bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of collagen‐bound sorbitol dehydrogenase in the rotating membrane reactor: Opposite variations of affinity constants under diffusional limitations
Authors: Paul François , Coulet Pierre R. , Gautheron Danièle C. , Engasser Jean‐Marc 
Published: December 2004

AbstractSorbitol dehydrogenase was bound to the surface of acyl‐azide‐activated collagen membranes and its kinetics was investigated as a model of two‐substrate or cofactor‐requiring enzyme reactions. The study was performed with the “rotating membrane reactor” especially designed to obtain a precise variation of the external mass‐transfer coefficient, and thus the direct visualization of diffusional effects on the bound enzyme behavior. Diffusional limitations for NADH were found to decrease the apparent affinity for NADH, but to increase the apparent affinity for fructose. Such opposite effects of diffusional limitations on apparent affinities are generally applicable to reactions involving two substrates or a substrate and a cofactor of widely different affinities.
Technical aspects of separation using aqueous two‐phase systems in enzyme isolation processes
Authors: Kroner K. H. , Hustedt H. , Granda S. , Kula M.‐R. 
Published: December 2004

AbstractTechnical aspects of the separation of aqueous two‐phase systems in a commercial separator were studied in detail. For the Gyrotester B, the smallest available separator, a flow rate of 200 ml/min and a length of the regulating screw in the outlet port of 13.5 mm were found as optimal operation parameters for the separation of a poly(ethylene glycol) (PEG)/dextran two‐phase system. In the presence of cells and cell debris the characteristics of the carrier two‐phase systems are changed, most notably the phase ratio. Nevertheless good separation and high throughput can be maintained up to 30% wet cell material in the complete system. Using this method the enzyme pullulanase was extracted from 6.65 kg Klebsiella pneumoniae in 88% yield in a single step in less than 2 hr. A yield of 90% was predicted for this step based upon laboratory data, indicating that the performance of the extraction and separation can be calculated with the necessary accuracy and the further scale‐up of the process should be accomplished quite easily. The hydrophilic polymers Constituting the phase system will often stabilize the enzymes, So that the separation can be carried out at room temperature without extensive cooling. The method of enzyme solubilization or cell disruption is not decisive for the successful extraction of the enzymes, the only limitation being the necessity to find a suitable two‐phase system where the desired product and the cells or cell debris will partition in opposite phases. This is shown for α‐glucosidase from Saccharomyces carlsbergensis and three aminoacyl‐tRNA‐synthetases from Escherichia coli. The results obtained demonstrate that aqueous two‐phase systems can be separated in commercially available separators with high capacity and efficiency. It can be expected that the advanced separation technology available from chemical engineering studies can also be used for the development of large‐scale isolation processes for enzymes involving liquid–liquid partitions.
Immobilized glucose oxidase–catalase and their deactivation in a differential‐bed loop reactor
Authors: Prenosil J. E. 
Published: December 2004

AbstractGlucose oxidase containing catalase was immobilized with a copolymer of phenylenediamine and glutaraldehyde on pumice and titania carrier to study the enzymatic oxidation of glucose in a differential‐bed loop reactor. The reaction rate was found to be first order with respect to the concentration of limiting oxygen substrate, suggesting a strong external mass‐transfer resistance for all the flow rates used. The partial pressure of oxygen was varied from 21.3 up to 202.6 kPa. The use of a differential‐bed loop reactor for the determination of the active enzyme concentration in the catalyst with negligible internal pore diffusion resistance is shown. Catalyst deactivation was studied, especially with respect to the presence of catalase. It is believed that the hydrogen peroxide formed in the oxidation reaction deactivates catalase first; if an excess of catalase is present, the deactivation of glucose oxidase remains small. The mathematical model subsequently developed adequately describes the experimental results.
Computer control of bakers' yeast production
Authors: Wang Henry Y. , Cooney Charles L. , Wang Daniel I. C. 
Published: December 2004

