bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of melanin on enzymatic hydrolysis of cellulosic waste
Authors: Ray R. M. , Desai J. D. 
Published: December 2004

AbstractWood waste powder from Tectona grandis containing melanin was less susceptible to enzymatic hydrolysis than powder without melanin. About a 53% increase in saccharification was noted when melanin was removed. Melanin caused inhibition to all cellulolytic enzymes, but in different degrees. Endo‐β‐1,4‐glucanase and β‐glucosidase were markedly inhibited when melanin was preincubated with enzyme, while exo‐β‐1,4‐glucanase was severely inhibited when melanin was preincubated with substrate. The latter was found to be dependent on the contact time. The activities of endo‐β‐1,4‐glucanase and β‐glucosidase were noncompetitively inhibited by melanin.
Enzymic saccharification of sugar beet pulp
Authors: Moloney A. P. , O'Rorke A. , Considine P. J. , Coughlan M. P. 
Published: December 2004

AbstractCulture filtrates of Talaromyces emersonii UCG 208 grown on beet pulp can convert the polysaccharide components of this agricultural waste to soluble sugars. The saccharification process is facilitated if the pulp is milled or incubated with alkali or peracetic acid before addition of enzyme. However, treatment of unmilled pulp with commercial pectinase prior to incubation with Talaromyces filtrate is also very effective; under suitable conditions, complete hydrolysis of total polysaccharides has been achieved.
Degradation of a washed carrot preparation by cellulases and pectinases
Authors: Sreenath H. K. , Frey M. D. , Radola B. J. , Scherz H. 
Published: December 2004

AbstractA washed carrot substrate, prepared with high yields and easy handling properties, was found to be a suitable substrate for studying cellulolytic and pectinolytic degradation processes. A cellulase from Trichoderma reesei, and Rohament P, a macerating enzyme from Aspergillus alleaceǔs in endopolygalacturonase, degraded the washed carrot substrate to an extent of 60%. With the combined action of both enzymes, degradation was more than 80%. Simultaneous action of both enzymes was more efficient than their sequential use. The effect of temperature, pH, incubation time, enzyme concentration, and substrate concentration on the degradation by the single enzymes and their mixture were studied. Gas chromatographic sugar analysis revealed that Rohament P liberated glucose, arabinose, and galactose in the low‐molecular‐weight fraction obtained by ultrafiltration, in addition to high amounts of galacturonic acid. These carbohydrates were also found in the high‐molecular‐weight fraction (retentate) together with rhamnose and mannose. Cellulase BC released mainly glucose, although galacturonic acid, arabinose, xylose, and mannose were also detected both in the ultrafiltrate and retentate. Morphologically, during Rohament P degradation of the washed carrot substrate, damaged tissues and disintegrated cells were seen, whereas on cellulase BC action mainly disintegrated cell walls were observed.
Sterilization of oils: Data to support the use of a continuous point‐of‐use sterilizer
Authors: Bader F. G. , Boekeloo M. K. , Graham H. E. , Cagle J. W. 
Published: December 2004

AbstractThe continuous slow feed of animal and vegetable oils is frequently found to be an economically attractive method for maintaining antibiotic fermentations at a highly productive rate. The sterilization of oil feeds can present a major problem in the production plant. In this article, we present data and methodology on the kinetics of the thermal sterilization of No. 2 lard oil and soybean oil. It was also determined that dry heat sterilization condition could occur if dry spores were added to dry oil. This condition could only be partially alleviated by the addition of water to the oil. The theory and design of a small tubular coil continuous sterilizer for sterilizing oils at the point of use is also presented. This type of sterilizer is economical and versatile and simplifies control and instrument requirements. It provides a realistic alternative to the use of sterile feed tanks and sterile headers.
Immobilization of enzymes in porous supports: Effects of support–enzyme solution contacting
Authors: Dennis K. E. , Clark D. S. , Bailey J. E. , Cho Y. K. , Park Y. H. 
Published: December 2004

