bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrolysis of butteroil by immobilized lipase using a hollow‐fiber reactor: Part III. Multiresponse kinetic studies
Authors: Malcata F. Xavier , Hill Charles G. , Amundson Clyde H. 
Published: December 2004

AbstractA lipase from Aspergillus niger immobilized by adsorption on microporous, polypropylene hollow fibers was used to effect the continuous hydrolysis of the glycerides of butter oil at 40°C and pH 7.0. The effluent concentrations of 10 different free fatty acid products were measured by highperformancee liquid chromatography (HPLC). Multiresponse nonlinear regression methods were used to fit the data to a multisubstrate rate expression derived from a Ping Pong Bi Bi mechanism in which the rate‐controlling step is deacylation of the lipase. Thermal deactivation of the enzyme was also included in the mathematical model of reactor performance. A postulated normal distribution of vmax with respect to the chain length of the fatty acid (with an additive correction for the degree of unsaturation) was tested for statistical significance. The model is useful for predicting the free fatty acid profile of the lipolyzed butteroil product over a wide range of flow rates.
Hydrolysis of butteroil by immobilized lipase using a hollow‐fiber reactor: IV. Effects of temperature
Authors: Malcata F. Xavier , Hill Charles G. , Amundson Clyde H. 
Published: December 2004

AbstractA lipase from Aspergillus niger, immobilized by adsorption on microporous polypropylene hollow fibers, was used to effect the hydrolysis of the glycerides of melted butterfat at pH. 7.0 at 40, 50, 55, and 60°C. Mcllvane buffer was pumped upward through the lumen, and melted butterfat was pumped upward through the shell side of a hollow fiber reactor. Nonlinear regression methods were employed to determine the kinetic parameters of models based on combinations of three nested rate expressions for the hydrolysis reaction with three nested rate expressions for thermal deactivation of the enzyme. A rate expression containing four lumped parameters is sufficient to model the release of free fatty acids as a function of reactor space time and time elapsed after immobilization. Nonlinear regression methods were also employed in global fits of the data to rate expressions containing an explicit dependence on temperature. For the reaction conditions used in this research, a 14‐parameter rate expression is necessary to accurately model the overall release of free fatty acids as a continuous function of the absolute temperature, initial substrate concentrations, reactor space time, and time elapsed after immobilization of the lipase.
On‐line fluorescence‐monitoring of the methanogenic fermentation
Authors: Peck Michael W. , Chynoweth David P. 
Published: December 2004

AbstractOn‐line in situ fluorescence measurements of the methanogenic fermentation were conducted with reactors receiving either glucose or a mixture of volatile fatty acids as the substrate. The reactors were perturbed from steady‐state conditions in order to assess the response of fluorescencemonitoring probes. Two fluorescence‐monitoring probes were evaluated over a period of 8 months; they performed in a consistent manner, and their response was not significantly affected by the changes in pH and redox potential encountered during routine reactor operation. A commercially available probe, designed to measure NAD(P)H, demonstrated particular promise for detecting imbalance caused by the entry of air, inhibitor addition and was capable of distinguishing between different substrates. This fluorescence‐monitoring probe detected imbalance more rapidly than other on‐line measurements such as pH, Eh, or gas production, or off‐line measurements such as volatile fatty acid concentration or gas composition. An experimental fluorescence‐monitoring probe, designed to measure coenzyme F420, also showed some promise in this regard. The response of the fluorescence‐monitoring probes also revealed details of the metabolic routes in the reactors and the probes represent a useful research tool. For example, a failure to observe the characteristic response of the NAD(P)H‐monitoring probe to formate addition during the metabolism of acetate, propionate, or glucose strongly suggests that any formate liberated during their catabolism is degraded via a different route to exogenously added formate.
The effects of surface adsorption on the thermal stability of proteins
Authors: Steadman Bryan L. , Thompson Karen C. , Middaugh C. Russell , Matsuno Ken , Vrona Susan , Lawson Erlinda Q. , Lewis Randolph V. 
Published: December 2004

