCHO cell culture seems to differ between cell lines, clones, and gene dosages. However, hyperosmolality decreases the specific growth rate (μ). The depressed cell growth that occurs at elevated osmolality generates a dilemma in that althoughqis enhanced, a substantial increase in the maximum foreign protein concentration is not attainable. As a remedy to this problem, the addition of osmoprotective compounds, such as glycine betaine, or the regulation of anti‐apoptotic proteins, are offered as potential methods to alleviate the depressed growth and, thus, increase the foreign protein production during hyperosmotic culture.
Phenylalanine Dehydrogenase
Authors: Asano Yasuhisa
Published: April 2010

NAD + ‐dependent phenylalanine dehydrogenase (PheDH) was first found to occur in 1984, followed by a number of studies on its enzymological properties, structure, reaction mechanisms, applications to the synthesis ofL‐amino acids from their α‐keto analogs and the microdetermination of Phe and its keto analog.
Photobioreactors
Authors: Tredici Mario R. , Chini Zittelli Graziella , Rodolfi Liliana
Published: April 2010

Industrial production of microalgae is prevalently carried out in raceway ponds. However, there is the diffused perception that open systems have reached their technological limit and that closed photobioreactors (PBR) will prevail in the future even at a very large scale. PBR are flexible systems that can be optimized according to the characteristics of the cultivated species and permit to cultivate microalgae that cannot be grown in open ponds because of contamination. In the last decades PBR have much evolved and plenty of new designs have been proposed. This review focuses on those systems used outdoors at the pilot level and on a commercial scale. The main design criteria for PBR (construction materials, surface‐to‐volume ratio, orientation and inclination, mixing and mass transfer, and temperature control) are outlined, and the principal PBR categories (tubular and flat, horizontal, inclined, vertical and spiral; manifold and serpentine) are illustrated, with examples of commercial plants that have been closed down and are currently in operation. The performance in ponds and PBR is also compared and the issue of productivity evaluation is discussed.
Pichia, Optimization of Protein Expression
Authors: Sreekrishna Koti
Published: April 2010

Pichia pastorisis a methylotrophic yeast. It is able to use methanol as sole carbon source for energy as well as for growth. It was originally developed by Phillips Petroleum Company (Bartlesville, OK) as an organism of choice for bioconversion of natural gas (methane) into food (single cell protein). With the advent of cloning of its highly regulated alcohol oxidase (AOX1) promoter, availability of auxotrophicPichiastrain [GS115 (his4)], andPichiatransformation protocols, the successful high level expression of several proteins has been readily demonstrated. The purpose of this article is to highlight the strategies that have been used for optimal protein expression with thePichiayeast expression system, which in the past few years has turned out to be a versatile and impressive yeast for the production of proteins.
Plant Cell Culture, Laboratory Techniques
Authors: Fowler Mark Richard
Published: April 2010

Plant cell cultures providepowerful experimental tools, for both applied science and fundamental research.

Culturing plant cells and tissuein vitromakes some special demands on laboratory facilities, although many large laboratories will have most of the equipment necessary for at least initial experiments with plant tissue cultures. The primary requirement for successful plant tissue culturein vitrois the ability to produce and culture the tissue aseptically. Plant cell cultures tend to grow very slowly and in most cases require a rich culture medium, which means that contamination with a range of microbial organisms can present a real problem.

Plant cell cultures also need to be kept in defined, controlled environments. In many respects, this can be achieved through the choice of culture vessel, which for many plant tissue cultures are relatively simple vessels such as petri dishes. These cultures though, will require maintenance in growth rooms that allow control of parameters such as temperature and lighting regime. This requirement may place a considerable burden on laboratories that utilize plant tissue cultures on a large scale, as specialized growth facilities can be expensive. On a smaller scale, many “cabinets” or growth chambers are available that allow plant tissue to be cultured on a small scale at a reasonable price.