AbstractThe Biotechnology and Bioengineering study presented here was undertaken to demonstrate the usefulness of computer control for the production of yeast from molasses. A flexible control system was developed by using an on‐line computer for the monitoring of cell mass and employing anticipatory control to maintain the maximum productivity. Process disturbances were minimized by employing a multivariable feedback control system to prevent ethanol formation. The control strategy acted to keep overall conversion yield at its maximum level, about 0.5 g cell/ g sugar, while maintaining high volumetric productivity between 3 and 5 g/liter‐hr. Results are presented to show the effectiveness of simultaneous anticipatory and feedback contol in overcoming problems of oxygen starvation, molasses quality, and variable inoculum size.
Process analysis and optimal design of a fermentation process based upon elemental balance equations: Generalized semitheoretical equations for estimating rates of oxygen demand and heat evolution
Authors: Ho Lewis 
Published: December 2004

AbstractBased upon elemental balance equations, generalized semitheoretical equations are developed for estimating the rates of oxygen demand and heat evolution of a fermentation process. The results estimated by these equations are in good agreement with data obtained from yeast–hydrocarbon and yeast–carbohydrate fermentation processes for citric acid production. Furthermore, a direct relationship between rates of oxygen demand and heat evolution is derived with a correlation constant of 0.18 kcal/mM O2.The relationship has been verified by data of citric acid fermentation processes and also confirmed by published data. These derived equations would be useful for process design and optimization.
Activated‐sludge process dynamics with continuous total organic carbon and oxygen uptake measurements
Authors: Mona R. , Dunn I. J. , Bourne J. R. 
Published: December 2004

AbstractThe dynamic responses of a bench‐scale activated‐sludge process to step changes and square‐wave inputs in the feed flow and concentration were measured. Instrumentation permitted the continuous measurement of the oxygen uptake rate and dissolved organic carbon responses. Notable were the sensitivity of the oxygen uptake rate to process changes and the reliability of the dynamic oxygen electrode method. The responses were found to be greatly influenced by the organic loading, FS0/XV, which was incorporated into a load‐dependent kinetics model. Simulations showd good agreement with experiment in the case of the square‐wave disturbances. Because of the changing and complex nature of the activated sludge it was necessary to reestimate the parameter set for each run.
Studies on quantitative physiology of Trichoderma reesei with two‐stage continuous culture for cellulose production
Authors: Ryu Dewey , Andereotti R. , Mandels M. , Gallo B. , Reese E. T. 
Published: December 2004

AbstractBy employing a two‐stage continuous‐culture system, some of the more important physiological parameters involved in cellulose biosynthesis have been evaluated with an ultimate objective of designing an optimally controlled cellulose process. The two‐stage continuous‐culture system was run for a period of 1350 hr with Trichoderma reesei strain MCG‐77. The temperature and pH were controlled at 32°C and pH 4.5 for the first stage (growth) and 28°C and pH 3.5 for the second stage (enzyme production). Lactose was the only carbon source for the both stages. The ratio of specific uptake rate of carbon to that of nitrogen, Q(C)/Q(N), that supported good cell growth ranged from 11 to 15, and the ratio for maximum specific enzyme productivity ranged from 5 to 13. The maintenance coefficients determined for oxygen, MO, and for carbon source, MC, are 0.85 mmol O2/g biomass/hr and 0.14 mmol hexose/g biomass/hr, respectively. The yield constants determined are: YX/O = 32.3 g biomass/mol O2, YX/C = 1.1 g biomass/g C or YX/C = 0.44 g biomass/g hexose, YX/N = 12.5 g biomass/g nitrogen for the cell growth stage, and YX/N = 16.6 g biomass/g nitrogen for the enzyme production stage. Enzyme was produced only in the second stage. Volumetric and specific enzyme productivities obtained were 90 IU/liter/hr and 8 IU/g biomass/hr, respectively. The maximum specific enzyme productivity observed was 14.8 IU/g biomass/hr. The optimal dilution rate in the second stage that corresponded to the maximum enzyme productivity was 0.026 ∼ 0.028 hr−1, and the specific growth rate in the second stage that supported maximum specific enzyme productivity was equal to or slightly less than zero.
Alternate method of calculating the free‐energy change accompanying the growth of Saccharomyces cervisiae (Hansen) on three substrates
Authors: Battley E. H. 
Published: December 2004