AbstractThe effect of surface adsorption on the structure and stability of proteins is a matter of increasing interest in biotechnology. Therefore, we have examined the effect of adsorption to silica on the thermal stability of 7 proteins employing differential scanning calorimetry (DSC) and front surface fluorescence (FSF) spectroscopy. In general, it was found that surface adsorption decreased the thermal stability of the bound protein. Using lysozyme for further studies, DSC, FSF, and FTIR spectroscopies, as well as enzymatic activity measurements, were used to explore the effect of decreasing surface apolarity on stability. It was observed that increasing surface apolarity produced decreasing stability and increasing structural alteration of the adsorbed protein.
Biosurfactants and aqueous two‐phase fermentation
Authors: Drouin C. M. , Cooper D. G. 
Published: December 2004

AbstractThe partition of surfactants and a biosurfactant‐producing microorganism was studied in polyethylene glycol and dextran aqueous two‐phase systems. In the presence of sodium phosphate, surfactants distributed themselves according to charge. Cationic surfactants preferred the bottom phase, while anionic surfactants were attracted to the top phase. Incresing the phosphate molarity or the pH resulted in a more 1‐sided surfactant partitioning. Biosurfactant partitioning was weaker than synthetic surfactant partitioning due to the weaker effective charge and lack to strong specific affinity for any of the phase‐forming polymers. Bacillus Subtilis cells partitioned very storngly to the bottom phase. The bioscurfactant, surfactin, produced by this microorganism partitioned to the top phase. Batch fermentations were carried out in an aqueous 2‐phase system. Surfactin was produced in larger quanities in the 2‐phase fermentation than in the regular mineral salts medium.
Batch cultivation of Methylosinus trichosporium OB3b: II. Production of particulate methane monooxygenase
Authors: Park Sunghoon , Shah Nilesh N. , Taylor Robert T. , Droege Michael W. 
Published: December 2004

AbstractThe obligatory methanotroph, Methylosinus trichosporium OB3b, was studied to optimize the batch culture conditions for the formation of particulate methane monooxygenase (pMMO) in a nitrate minimal salts medium. The important medium components investigated were copper, carbon dioxide, and nitrate. The whole‐cell specific pMMO activity decreased sharply with increasing copper concentrations in the range of 10–40 μM and remained constant upon further increases of the copper concentration to 120 μM. The cell growth rate (μ), on the other hand, decreased over the entire range (10–120 μM) of copper concentrations tested. When pMMO was produced in a bioreactor with an optimal initial copper concentration of 10 μM, M. trichosporium OB3b exhibited a much faster overall growth rate and a higher whole‐cell propene epoxidation activity compared to our earlier study, in which soluble methane monooxygenase (sMMO) was produced with copper‐deficient medium. The addition of external carbon dioxide to the bioreactor culture eliminated an initial lag period in the cell growth. When the standard culture medium nitrate concentration (10 mM) was depleted, the pMMO activity, but not the growth rate, decreased rapidly. The whole‐cell specific pMMO activity could be maintained by subsequent supplementation of nitrate. A 4‐fold higher initial culture medium nitrate concentration of 40 mM, however, resulted in slower cell growth and lower pMMO activity. These observations demonstrate that, in addition to affecting the exclusive production of pMMO, copper also has an important previously unrecognized role in enhancing the growth rate of M. trichosporium OB3b. They also indicate that for the optimal batch production of pMMO with the minimal medium under study, nitrate should be supplied intermittently during the course of cultivation until other culture medium components become growth‐limiting.
Modeling particle transport by bubbles for performance guidelines in airlift fermentors
Authors: Snape J. B. , Thomas N. H. 
Published: December 2004

AbstractA calculation method has been developed to model the statistical transport of biological particles in bubble‐driven flows, with special reference to the biokinetics of environmental excursions experienced by individual cells, aggregated cells, or immobilization beads in airlift bioreactors. Interim developments on modeling the transport of such particles in concentric tube devices are reported. The calculation is driven by user‐prescribed global parameters for the bioreactor geometry, bulk air flow rate, and particle parameters (size and slip speed). The algorithm calls on empirical data correlations for void fraction, bulk liquid flow rate, and bubble sizes and slip speeds, optimally selected from a large bibliographic database. The Monte Carlo algorithm concentrates on simulating particle transport in the bubbly riser flows.The packaged family of correlations and calculations represents, in effect, an expert system augmented by a transport simulation suited to characterizing the biokinetic response of cells cultured in airlift bioreactors.
Development of a multienzyme reactor for dopamine synthesis: II. Reactor engineering and simulation
Authors: Anderson William A. , Moo‐Young Murray , Legge Raymond L. 
Published: December 2004