Once established, plant cell cultures facilitate long‐term growth of uniform plant material and through precise manipulation of the culture environment, permit studies on such diverse topics as plant development, cell division, secondary metabolism, and plant propagation.
Polyhydroxyalkanoates (PHAs): Separation, Purification and Manufacturing Methods
Authors: Chen Guo‐Qiang
Published: April 2010

Polyhydroxyalkanoates (PHAs) function to provide bacteria with resistance. PHAs with diverse structures have been developed for various applications including fermentation, materials, packaging, biomedicals, and biofuels. The most critical problem for commercial PHA production is the cost. For many years, recombinant bacteria have been constructed to produce various PHAs with various structures, monomer ratios, and molecular weights for the sake of lowering PHA production costs and improving PHA properties. In the future, we should develop continuous fermentation processes without sterilization, based on simple substrates. In addition, aqueous processes for PHA purification should be developed to further reduce the PHA production costs.
Polysiloxanes, Biocatalytic Functionalization
Authors: Fröhlich Peter , Bertau Martin
Published: April 2010

This article describes methods and reactions for the modification of silicones (polysiloxanes) by chemical and particularly biocatalytic catalysis with reagard to industrial applications. The properties of organosiloxanes are determined by functional groups attached lateral or terminal to the silicone backbone by alkyl spacers. Most well‐established processes by which oligo‐ or polysiloxanes are obtained, use hard reaction conditions, strong acids or bases as catalysts thus resulting in a broad distribution of molecular weight. Biocatalysis by enzymes and whole cells attains increasing relevance as an attractive approach of green chemistry due to physiological conditions of pH, temperature and high stereoselectivity. In a general synthetic route major functionalities represented by amino, hydroxy, vinyl, carboxylate or amide groups are introduced to the alkyl spacered organosiloxane bearing ester, amide, carbamate groups or other functionalities by hydrolysis, amidation and oxidoreductions. In particular for hydrolytic reactions of esters and carbamates grafted onto the backbone, lipases and esterases exhibit high synthetic potential, primarily in non‐conventional media. Hydrolases are available economically on an industrial scale. The biocatalytic functionalizations are generally performed in a two‐phase system of siloxan‐cosolvent and aqueous medium, for which reason the mass transfer of reactants, product and enzyme is limited at the interface. Different feasible methods are depicted to solve the problem by increasing the interface. Microreactors open up new scopes for biocatalytic modifications of organosiloxanes performed by lipase‐catalyzed production of aminosiloxanes. The proof‐of‐concept for biocatalysis in silicone chemistry is highlighted by an ecoefficiency study.
Porous Media, Applications in Biotechnology
Authors: Mota Manuel , Yelshin Alexander , Yelshina Inna
Published: April 2010

After describing the main characteristics of porous media (porosity, tortuosity, permeability, and diffusivity), the role of porous media in mass transfer is analyzed with the help of numerical examples. Significant differences between the behavior of inert and biological porous media with respect to the response to external factors are considered. Current and prospective applications of porous media in biotechnology and biomedicine are highlighted.
Soluble Protein Expression in Bacteria
Authors: Schein Catherine H.
Published: April 2010

This article summarizes methods for increasing the fraction of recombinant proteins expressed in a soluble form in the cytoplasmic fraction of bacteria. Many recombinant proteins, when expressed at very high levels in bacteria, form insoluble aggregates called inclusion bodies (IBs). Growth conditions can be manipulated to keep protein in a soluble form, including lowering the temperature during induction, choice of host strain and expression vector, or coculturing of proteins that assist in folding. Higher yields can be obtained by mutating the protein or fusing it with various linkers (which can also improve purification by enhancing column chromatography interactions). Eliminating protease or RNase recognition sites can stabilize the protein or mRNA, as can mutations that improve recognition by cofactors that assist in folding.

Methodology to simultaneously produce many different recombinant proteins in a soluble form has been developed as part of the structural genomics initiative; these can also be used to for scanning mutagenesis studies. High density bacterial cultivation can be used to produce gram per liter quantities of recombinant proteins at the industrial scale. However, maintaining high levels of soluble protein requires optimizing all aspects of growth, ranging from how the inoculum is stored, to medium details and bacterial harvesting and lysis.
Growth Factors: Protein Processing, Endocytosis, and Intracellular Sorting
Authors: Duex Jason , Sorkin Alexander
Published: April 2010