AbstractA methods is described for determining the free energy of formation of the cells of Saccharomyces cerevisiae (Hansen) that are formed as the result of anaerobic growth on glucose, and aerobic growth on glucose and enthanol. The method is based on the direct relationship that exists between the enthalpy changes and the free‐energy changes that accompany the oxidation of 1g cellular material formed during these growth reactions and the degree of reduction of the same material. When the results of these calculations are used together with the free energies of formation of the reactions and of other products of a given growth reaction, it becomes possible to calculate the free‐ energy change accompanying this reaction. These free‐energy changes are in excellent agreement with those calculated by another methods based on the hypothesis that free‐energy change accompanying the conversion of the substrate plus other reactions into cellular material plus other products is equal to Zero.
Continuous deacetylation of cephalosporins
Authors: Konecny Jan , Sieber M. 
Published: December 2004

AbstractContinuous deacetylation of cephalosporin C, 7‐aminocephalosporanic acid, and of 2‐methoxyethyl acetate in packed beds of an immobilized esterase is described by simple empirical equations relating conversion to space velocity and temperature. The choice of process conditions is discussed in relation to the effects of temperature on column efficiency, column life, growth of microbial contaminants, and the rates of thermal decomposition of the substrates. At the preferred temperature of 10°C columns were operated continuously for one month with only small losses in efficiency.
Interspecific interactions in a methane‐utilizing mixed culture
Authors: Lamb S. C. , Garver J. C. 
Published: December 2004

AbstractA two‐member methane‐utilizing mixed culture of bacteria, formed by combining two pure cultures isolated from a naturally occurring methane‐utilizing mixed culture, was studied in continuous culture. From the nutritional requirements and substrate ranges of the pure cultures, a mechanism for the interspecific interactions occurring in the mixed culture was proposed. Product formation kinetics were determined in continuous culture for each product involved in the proposed mechanism. From this proposed mechanism a mathematical model was derived based on simple material balance equations around a single‐stage chemostat. The steady‐state predictions of this model were compared to experimental results obtained from continuous‐culture experiments with the two‐member methane‐utilizing mixed culture. Interspecific interactions occurring in two‐member methanol‐utilizing and three‐member methane‐utilizing mixed cultures have also been discussed.
Kinetic study of a hollow‐fiber enzyme reactor
Authors: Kitano Hiromi , Yoshijima Shigemi , Ise Norio 
Published: December 2004

AbstractEnzymes, such as urease and uricase, were entrapped in three kinds of hollow fibers. The apparent Michaelis–Menten constants Km(app) obtained for these enzyme reactors were always larger than Km of free enzyme because of the permeation resistance of substrate across the hollow‐fiber membrane. Km(app) increased with increasing degree of permeation resistance across the membrane by the increase in enzyme concentration. The half‐life of the entrapped urease in the continuous reaction system was 60–80% of that of free enzyme. Activation energies of hollow‐fiber enzyme reactors were always smaller than that of the free enzyme, because the activation energy of permeation was smaller than that of the enzyme reaction.
Regulatory aspects of bakers' yeast metabolism in aerobic fed‐batch cultures
Authors: Woehrer W. , Roehr M. 
Published: December 2004

AbstractA highly instrumented computer‐coupled bioreactor is used to investigate metabolic changes of Saccharomyces cerevisiae in aerobic fed‐batch systems which are generally applied in bankers' yeast manufacture. The four types of metabolism (oxidation of glucose, aerobic fermentation, oxidation of glucose and ethanol, and oxidation of ethanol) appearing in such systems are characterized by four significant fermentation parameters: Respiratory quotient (RQ), glucose uptake rate (Qg), ethanol turnover rate (QEtOH), and growth yield on glucose (Yg). Below the critical glucose concentration glucose and ethanol are utilized simultaneously. The shift from aerobic fermentation to nondiauxic growth on glucose and ethanol is not only dependent on glucose concentration. but also on the precultivation on cells. The uptake of ethanol is controlled by the glucose supply except in the case when ethanol is limiting; the oxygen uptake rate (Qo2), however, is unaffected by the ratio of Qg and QEtOH. Critical glucose concentration is not a constant value for a particular strain, but varies corresponding to the nutritional state of the cells.
Stability of immobilized α‐chymotrypsin
Authors: Kawamura Yasuko , Nakanishi Kazuhiro , Matsuno Ryuichi , Kamikubo Tadashi 
Published: December 2004