AbstractAspects of reaction engineering associated with multienzyme reactions have been studied in a system where dopamine is produced from catechol, pyruvate and ammonium by sequential enzymatic reactions catalyzed by tyrosine phenol lyase (TPL) and tyrosine decarboxylase (TDC). Microbial cells containing TPL activity (Erwinia herbicola) and TDC activity (Streptococcus faecalis) were coimmobilized in glutaraldehyde cross‐linked porcine gelatin beads with a mean diameter of 2.8 mm for use in the reactions. Measurement of the transport properties in the beads indicate that the gelatin matrix does not significantly increase the diffusion resistance and that dopamine partitions into the matrix (K = 2). A packed‐bed reactor containing the coimmobilized cell beads successfully produced dopamine, although with a low conversion. Using computer simultaneous it is shown that separate, sequential TPL and TDC, rather than simultaneous, reactions, would require smaller reactors overall for the same conversion. © 1992 John Wiley & Sons, Inc.
Studies on the isolation of penicillin acylase from Escherichia coli by aqueous two‐phase partitioning
Authors: Guan Yue , Wu Xing‐Yan , Treffry Timothy E. , Lilley Terence H. 
Published: December 2004

AbstractA method of enzyme release and aqueous two‐phase extraction is described for the separation of penicillin acylase from Escherichia coli cells. Butyl acetate, 12% (v/v), treatment combined with freeze–thawing gives up to 70% enzyme release. For polyethylene glycol (PEG) + phosphate two‐phase extraction systems the enzyme purity and yield were rather low. Modified PEG, including PEG–ampicillin, PEG–aniline, PEG–phosphate, and PEG–trimethylamine, were synthesized and used in aqueous two‐phase systems; PEG–trimethylamine is the most satisfactory. A system containing 12% (w/w) PEG4000, 8% (w/w) of which is PEG–trimethylamine, with 0.7M potasium phosphate at pH 7.2, resulted in the enzyme selective partition being greatly enhanced by charge directed effects. Possible mechanisms for the separation process are discussed. © 1992 John Wiley & Sons, Inc.
A structured dynamic model for the baculovirus infection process in insect‐cell reactor configurations
Authors: De Gooijer Cornelis D. , Koken Rick H. M. , Van Lier Frank L. J. , Kool Marcel , Vlak Just M. , Tramper Johannes 
Published: December 2004

AbstractA mathematical description of the infection of insect cells with baculovirus in a continuously operated reactor configuration is presented. The reactor configuration consists of one bioreactor in which insect cells (Spodoptera frugiperda) are grown followed by one or two bioreactors in which cells are infected by a baculovirs (Autographa californica nuclear polyhedrosis virus). It was demonstrated that the so‐called passage effect is responsible for the observed difference in run time between a configuration with one or with two infection vessels. Furthermore, a model is presented based on the hypothesis that the limited run time of series of continuously operated bioreactors is associated with the occurrence of a virus particle (so‐called virion) that is defective and has interfering properties. With the assumption that not all nonoccluded virions are capable of establishing a correct infection leading to new virus production, infection levels in continuously operated reactor configurations could be described well with the model. © 1992 John Wiley & Sons, Inc.
Treatment of metal‐contaminated water using bacterial sulfate reduction: Results from pilot‐scale reactors
Authors: Dvorak Darryl H. , Hedin Robert S. , Edenborn Harry M. , McIntire Pamela E. 
Published: December 2004

AbstractSimple anaerobic reactors were installed to treat metal‐contaminated water in an underground coal mine and at a smelting residues dump in Pennsylvania. The reactors consisted of barrels and tanks filled with spent mushroom compost, within which bacterial sulfate reduction became established. Concentrations of Al, Cd, Fe, Mn, Ni, and Zn were typically lowered by over 95% as contaminated water flowed through the reactors. Cadmium, Fe, Ni, and some Zn were retained as insoluble metal sulfides following their reaction with bacterially generated H2S. Aluminum, Mn, and some Zn hydrolyzed and were retained as insoluble hydroxides or carbonates. Reactor effluents were typically circumneutral in pH and contained net alkalinity. The principal sources of alkalinity in the reactors were bacterial sulfate reduction and limestone dissolution. This article examines the chemistry of the reactor systems and the opportunities for enhancing their metal‐retaining and alkalinity‐generating potential. © 1992 John Wiley & Sons, Inc.
Analysis of noise and bias in fermentation oxygen uptake rate data
Authors: Royce Patrick N. , Thornhill Nina F. 
Published: December 2004