Growth factor (GF) receptors are extracellular receptors which, when bound by growth factors, initiate intracellular signaling for promoting cellular proliferation, survival, and differentiation. The amount of signaling is generally controlled by both the levels of growth factor and the levels of GF receptors present in the cell, particularly at the cell surface. This review will focus on the mechanisms of endocytosis and postendocytic trafficking that serve to control the levels of GF receptors. The classical experimental system used to investigate these processes is the endocytosis of GF receptors that possess intrinsic tyrosine kinase activity, known as receptor tyrosine kinases (RTKs). We will use the prototypical RTK, epidermal growth factor receptor (EGFR), as the model GF receptor in this discussion since much of the data leading to the current understanding of GF receptor endocytosis was generated using this receptor.Growth factor (GF) receptors are extracellular receptors which, when bound by growth factors, initiate intracellular signaling for promoting cellular proliferation, survival, and differentiation. The amount of signaling is generally controlled by both the levels of growth factor and the levels of GF receptors present in the cell, particularly at the cell surface. This review will focus on the mechanisms of endocytosis and postendocytic trafficking that serve to control the levels of GF receptors. The classical experimental system used to investigate these processes is the endocytosis of GF receptors that possess intrinsic tyrosine kinase activity, known as receptor tyrosine kinases (RTKs). We will use the prototypical RTK, epidermal growth factor receptor (EGFR), as the model GF receptor in this discussion since much of the data leading to the current understanding of GF receptor endocytosis was generated using this receptor.
Protein Ultrafiltration
Authors: Reis Robert Van , Zydney Andrew L.
Published: April 2010

Protein ultrafiltration is a pressure‐driven membrane process used for the concentration and/or purification of protein solutions. Ultrafiltration membranes typically have mean pore size between 10 and 500 Å, which is intermediate between reverse osmosis and microfiltration. Although ultrafiltration has often been viewed as a purely size‐based separation, with species larger than the membrane pores being fully retained while smaller species pass freely, separation in ultrafiltration actually occurs because of differences in the rate of filtration of different components across the membrane in response to a given pressure driving force. Solute filtration rates, and thus the membrane selectivity, are determined by both thermodynamic (e.g. partitioning) and hydrodynamic (e.g. transport) interactions. Ultrafiltration is currently used throughout downstream processing for protein concentration, buffer exchange and desalting, protein purification, virus clearance, and clarification. Buffer exchange and desalting are typically accomplished using a diafiltration mode in which the low molecular weight components are washed away from the protein by simultaneously adding fresh buffer (or solvent) to the feed during ultrafiltration. Protein purification is accomplished using high performance tangential flow filtration, with the product collected in either the retentate or filtrate depending on the relative filtration rates. Virus filtration uses larger pore ultrafiltration membranes, which are permeable to protein but provide significant virus removal.
Temperature‐Dependent Molecular Adaptations, Microbial Proteins
Authors: Kumar Sandeep , Singh Satish K. , Gromiha M. Michael
Published: April 2010

This review seeks to present an update on the temperature‐dependent molecular adaptations shown by proteins from psychrophilic, thermophilic, and hyperthermophilic microorganisms. The temperature stress for life on Earth is ancient. Hence, there are multiple routes to psychrophily and thermophily. Electrostatic optimization of protein surfaces, active sites, and subunit interfaces are a frequent route. This natural manipulation of protein stability and solubility via surface electrostatics modulation has many potential applications. Here, we discuss how this principle could be used in a structure‐based biotherapeutic drug design and development.
Reverse Micelles, Enzymes
Authors: Kolisis Fragiskos N. , Stamatis Haralambos
Published: April 2010

Reverse micelles or w/o microemulsions have found wide applications in enzymology, protein chemistry and biocatalysis. Biocatalysis based on reverse micelles, is one of the earliest methodologies where microemulsions were introduced to solubilize enzymes in organic solvents. Reverse micelles have been associated to the idea of a microreactor where the enzyme can be sheltered and protected from solvent detrimental effects providing a unique microenvironment for the enzymes to react with water insoluble or poorly soluble substrates present in the organic phase. The most often investigated enzymes in microemulsions are lipases, because these enzymes are very stable and active in this medium. This review focuses on the fundamental aspects of enzymes encapsulation in reverse micelles, as well as on biotechnological applications based on these systems as reaction media for biotransformations using mainly lipase‐catalyzed processes.
Biosurfactants, Rhaminolipid, Microbial Production
Authors: Walter Vanessa , Syldatk Christoph , Hausmann Rudolf
Published: April 2010

Rhamnolipids are versatile and environment‐friendly biosurfactants composed of a hydrophilic rhamnose unit and a hydrophobic fatty acid part. This article covers all aspects of rhamnolipid biosurfactants production, from production strains to downstream processing.