AbstractThe thermal of free and immobilized α‐chymotrypsin was investigated experimentally and theoretically. The inactivation process of free α‐chymotrypsin was analyzed with a kinetic model which included a first‐ order reaction process and autolysis. The effects of ionic strength, Ca2+ concentration, and temperature are discussed here in terms of the estimated kinetic parameters included in this model. The inactivation process of α‐chymotrypsin immobilized onto various supports by several methods was investigated. The Contribution of thermal denaturation and autolysis to the inactivation depended upon the method of immobilization. To interpret quantitatively the non‐first‐order thermal denaturation process of the immobilized enzyme, a model in which the heterogeneity of the immobilized enzyme was taken into account is proposed.
Maximum production in a bakers' yeast fed‐batch culture by a tubing method
Authors: Dairaku Kazuo , Yamasaki Yoshihiko , Kuki Kazuo , Shioya Suteaki , Takamatsu Takeichiro 
Published: December 2004

AbstractA feedback control system of the glucose feed rate in a bakers' yeast fed‐batch culture was developed by keeping the ethanol concentration constant. A PID controller and on–off controller were applied and discussed with the aid of the porous Teflon tubing method. Experimental results showed the effectiveness of the control system for avoiding the glucose effect and glucose starvation. It was shown that the feedback control system developed hare could achieve a maximum specific growth rate of 0.3 h−1 or a maximum cell yield of 0.5 g cell/g glucose in the fedhyphen;batch culture.
Immobilization of amyloglucosidase on alkylamine derivatives of metal‐link‐activated inorganic supports
Authors: Cabral J. M. S. , Novais J. M. , Cardoso J. P. 
Published: December 2004

AbstractA new process to couple amyloglucosidase (AG) to inorganic supports is described. The technique consists in activating the support with a transition metal salt according to the metal‐link method and subsequent amination and linkage of the alkylamine derivative using glutaraldehyde. The various parameters susceptible of influencing the properties of the immobilized enzyme (IME) preparation are investigated. The best result are obtained when 100 mg of 1000‐Å controlled porous glass (CPG) are treated with 45 mg of TiCl4 and the activated carrier aminated using a 10‐g/L solution of hexamethylenediamine (HMDA) in carbon tetrachloride (10 Ml/100 mg). Preparation obtained according to the process here described show operational stabilities much superior to those of AG immobilized on the same support by the traditional metal‐link method or its variations. The mechanism involved in the preparation of the amino derivative of CPG is proposed.
Pollution control of swine manure and straw by conversion to Chaetomium cellulolyticum SCP feed
Authors: Moo‐Young M. , Chahal D. S. , Stickney B. 
Published: December 2004

AbstractSwine manure has a very high pollution potential and obnoxious odor. Large farms particularly are confronted with a manure disposal problem since environmentally acceptable solutions are now required by government regulations. Swine manure was found to be a good source of supplementary nutrients to ferment wheat straw into single‐cell protein (SCP) with Chaetomium cellulolyticum when 0.13g (NH4)2SO4/g solid was used as an additional source of N. In batch fermentations, inhibitory effects, possibly due to soluble released from the straw during alkali or acid pretreatment, were overcome by starting the fermentation at about pH 7.0 and then reducing it to 5.0 during growth. An overall protein productivity of up to 66 mg/L h was obtained from a slurry mixture of 1% w/v solids of manure and straw. This compares favorably with 99 mg/L h when manure was fermented with glucose instead of straw as the main carbon source. A high protein productivity of 200 mg/L h was obtained from a slurry mixture containing anaerobically prefermented swine manure liquor and 1.5% w/v solids from straw. The final products of the manure and straw fermentations contained 25–30% DW crude protein and 6–20% DW cellulose and the materials were free of the original obnoxious odor and undesirable microbial contamination.
Application of porous teflon tubing method to automatic fed‐batch culture of microorganisms II. Automatic constant‐value control of fed substrate (ethanol) concentration in semibatch culture of yeast
Authors: Yamané Tsuneo , Matsuda Morio , Sada Eizo 
Published: December 2004