AbstractProteins have been immobilized in porous support particles held in a fixed‐bed reactor through which protein solution is continuously circulated. Changing the recirculation flow rate alters the observed immobilization kinetics and the maximum enzyme loading which can be achieved for glucose oxidase and glucoamylase on carbodiimide‐treated activated carbon and for glucoamylase immobilized on CNBr–Sepharose 4B. Direct microscopic examination of FITC‐labelled protein in sectioned Sepharose particles and indirect activity–loading studies with activated carbon–enzyme conjugates all indicate that immobilized enzyme is increasingly localized near the outer surface of the support particles at larger recirculation flow rates. Restricted diffusion of enzymes may be implicated in this phenomenon. These contacting effects may be significant considerations in the scaleup of processes for protein impregnation in porous supports, since apparent activity and stability of the final preparation depend on internal protein distribution.
Cholinesterase‐catalyzed resolution of D,L‐carnitine
Authors: Dropsy Eric P. , Klibanov Alexander M. 
Published: December 2004

AbstractAn enzymatic method for the preparative resolution of racemic carnitine (whose L‐isomer and its acyl‐derivatives have numerous therapeutical applications) has been developed. It is based on our finding that electriceel acetylcholinesterase hydrolyzes the D‐ but not the L‐isomer of acetylcarnitine. (Another cholinesterase tested, horse serum butyrylcholinesterase, is also stereospecific and hydrolyzes only the L‐isomer of butyrylcarnitine.) Acetylcholinesterase, covalently attached to alumina, was employed for the resolution of D,L‐carnitine; the latter was first chemically acetylated, then stereoselectively hydrolyzed with the immobilized enzyme, and finally the acetyl‐L‐carnitine and D‐carnitine produced were separated by ion‐exchange chromatography. Gram quantities of D,L‐carnitine were thereby resolved.
An operational strategy for unstable recombinant DNA cultures
Authors: Ryder D. F. , DiBiasio D. 
Published: December 2004

AbstractA simple operational strategy is shown to offer a viable means of enhancing plasmid stability in chemostat systems where plasmid loss is a common problem. Feedback control can be used to stabilize coexistence states, which are naturally unstable in the system investigated, and thus gurantee retention of the plasmid‐carrying strain. The strategy exploits the normally undesirable characteristics of substrate inhibited growth kinetics, and is illustrated with specific reference to methanolutilizing organisms. Since the methodology may be easily implemented in practice, it offers an alternative to costly environmental methods such as antibiotic addition.
Influence of the presence of Zymomonas anaerobia on the conversion of cellobiose, glucose, and xylose to ethanol by Clostridium saccharolyticum
Authors: Asther M. , Khan A. W. 
Published: December 2004

AbstractTo convert sugar mixtures containing cellobiose, glucose, and xylose to ethanol in a single step, the possibility of using a coculture consisting of Clostridium saccharolyticum and Zymomonas anaerobia was studied. In monoculture, C. saccharolyticum utilized all three sugars; however, it preferentially utilized glucose and produced acetic acid in addition to ethanol. The formation of acetic acid from the metabolism of glucose inhibited the growth of C. saccharolyticum and, consequently, the utilization of cellobiose and xylose. In monoculture, Z. anaerobia utilized glucose at a rate of 50 g/L day, but it did not ferment cellobiose or xylose. In coculture, Z. anaerobia converted most of the glucose to ethanol during the lag phase of growth of C. saccharolyticum, which then converted cellobiose and xylose to ethanol. The use of this coculture increased both the rate and the efficiency of the conversion of these three sugars to ethanol, and produced relatively small amounts of acetic acid.
Effect of dilution on carboxymethylcellulase and xylanase assays
Authors: Cauchon Nicole , Leduy Anh 
Published: December 2004

AbstractIt has been demonstrated that the dilution of samples prior to the carboxymethylcellulase and xylanase assays causes serious discrepancies in the numerical values obtained for the enzyme activities. Even when the sample is assayed with the identical procedure, one could obtain different numerical values of the enzyme activity U depending on how much this sample has been diluted before the enzyme assay. Two crude commercial cellulase samples of Aspergillus niger and Trichoderma viride as well as the culture filtrate of our newly isolated acidophilic fungus have been used for the demonstration. An empirical method for reporting the cellulolytic activity by taking into account this dilution effect is proposed.
Continuous ethanol fermentation using immobilized yeast cells
Authors: Nagashima Minoru , Azuma Masaki , Noguchi Sadao , Inuzuka Keiichi , Samejima Hirotoshi 
Published: December 2004