Features and possible applications of rhamnolipids are illustrated and their biosynthesis is reviewed. Production strains, cultivation strategies, and recovery methods for rhamnolipids are presented from a commercial point of view. Nonpathogenic production strains, which are rarely used for rhamnolipid production, are presented and discussed. Currently rhamnolipids are noncompetitive with established bulk surfactants due to the high production costs. In the final section, the limitations of current rhamnolipid production processes are highlighted and research demands are discussed.
Sampling and Sample Handling for Process Control
Authors: Mattiasson Bo , Hedström Martin
Published: April 2010

Sampling and sample handling are crucial steps in monitoring and control of bioprocesses. Reproducibility in sampling and handling of the sample are key issues when developing new analytical tools. One of the problems with biotechnological processes is that often, microorganisms or enzymes are present in the sample and their activities have to be stopped in the sampling moment, otherwise the composition of the sample may change before analysis is carried out.

Integrated processing of samples can be carried out using flow‐injection analysis with different processing steps such as dialysis, dilution, reagent addition etc.

This area is attracting increasing interest now when industrial biotechnology is addressing processes with relatively low margins and where efficient process technology is a prerequisite.
Secretion of Heterologous Proteins, Gram‐Positive Bacteria,Lactococcus lactis
Authors: Morello Eric , Poquet Isabelle , Langella Philippe
Published: April 2010

Numerous Gram‐positive bacteria are used to produce heterologous proteins allowing easy protein secretion and purification. Among them, lactic acid bacteria (LAB) are interesting hosts since they secrete heterologous protein as both, cell factories and mucosal proteins delivery vectors. For this purpose,Lactococcus lactis, the model LAB, has been widely studied. Here, we review lactococcal expression and secretion systems that have been widely used and developed for heterologous protein production. These systems are based upon improved expression/secretion vectors carrying either inducible or constitutive promoters that allow a tight control of the heterologous protein expression level. These expression systems can include the use of characterized signal sequences as signal‐peptide or synthetic propeptide to drive efficient heterologous protein secretion into the extracellular medium. In parallel, huge knowledge acquired on protein secretion process in model bacteria has allowed us to identify some bottlenecks in processes much as translocation across the membrane, folding and degradation steps. Based on these studies, we describe complementary strategies consisting of host strain modifications to overcome these bottlenecks inL. lactis. Together, these studies are contributed to makeL. lactisand other LABs attractive hosts and efficient cell factories for production and delivery of heterologous secreted proteins.
Steroid Bioconversion
Authors: Fernandes Pedro , Cabral Joaquim M.S.
Published: April 2010

Steroids constitute a particular class of lipids characterized by a typical tetracyclic skeleton, composed of one five‐member ring and three fused six‐member rings. Steroids are widely used as therapeutic agents and since their inception in the market, research efforts have been made in order to improve production processes as well as to develop novel synthetic molecules, with enhanced efficiency and reduced side effects. Given the complexity of the steroid skeleton, total chemical synthesis of given steroid molecules is hardly an effective approach; hence, steroid production processes rely on chemical modifications of educts that structurally resemble the targeted product. Still, steroid molecules present multiple chiral centers, a feature that makes particularly appealing the use of the selective microbial catalysts to provide a pathway that does not require protection, and additional deprotection steps. Furthermore, bioconversions are performed in a milder, greener environment, as compared to the purely chemical approach. The present work aims to provide an overview of steroid bioconversions. The potential of biologic agents (microbial cells/enzymes) to catalyze the conversion of a wide array of steroid educts will be presented, with particular emphasis on those that have achieved particular relevance, as well as on key aspects within the field. The chapter ends with the perspective trends in the field of steroid bioconversions
Tyrosine Phenol‐Lyase
Authors: Katayama Takane , Kumagai Hidehiko
Published: April 2010

Tyrosine phenollyase (TPL) is a pyridoxal 5′‐phosphate‐dependent enzyme that normally catalyzes α,β‐elimination ofL‐tyrosine to produce pyruvate, ammonia, and phenol. The enzyme also catalyzes β‐elimination reaction, alanine racemization, and reverse reaction of α,β‐elimination. The finding of the reverse reaction enabled us propose a reaction mechanism employed by TPL. Recent structural and mutational studies verified the reaction mechanism and also revealed the catalytically important residues of this enzyme. The regulatory mechanism underlying the expression of TPL was also elucidated. TyrR and cyclic AMP receptor protein were identified as being responsible for the tyrosine‐mediated induction and carbon catabolite repression of the enzyme, respectively. These biochemical and genetic studies were developed to efficiently produce 3,4‐dihydroxyphenyl‐L‐alanine, a therapeutic agent for Parkinson's disease.
Virus Removal from Plants
Authors: Sherwood John L.
Published: April 2010