AbstractThe calculation of many derived fermentation variables such as the respiratory quotient (RQ) and mass transfer coefficient (KLa) requires the differences between the molar percentages of oxygen and carbon dioxide in the fermentor inlet and exit gas, called the %OUR and %CER. Noise and bias in %CER data is of order that in the exit gas carbon dioxide analysis. However, the relative amount of noise in the %OUR is one to two orders of magnitude greater than the noise in the raw oxygen analyses because the %OUR is calculated as a small difference between two large quantities. The noise in the %OUR is white with a Gaussian amplitude probability distribution of absolute standard deviation 0.0145. A chi‐square filter of the %OUR data is shown to considerably improve the quality of the calculated RQ and KLa for a fermentation of Streptomyces clavuligerus. © 1992 John Wiley & Sons, Inc.
Overexpression of cloned genes using recombinant Escherichia coli regulated by a T7 promoter: I. Batch cultures and kinetic modeling
Authors: Miao Fudu , Kompala Dhinakar S. 
Published: December 2004

AbstractA novel Eschericha coli expression system directed by bacteriophage T7 RNA Polymerase utilized for overexpression of the cloned gene. The recombinant cell contains the plasmid with a bacteriophage promoter, the T7 promoter, to regulate the expression of the target gene. This promoter is recongnized only by T7 RNA polymerase, whose gene has been fused into the host chromosome and is under control of the lacUV5 promoter. Therefore, the target gene on the plasmid can be expressed only in the presence of T7 RNA polymerase, which is induced by isopropyl‐β‐D‐thiogalactopyranoside (IPTG). The batch cultures were performed to investigate the effect of induction on kinetics of cell growth and foreign protein formation and to determine the optimal induction strategy. It was observed that the specific growth rates of the recombinant cells dramatically decrease after induction, and that there is an optimal induction time for maximizing the accumulated intracellular foreign protein. This optimal induction time varies singificantly with inducer concentration. To better understand the optimal behavior, a lumped mechanistic model was constructed to analyze the induced cell growth and foreign protein formation rates. © 1992 John Wiley & Sons, Inc.
A structured model for simulation of cultures of the cyanobacterium Spirulina platensis in photobioreactors: II. Identification of kinetic parameters under light and mineral limitations
Authors: Cornet J. F. , Dussap C. G. , Cluzel P. , Dubertret G. 
Published: December 2004

AbstractA structured model for the culture of cyanobacteria in photobioreactors is developed on the basis of Schuster's approximations for radiative light transfer. This model is therefore limited to monodimensional geometries and kinetic aspects.Light‐harvesting pigments play a crucial role in defining the profile of radiative transfer inside the culture medium and in controlling the metabolism, particularly the metabolic deviations induced by mineral limitations. Modeling therefore requires the biomass to be divided into several compartments, among which the light‐harvesting compartment allows a working illuminated volume to be defined within the photobioreactor. This volume may change during batch cultures, largely decreasing as pigment concentration increases during growth but increasing as pigments are consumed during mineral limitation. This approach enables, in photobioreactors of simple parallelepipedic, geometries, kinetic parameters to be determined with high accuracy; this may then be extended to vessels of more complex geometries, such as cylindrical photobioreactors.The model is applied to controlled batch cultures of the cyanobacterium Spirulina platensis in parallelepipedic photobioreactors to assess its ability to predict the behavior of these microorganisms in conditions of light and mineral limitations. Results allowed the study of optimal operating condition for continuous cultures to be approached © 1992 John Wiley & Sons, Inc.
Effective extracellular production of Bacillus stearothermophilus esterase by pH‐stat modal fed‐batch culture of recombinant Bacillus brevis
Authors: Tulin Edgardo E. , Ueda Shunsaku , Yamagata Hideo , Udaka Shigezo , Yamane Tsuneo 
Published: December 2004