AbstractGrowing cells of Saccharomyces cerevisiae immobilized in calcium alginate gel beads were employed in fluidizedbed reactors for continuous ethanol fermentation from cane molasses and other sugar sources. Some improvements were made in order to avoid microbial contamination and keep cell viability for stable long run operations. Notably, entrapment of sterol and unsaturated fatty acid into immobilized gel beads enhanced ethanol productivity more than 50 g ethanol/L gel h and prolonged life stability for more than one‐half year. Cell concentration in the carrier was estimated over 250 g dry cell/L gel. A pilot plant with a total column volume of 4 kL was constructed and has been operated since 1982. As a result, it was confirmed that 8–10%(v/v)ethanol‐containing broth was continuously produced from nonsterilized diluted cane molasses for over one‐half year. The productivity of ethanol was calculated as 0.6 kL ethanol/kL reactor volume day with a 95% conversion yield versus the maximum theoretical yield for the case of 8.5% (v/v) ethanol broth.
Economic evaluation of alternative ethanol fermentation processes
Authors: Maiorella B. L. , Blanch H. W. , Wilke C. R. 
Published: December 2004

AbstractEleven alternative fermentation schemes for ethanol production are compared. Conventional batch, continuous, cell recycle, and immobilized cell processes, as well as membrane, extraction, and vacuum processes which remove ethanol from the broth selectively as it is produced, are considered. The processes are compared on identical bases using a consistent model for the yeast metabolism. Both molasses and cellulose hydrolyzate are considered as feeds. Optimized ethanol plants, including feed preparation, fermentation, and product recovery sections are designed and total costs are projected.
Studies on cellulase production by a mutant—penicillium funiculosum uv‐49
Authors: Joglekar A. V. , Karanth N. G. 
Published: December 2004

AbstractIn search of hypercellulolytic microorganisms, ultraviolet irradiation carried out with Penicillium funiculosum has yielded a superior mutant. The investigations reported in this article are shake flask studies on some important nutritional requirements of the mutant, namely, nitrogen source, carbon source, and inducers. The mutant shows an ability to metabolize inorganic nitrogen sources like urea and sodium nitrate both for growth and enzyme production. A comparison of the long‐term saccharification ability and the utilization efficiency of the mutant enzyme with those reported in the literature is also carried out, showing the superior performance of the mutant enzyme.
Modification of wheat straw in a high‐shear mixer
Authors: Carr M. E. , Doane W. M. 
Published: December 2004

AbstractWheat straw (Ws)was treated in a pilot‐scale continuous mixer to disrupt the lignin–hemicellulose–cellulose (LHC) complex. An efficient and practical method was desired to remove lignin and hemicellulose (pentosans)rapidly and efficiently from the lignocellulose complex and to make the cellulose accessible to enzymatic hydrolysis. Milled WS in the presence of various chemicals in aqueous solutions was extruded from the mixer under several processing conditions. Chemicals used were sodium hydroxide (NaOH) sodium sulfide (Na2S), anthraquinone (AQ), anthrahydroquinone (AHQ), hexamethylenediamine (HMDA), hexamethylenetetramine (HMTA) hydrogen peroxide (H2O2), and ferrous ammonium sulfate (FAS), which were used alone and in selected combinations. Concomitantly, WS was treated in laboratory batches using similar reaction conditions, except for mixing and shearing. In extrusion treatments of WS at 20% concentration at 97°C for 5.5 min with NaOH (15.7%, dry WS basis), NaOH (15.7%) + AHQ (0.3%), and NaOH (12.7%) + Na2S (5.0%), 64–72% of the WS lignin and 36–43% of the pentosans were removed from aqueously washed extrudates (residues). This compares with 46–56% and 23–27%, respectively, for batch treatments. AHQ and Na2S enhanced delignification. Cellulase treatment of the residues, which contained about 99%of the WS cellulose, converted 90–92%of the cellulose to glucose compared with 61–69%for the batch pretreatments. Treatments of WS with amines and H2O2 (alone or combined with NaOH)were less effective for LHC disruption. In all instances the relatively high‐shear extrusion treatments were superior to the laboratory‐batch treatments.
Ion exchange/complexation of the uranyl ion by Rhizopus biosorbent
Authors: Treen‐Sears Margaret E. , Volesky Bohumil , Neufeld Ronald J. 
Published: December 2004

