bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production of glycerol by hansenula anomala
Authors: Parekh S. R. , Pandey N. K. 
Published: December 2004

AbstractProduction of glycerol by Hansenula anomala in molasses–corn steep liquor based media was studied. The accumulation and yield of glycerol was dependent on the medium composition and aeration rate; pH control did not affect the yield. Intermittent addition of sugar during fermentation resulted in significant increase in production of glycerol.
An automatic method for on‐line estimation of the photosynthetic rate in open algal ponds
Authors: Ben‐Yaakov Sam , Guterman Hugo , Vonshak Avigad , Richmond Amos 
Published: December 2004

AbstractAn analytical model for dissolved oxygen concentration in an algal minipond was used to develop a new method for estimating, on‐line, the net O2 production rate (OPR) of the biological process. The method was tested experimentally and was found to provide crucial information on the vitality of the biological process and to provide an early warning of a possible forthcoming collapse of the ecosystern. It is suggested that the newly developed model and measurement method could provide investigators with useful tools for optimization of algal cultivation in the laboratory and plant.
Comparisons between cellulase production by Aspergillus fumigatus in agitated vessels and in an air‐lift fermentor
Authors: Wase D. A. John , McManamey William J. , Raymahasay Sugat , Vaid Aloke K. 
Published: December 2004

AbstractAspergillus fumigatus was cultured in disc‐turbine‐agitated vessels and in an air‐lift fermentor. In the agitated vessels the yield of cellulase was reduced when the agitation rate was increased, although extracellular protein levels rose. The enzyme complex itself was shown to be exceptionally stable under conditions similar to those in the agitated vessels, so probably shear damage to the mycelium had occurred, liberating intracellular contents. These appeared to contain an inhibitor that could be removed by fabricated inorganic protein absorbents, such as kieselguhr and alumina. However, the inhibitor was not likely to be protease, since only relatively low levels could be detected and its identity has not been established. The use of an air‐lift fermentor avoided the shear effects due to use of the disc turbine agitator in the conventional fermentors, and yields of enzyme were then found to increase by about 20%, maximum yields being obtained at maximum KLa values.
A growth model for the continuous microbiological leaching of a zinc sulfide concentrate by Thiobacillus ferrooxidans
Authors: Sanmugasunderam V. , Branion R. M. R. , Duncan D. W. 
Published: December 2004

AbstractThe leaching of a zinc sulfide concentrate by Thiobacillus ferrooxidans was investigated in continuous stirred tank reactors. A mathematical model for the growth of T. ferrooxidans on this solid substrate is presented and tested. Experimental leaching studies were done using two reactors in series with and without recycle of solids from the outlet of the first reactor back to its inlet. The proposed model fits the authors' experimental data well. However, comparison of the parameters calculated with those calculated from the data of others showed that a wide variation can exist; thus, the parameters seem to depend on the nature of the substrate. The area occupied on the sulfide surface by a bacterium was found to be 5.4 μm2. The calculated maximum specific growth rates ranged from 0.20 to 0.31 h−1, and these values were dependent on whether they were observed in the first or second of the two reactors in series.
Invertase activity of intact cells of Saccharomyces cerevisiae growing on sugar cane molasses. I. Steady‐state continuous culture tests
Authors: Vitolo Michele , Vairo Marina L. R. , Borzani Walter 
Published: December 2004

AbstractDuring the steady‐state continuous culture of Saccharomyces cerevisiae on sugar cane blackstrap molasses under different experimental conditions, oscillatory variations of the invertase activity of the intact yeast cells were observed. The continuous morphological changes of the cells wall and of the periplasmic space affecting the interaction between invertase and sucrose molecules could be responsible by the observed oscillatory phenomena. The average invertase activity at the steady state is linearly correlated to the cell's growth rate.
Biological treatment specific for an industrial wastewater containing s‐triazines
Authors: Hogrefe W. , Grossenbacher H. , Cook A. M. , Hütter R. 
Published: December 2004

AbstractMixed cultures of bacteria grew in medium containing real s‐triazine wastes as nitrogen source. About 80% of the s‐triazine waste could be degraded as determined by HPLC and by measurements of dissolved nitrogen. The culture required an added carbon source in order to degrade s‐triazines. A temperature optimum near 40°C was observed and a salt concentration above about 4% markedly retarded growth and the degradation of s‐triazines. This system was examined as a biological treatment for wastes from syntheses of s‐triazines.
Acetate inhibition of Pseudomonas putida
Authors: Fieschko John , Humphrey Arthur E. 
Published: December 2004