Viruses will cause a steady decline in plant vigor, quality, and subsequent loss of yield. The lack of inexpensive and reliable curative agents for the elimination of viruses from plants that are growing in the field, orchard, or landscape has resulted in the development of methods for producing virus‐free plant materials to replace material that is chronically infected or to assure that newly planted material or plant material exchanged between locations is free of virus. Therapy may include heat treatment alone or in combination, culture of totipotent cell clusters such as meristems, and use of compounds that affect virus replication. Though plant material may emerge virus‐free, it is not virus‐resistant. Hence, a vigorous approach to monitor for viruses must be considered when the plant material is used.
Acclimatization of Plantlets fromIn vitroto the Ambient Environment
Authors: Preece John E.
Published: April 2010

Acclimatizing, hardening‐off, or conditioning plantlets from the in vitro to the ambient environment can be a challenge that may result in death or damage to a large percentage of micropropagated plants. When grown in the high humidity, low light environment often encountered in vitro, leaves have altered anatomy; poor cuticle development, with low amounts of epicuticular waxes; and the stomatal apparatus functions poorly with stomata remaining open, even in darkness or in stressful conditions. Gradually acclimatizing the plantlets to the ex vitro environment using mist, fog, or high humidity combined with shading will reduce losses. Light levels can be gradually raised and relative humidity gradually lowered as the plantlets grow new leaves and their shoots elongate. Eventually, plants will thrive in ambient conditions. Soil additives, such as mycorrhizal fungi combined careful attention to sanitation will also aid survival.
Bioreactors, Continuous Culture of Plant Cells
Authors: Ten Hoopen H.J.G.
Published: April 2010

Introduction

Assumptions in Continuous Culture Theory and Their Pitfalls

The Practical Setup of a Continuous Culture

Mathematical Description of Continuous Culture

Applications of the Continuous Cultivation of Plant Cells

Nomenclature

References
Dicotyledons
Authors: Ramsay Margaret M.
Published: April 2010

Introduction

Seed Germination

Micropropagation

Axillary Shoot Production

Adventitious Bud Formation

Callus and Cell Suspension

Somatic Embryogenesis

Limitations: Contamination, Hyperhydricity, Recalcitrance and Oxidative Browning

Plant Genetic Engineering

Cryopreservation

References
Antibody Manufacture, Disposable Systems
Authors: Eibl Regine , Eibl Dieter
Published: April 2010

The growing demand for biotherapeutics and, in particular, antibodies has resulted in an increasing use of disposables over the last ten years. This concerns both, process development and commercial manufacturing, where animal cells are grown in suspension or on microcarriers. The use of disposable devices have been implemented in all three stages of biotechnological production processes: (i) upstreaming, (ii) downstreaming as well as (iii) final formulation and filling. The majority of applications are to be found in upstream processing. Here, disposable expendable laboratory items, simple peripheral elements, and equipment for unit operations are well‐established. Among the components listed, disposable bioreactors have achieved the highest growth rate over the last year.

Following an introduction in which the term “single‐use” is defined, a general overview of single‐use devices in antibody production processes is given. We focus on frequently used disposable bioreactor types, their characteristics, and obtainable results, and discuss apparent trends for disposables in antibody manufacture.
Biotransformation of Synthetic Fibers
Authors: Silva Carla , Matamá Teresa , Cavaco‐Paulo Artur
Published: April 2010

Enzyme technology has been developed from the biotransformation of small and homogeneous substrates to large and heterogeneous ones. In this article, synthetic fibers are presented as suitable substrates for enzymatic action. Their hydrophobic nature makes them uncomfortable to wear, leading also to static cling and stain retention. Therefore, surface modification has been employed in order to overcome these negative properties and impart the desired properties. The use of enzymes is becoming an attractive alternative to classical methodologies avoiding the use of chemicals, being at the same time less aggressive for the fabrics and an environmentally friendly process.