AbstractNonliving biomass of nine Rhizopus species effectively sequestered the uranyl ion from solution, taking up 150–250 mg U/g dry cells at 300 ppm U equilibrium concentration in solution, and 100–160 mg U/g dry cells with 100 ppm U in solution. The affinity of this biosorbent for the uranyl ion was found to be affected by timing of harvesting and medium composition. Uptake of the uranyl ion by nonliving biomass of Rhizopus oligosporus was due to ion exchange or complexation, since binding was reversed by the addition of complexing ligands or the reduction of pH to a value less than 2. Uptake isotherms were interpreted in terms of a model of multiple equilibria. At pH ≤ 2, or in the presence of NO, Cl−, SO, or EDTA (ethylenediamine–tetra‐acetate), the quantity of UO that was bound was a constant fraction of that bound at pH 4 in the absence of ligands. This action indicated simple competition for uptake sites between H3O+ and UO for uptake sites, or for UO between the biomass and ligands in solution. If oxalate or thiocyanate was present, however, the complexed species were sequestered by the biomass. Biomass of Rhizopus arrhizus, which grew as pellets, was subsequently used in a packed sorption column where it exchanged hydrogen ions for uranyl ions (2 H+: 1 UO). Concentrated uranyl solutions were eluted in sulfuric or nitric acids, and the biomass was reused eight times with no apparent deterioration of the biosorbent.
Cellular reporoduction and extracellular polymer formation by Pseudomonas aeruginosa in continuous culture
Authors: Robinson Joseph A. , Trulear Michael G. , Characklis William G. 
Published: December 2004

AbstractThe kinetics of cellular reproduction and the rate and extent of synthesis of extracellular polymeric substances (EPS) were investigated for P. aeruginosa growing in glucose‐limited chemostats. μmax and Ks estimates of 0.4 h−1 and 2 mg glucose C/L, respectively, at 25°C were obtained for this bacterium. The extent of EPS formation was inversely related to the growth rate of P. aeruginosa. The rate of EPS formation had both growth‐ and non‐growth‐associated components. The growth‐associated polymer formation rate coefficient (k) was 0.3 mg polymer C/mg cellular C and the non‐growth‐associated polymer formation rate coefficient (k′) was 0.04 mg polymer C/mg cellular C/h. The values for k and k′ must be regarded as provisional since the product formation data were quite variable at low dilution rates. Estimates of the cellular (Yx/s) and polymer (Yp/s) yield coefficients were 0.3 mg cellular C/mg glucose C and 0.6 mg polymer C/mg glucose C, respectively. Most of the non‐growth‐associated consumption of glucose detected was due to exopolymer formation.
Estimation of yield, maintenance, and product formation kinetic parameters in anaerobic fermentations
Authors: Oner M. D. , Erickson L. E. , Yang S. S. 
Published: December 2004

AbstractIn many anaerobic fermentation processes, high energy bonds in adenosine triphosphate (ATP) are produced when available electrons are converted from organic substrate into extracellular organic products such as ethanol. The true growth yield and maintenance parameters are directly related to the product formation kinetic parameters for these anaerobic processes. Methods are presented which allow all of the experimental measurements to be used simultaneously to estimate these parameters. Results are presented for several different anaerobic fermentations.
Dried calcium alginate/magnetite spheres: A new support for chromatographic separations and enzyme immobilization
Authors: Burns Mark A. , Kvesitadze George I. , Graves David J. 
Published: December 2004