AbstractAn automatic feedback control system incorporating a porous Teflon tubing sensor was developed and a strain of yeast was cultivated semibatchwise in mineral salt medium by feeding pure ethanol as the sole carbon source. In the control system, The ethanol concentration was continuously measured by the porous Teflon tubing sensor combined with a flame ionization detector, and its output signals were furnished to an automatic feed controller which controlled an ethanol feed pump so that deviations from the set level of ethanol concentration might be corrected. The controller was constructed on the basis of proportional‐differential negative feedback control of which the proportional sensitivity and differentiation constants were estimated from the dynamic mass balance of ethanol. Precise measurement of temperature and compensation of the detector output signals for temperature fluctuations of culture broth were necessary to achieve good control. Cultivation experiments were carried out with three levels of concentrations: 102, 103, and 104 ppm. The relative deviations of the concentrations were less than ±0.5% for the 103‐ and 104‐ ppm levels but a little offset arose for the 102‐ppm levels. The growth of cells was at first exponential and then almost linear when the dissolved oxygen concentration dropped considerably.
Optimal design of airlift fermenters
Authors: Moresi Mauro 
Published: December 2004

AbstractIn this article a modeling of a draft‐tube airlift fermentor (ALF) based on perfect backmixing of liquid and plugflow for gas bubbles has been carried out to optimize the design and operation of fermentation units at different working capacities. With reference to a whey fermentation by yeasts the economic optimization has led to a slim ALF with an aspect ration of about 15. As far as power expended per unit of oxygen transfer is concerned, the responses of the model are highly influenced by kLa However, a safer use of the model has been suggested in order to assess the feasibility of the fermentation process under study.
A new sensor, the “filtration probe,” for quantitative characterization of the penicillin fermentation. I. Mycelial morphology and culture activity
Authors: Nestaas Eirik , Wang Daniel I. C. 
Published: December 2004

AbstractIn this article the filtration resistance of fungal (Penicillium) mycelia is shown to be quantitatively related to the morphology of the cells. On this basis, it was possible to determine the intracellular volume by simple filtration measurements. Since the dry weight of the cells can also be measured, a morphological variable‐the “hyphae density” (dry weight hyphae/volume hyphae)‐can be quantified. This variable typically is measured to have values in the range of 0.35–0.20 g/cm3; the lower values represent the final stages of the fermentation. It can be shown that this loss of cell material during fermentation is limited to cytoplasmic components, and that most (70%) of the components which disappear are proteins. Concurrent with and linearly related to this loss of proteins, the culture activity in terms of both cell maintenance energy (respiration activity) and penicillin synthesis also decreased. The hyphae density measured by filtration is therefore a direct measure of the metabolic potential of the organism.
A new sensor, the “filtration probe,” for quantitative characterization of the penicillin fermentation. II. The monitor of mycelial growth
Authors: Nestaas Erik , Wang Daniel I. C. , Suzuki Hiroaki , Evans Lawrence B. 
Published: December 2004

AbstractBiomass concentration during penicillin production can be estimated rapidly and with reasonable accuracy using the “filtration probe.” The basis for the measurement is the volume of the filter cake which, in contrast to the conventional “packed‐cell volume” measured by centrifugation, is only moderately affected by the morphology of the mycelia. The influence of the mycelial morphology on the specific filter cake volume [ υ (cm3 cake/g dry cells)] can additionally, to a large extent, be predicted from the (specific) filtration resistance of the broth. During the rapid (exponential) growth period, the specific cake volume is, however, more variable and typically exhibits a transient maximum value. The presence of such a maximum can be explained by a simple model for exponential growth of single mycelial particles. this model is based upon conventional kinetics for hyphae elongation and branching and applies well to experimental data (filtration behavior as well as microscopic studies) provided hyphae fragmentation is negligible (i.e., at high growth rates, μ ≅ μmax).