AbstractAn automated two‐component substrate feeding strategy with a pH‐stat modal fed‐batch culture using a high pH limit was developed to effectively porduce esterase from a hyperprotein exreting Bacillus brevis HPD31 harboring a plasmid pHSC131 which carries a Bacillus stearothermo philus esterase gene. First, the effect of single‐ and multi‐substrate feedings on the growth and activity of the excreted esterase was investigated. Then a two‐component (polypepton + glucose) feeding using different feed rates was studied. Highest activity of the excreted esterase (34 U/mL) was obtained when the concentrations of poly‐pepton and glucose in the nutrient feed solution were 250 and 41.60 g/L respectively. The absence and excessive amount of glucose in the nutrient feed solution was ineffective for the exracellular esterase formation because without glucose the increase in cell concentration was minimum while excessive amount of glucose favored cell growth at the expense of the esterase production. It is believed that the mechanism of enzyme excretion is growth dependent and that a higher cell growth of the host is in effect unfavorable for the enzyme production. The feed rate, automatically controlled by the direct signal of the pH change, at 0.30 mL/pulse was found optimum for the esterase production while lower (0.15 mL/pulse) and higher (0.67 mL/pulse) feed rates did not produce good results. The activity of the excreted esterase was increased more than eight times from 4 U/mL obtained in the conventional batch culture to 34 U/mL obtained in this study. The esterase productivity was likewise increased more than threefold. © 1992 John Wiley & Sons, Inc.
Advanced control of glutathione fermentation process
Authors: Sakato Kuniaki , Tanaka Hisao 
Published: December 2004

AbstractA study was performed to understand the fermentation process for production of glutathione fermentation (GSH) with an improved strain of baker's yeast. Simultaneous utilization of sugar and ethanol has been found to be a key factor in the industrial process to produce GSH using Saccharomyces cerevisiae KY6186. Based on this observation, the optimal sugar feed profile for the fed‐batch operation has been determined. A feedforward/feedback control system was developed to regulate the sugar feed rate so as to maximize GSH production yields. Using the feedforward/feedback control system and the on‐line data of oxygen and ethanol concentration in exhaust gas, the successful scaleup to the production level was accomplished. An average of 40% improvement of glutathione production compared to a conventionally programmed control of exponential fed‐batch operation was found in the new process. © 1992 John Wiley & Sons, Inc.
Activation of microcarrier‐attached lymphocytes in microgravity
Authors: Bechler B. , Cogoli A. , Cogoli‐Greuter M. , Müller O. , Hunzinger E. , Criswell S. B. 
Published: December 2004

AbstractA technology has been developed to achieve optimal attachment of adhesion‐independent lymphocytes to microcarrier beads. The activation of T‐lymphocytes by concanavalin A was tested under microgravity conditions in an experiment carried out in space during the first Spacelab Life Science Mission. Activation, measured as the synthesis of deoxyribonucleic acid (DNA) and the production of interferon‐gamma, more than doubled in attached lymphocytes in microgravity. The depression of the activation discovered in previous space experiments is due to an impairment not of the lymphocyte but of the macrophage function. The system described here may be useful for radiobiological investigations on the effect of high‐energy particles and for testing the efficiency of the immune system in humans during the long‐duration space flight planned in the future. The biotechnological significance of the increased lymphokine production in space remains to be assessed. © 1992 John Wiley & Sons, Inc.
Fragmentation of cellulose by the major Thermomonospora fusca cellulases, Trichoderma reesei CBHI, and their mixtures
Authors: Walker L. P. , Wilson D. B. , Irvin D. C. , McQuire C. , Price M. 
Published: December 2004

AbstractIn this study, the fragmentation activities of Thermomonospora fusca cellulases E2, E3, E5, Trichoderma reesei CBHI, and their mixtures were measured to study synergism in fragmentation. Fragmentation studies revealed that only two pure cellulases, T. fusca E2 and E5 had significant fragmentation activity. T. fusca E3 shows strong synergism in fragmentation both in the production of reducing sugars and in fragmentation with both T. fusca endoglucananses and with T. reesei CBHI. Most mixtures containing CBHI produced higher rates of fragmentation than comparable mixtures containing E3. The highest rate and extent of reducing sugar formation and the highest fragmentation activity were obtained with a mixture of E2, E3, and CBHI. © 1992 John Wiley & Sons, Inc.