AbstractDried spheres made from an alginate solution containing magnetite particles have excellent potential as a support for enzyme immobilization and chromatographic applications. The beads were found to be much stronger than gels such as polyacrylamide and dextran, indicating that high flow rates and pressures could be used in column separations. The support withstood not only temperatures of up to 120°C, but also most pH values and common solvents. While some solutions, such as phosphate buffers, dissolved the spheres, stabilization with Tyzor TE® eliminated this problem. The physical properties of the beads include a glasslike density of 2.2 g/mL, excellent sphericity, low porosity, and a narrow size distribution. The magnetite present in the support allows the beads to be used for magnetic separations such as high gradient magnetic filtration. Their high degree of microroughness provides a large exposed surface area for enzyme and ligand binding. Mixed Actinomyces fradiae proteases and Aspergillus niger α‐amylase, two enzymes representative of classes which attack large substrates, were immobilized on the bead's surface with high activity and stability. A cyanuric dye which can be used in chromatographic applications (Cibacron Blue F3GA®) was also readily coupled to the surface of this support with good yield. The support should have a wide range of applications in bioseparation and immobilized biochemical technology.
Design of a system for the control of low dissolved oxygen concentrations: Critical oxygen concentrations for Azotobacter vinelandii and Escherichia coli
Authors: Chen J. , Tannahill A. L. , Shuler M. L. 
Published: December 2004

AbstractThe physiological activity of microorganisms in environments with low dissolved oxygen concentrations often differs from the metabolic activity of the same cells growing under fully aerobic or anaerobic conditions. This article describes a laboratory‐scale system for the control of dissolved oxygen at low levels while maintaining other parameters, such as agitator speed, gas flowrate, position of sparger outlet, and temperature at fixed values. Thus, it is possible to attribute in dilute nonviscous fermentations all physiologic changes solely to changes in dissolved oxygen. Experiments were conducted with Azotobacter vinelandii and Escherichia coli. Critical oxygen concentrations for growth (that value of oxygen allowing growth at 97% of μmax) were measured as 0.35 ± 0.03 mg/L for A. vinelandii and 0.12 ± 0.03 mg/L for E. coli. These values are significantly different from the commonly quoted values for critical oxygen concentrations based on respiration rates. Because of the superior dissolved oxygen control system and an improved experimental protocol preventing CO2 limitation, we believe that the values reported in this work more closely represent reality.
Measurements of lactate concentration using lactate oxidase and an electrochemical oxygen sensor
Authors: Makovos E. B. , Liu C. C. 
Published: December 2004

AbstractLactate oxidase was used in combination with an electrochemical dissolved oxygen sensor to measureL‐lactate concentration in the physiological saline solution. The rate of oxygen consumption was found to have an excellent linear relationship with the lactate concentration on a log‐log scale in the lactate concentration range of 0.3–25 mM. This detection does not require additional reagents and can be developed into a simple method ofL‐lactate determination. The effects of the temperature and pH of the solution on the reaction rate were investigated and discussed.
Analysis of a diffusion‐limited hollow fiber reactor for the measurement of effective substrate diffusivities
Authors: Davis Mark E. , Watson Layne T. 
Published: December 2004

AbstractMathematical analyses of a diffusion‐limited hollow fiber reactor for the measurement of effective substrate diffusivities are presented. An analytical solution to the mathematical model with a first order substrate consumption rate is used to show that the procedure of Webster and Shuler1 is incorrect. A rigorous analysis that requires numerical solution is also outlined for any form of the substrate consumption rate. These analyses allow for more accurate estimations of effective substrate diffusivities since they should be used in conjunction with integral reactor behavior.
Automatic supplementation of minerals in fed‐batch culture to high cell mass concentration
Authors: Suzuki Takahiro , Mori Hironori , Yamané Tsuneo , Shimizu Shoichi 
Published: December 2004

AbstractAutomatic constant‐value control of mineral ions was attempted in semibatch culture of high cell mass concentration (more than 150 g dry cell/L) with ethanol and ammonia feeds. Equations were derived from the mass balance principle to calculate the required concentration of each mineral ion in the mineral feed solution, taking into account both the decrease in the volume of the culture supernatant as a proportion of the whole culture broth and the increase in the volume of the whole culture broth during the cultivation. The mineral solution was supplied automatically, linked either with ethanol feed or ammonia water feed. The actual concentrations of mineral ions could be kept within small variations. To adjust the supplementation in accordance with the culture change from oxygen sufficiency (early growth phase) to oxygen deficiency (later growth phase), the concentration of each mineral ion was altered stepwise when the dissolved oxygen concentration fell to zero. The mineral supplementation gave better results coupled with ethanol feed than with ammonia feed. The mineral ions studied were K+, Mg2+, Na+, Fe2+, Zn2+, Ca2+, Co2+, Cu2+, Mn2+, NH+4, PO and SO.