This article intends to be an overview of the modifications of the three main synthetic fibers used in the textile market: poly(ethyleneterephthalate), polyamide, and acrylic. The enzymes used for fiber modification as well as the methodologies used for application and hydrolysis products' detection are presented.
Glycochips
Authors: Hillringhaus Lars , Seibel Jürgen
Published: April 2010

An overview is given about the different carbohydrate‐array types as well as immobilization and read out techniques, which offer a broad spectrum for many applications used in academia and the industries. Also the glycan acquisition is discussed, which is a fundamental task since pure and defined glycans are required to gain sound results. Finally, applications are mentioned, which give an impression of how glycan arrays impact the understanding of glycan‐mediated biological processes and give rise to new medical applications.
History of Biotechnology
Authors: Buchholz Klaus
Published: April 2010

In the early years, highly esteemed drinks, such as beer and wine were produced at home, or acids were produced as the preservative agent for storable food, by using yeast or bacteria; but this was without conscious knowledge.

Barley, the basic raw material for beer preparation, not bread making, was the first cultured cereal (about 10,500 BC). The first written document on food preparation by the Sumerians, is 6000 years old and is on brewing.

In the late eighteenth and nineteenth centuries, heavy controversies about theories, vitalist, and chemical resulted in the creation, as well as reversal of theories and paradigms; strong interaction and stimulus from arts and industries prompted continuing progress. Last but not least, it was accepted that products of living organisms were not to be treated differently from inorganic materials. Pasteur's work led to the banishing of the idea which had been anathema to exact scientific inquiry in the life sciences, namely, “spontaneous generation.” He established the science of microbiology by developing pure monoculture in sterile medium and provided significant technical progress in brewing, wine making, and other processes.

The requirements for antibiotics and vaccines, to combat disease and chemical components for explosives, particularly in war time, stimulated exact studies in producing products from microbial fermentations. Progress in research led to the emergence of new disciplines: microbiology, during the second half of the nineteenth century; biochemistry by the beginning of the twentieth century; and biotechnology by the end of the twentieth century, respectively. Basic researches in biochemistry and molecular biology dramatically widened the field of life sciences and at the same time unified them considerably. The scope of accessible products and services expanded enormously.
Enzyme‐Catalyzed Synthesis of Nonnatural or Modified Nucleosides
Authors: Sinisterra Jose‐Vicente , Alcántara Andrés‐Rafael , Almendros Marcos , Hernáiz María J. , Sánchez‐Montero José‐María , Trelles Jorge
Published: April 2010

Nucleosides and their analogs possess several pharmacological activities, so that many strategies have been developed in order to prepare these compounds. The chemical synthesis of these labile and polyfunctional molecules is very complex because many protection–deprotection steps are involved in their preparation. In this sense, biocatalyzed synthesis of nucleosides using either whole cells or enzymes is a greener alternative to conventional methodologies; not only are the number of synthetic steps reduced, but also the waste production is minimized, while the required solvents are environment‐friendly.

Some new enzymes, showing different specificities, have become available in recent years. In fact, advances in fermentation, purification, and immobilization techniques have resulted in the production of more stable biocatalysts at significantly reduced cost. Automated screening, new metagenomic techniques, directed evolution, and metabolic engineering have led to the production of novel customized industrial enzymes. For those reasons, there are a large number of patents in Europe and United States of America that are related to these advances. In the present review, we describe many examples used at laboratory scale, and some industrial applications that are not that extensively implemented now will also be commented on. Nevertheless, new scientific developments promise to overcome these drawbacks in the near future.
Antibody Production: Human, Recombinant
Authors: Dübel Stefan
Published: April 2010

Recombinant antibodies are not only the largest, but also the most rapidly growing group of protein therapeutics. In fact, only the development of an increasing number of recombinant technologies was the trigger for the broad success of monospecific antibodies in the clinics, which started in the last decade. By now, 24 antibodies are approved for clinical use, the vast majority of them having been modified toward a more “human” primary sequence. In addition to various humanization methods for mouse hybridoma‐derived monoclonal antibodies, in particular, novel methods for the generation of fully human antibodies were developed. Most importantly, approaches allowingin vitroselection, that is, the isolation of specific interactions outside of, and independent from a living immune system, gained increasing importance to generate clinically useful human antibodies. The most widely used method here is phage display. This method is based on the selection of antibody genes by their encoded antigen‐binding function in an affinity‐based enrichment step. After getting a recombinant antibody clone, the fusion of other proteins/protein domains lends itself to the development of new characteristics in recombinant antibodies, which nature cannot provide. Furthermore, through the production of recombinant antibodies in different organisms, new possibilities for commercial mass production have arisen.