AbstractTo study the effect of acetate inhibition on the parameters of yield and maintenance for bacterial growth, Pseudomonas putida ATCC 23467 was grown in a minimal salts medium with acetate as the sole carbon source with limiting and with excess quantities of urea in the feed medium. The behavior of the chemostat cultures under sole acetate limitation results in low residual acetate present in the fermentation broth. These cultures can be described satisfactorily using the equation qs = D/Yg + m, i.e., the acetate is consumed only for growth and maintenance,. Those cultures in which urea was limiting or where urea was present in large excess contained significant amounts of residual acetate in the broth. For these cultures it was necessary to add a third term for acetate inhibition to the above expression.
Cellulase production by trichoderma harzianum in static and mixed solid‐state fermentation reactors under nonaseptic conditions
Authors: Deschamps F. , Giuliano C. , Asther M. , Huet M. C. , Roussos S. 
Published: December 2004

AbstractCellulase production from lignocellulosic materials was studied in solid‐state cultivation by both static and mixed techniques under nonaseptic conditions. The effects of fermentation conditions, such as moisture content, pH, temperature, and aeration, on cellulase production by Trichoderma harzianum using a mixture of wheat straw (80%) and bran (20%) were investigated. With a moisture content of 74% and a pH of 5.8., 18 IU filter paper activity and 198 IU endoglucanase activity/g initial substrate content were obtained in 66 h. The extension from static column cultivation to stirred tank reactor of 65 L capacity gave similar yields of cellulase.
Membrane separation of protein precipitates: Unstirred batch studies
Authors: Devereux N. , Hoare M. , Dunnill P. 
Published: December 2004

AbstractThe study examines the use of ultrafiltration and microfiltration membranes for concentrating isoelectric soya protein. Experiments with an unstirred batch cell indicate that the flux is limited by the protein which remains in solution after precipitation of the major proportion. The porosityof the precipitate cake formed is shown to be a second important factor. A significant improvement in flux can be obtained by using membranes which permit passage of the soluble protein and by increasing the precipitate particle size. The results are shown to be within the range predicted theoretically by the two limiting cases of a particulate model and a soluble protein model.
Ethanol fermentation by ionically adsorbed Zymomomas mobilis: Environmental effects on cell immobilization
Authors: Bar Raphael , Gainer John L. , Kirwan Donald J. 
Published: December 2004

AbstractBatch ethanol fermentation by cells of Zymomomas mobilis ATCC 29191, ionically adsorbed on a DEAE‐cellulose ion exchanger, was investigated in a stirred fermentor. Adsorption isotherms in different media were determined and used to interpret the effects of the environment on cell immobilization. Other factors affecting cell immobilization during an actual fermentation were studied. Mechanical agitation was found to cause detachment of cells from the ion exchange particles. The results suggest that the amount of cells adsorbed during a fermentation process is different from that found from adsorption isotherm data. Consequently, application of equilibrium adsorption data to actual fermentations should be done with caution.
Growth of the extreme thermophile Sulfolobus acidocaldarius in a hyperbaric helium bioreactor
Authors: Sturm F. J. , Hurwitz S. A. , Deming J. W. , Kelly R. M. 
Published: December 2004

AbstractThe relationship between pressure and temperature as it affects microbial growth and metabolism has been examined only for a limited number of bacterial species. Because many newly‐discovered, extremely thermophilic bacteria have been isolated from pressurized environments, this relationship merits closer scrutiny. In this study, the extremely thermophilic bacterium, Sulfolobus acidocaldarius, was cultured successfully in a hyperbaric chamber containing helium and air enriched with 5% carbon dioxide. Over a pressure range of approximately 1–120 bar and a temperature range of 67–80°C, growth was achieved in a heterotrophic medium with the air mixture at partial pressures up to 3.5 bar. Helium was used to obtain the final, desired incubation pressure. No significant growth was noted above 80°C over the same range of hyperbaric pressures, or at 70°C when pressure was applied hydrostatically. Growth experiments conducted under hyperbaric conditions may provide a means to study these bacteria under simulated in situ conditions and simultaneously avoid the complications associated with hydrostatic experiments. Results indicate that hyperbaric helium bioreactors will be important in the study of extremely thermophilic bacteria that are isolated from pressurized environments.
Production of ethanol by immobilized Saccharomyces bayanus in an extractive fermentation system
Authors: Barros M. R. Aires , Cabral J. M. S. , Novais J. M. 
Published: December 2004

AbstractAn extractive fermentation system using immobilized yeast cells was developed to study the ethanol production at high sugar concentrations. Organic acids were used as extracting solvents of ethanol and their toxicity was tested in free and k‐carrageenan entrapped cell preparations. Immobilization seems to protect cells against solvent toxicity, when long‐chain organic acids, e.g., oleic acid, were used, probably due to steric and diffusional limitations, the free cells not being viable at high oleic acid concentrations. The entrapped cells also present a higher metabolic activity than their free counterparts at high glucose concentrations. A solution of 300 g/L of glucose was totally fermented by the immobilized yeast cells, which when free cannot normally convert more than 200 g/L. In situ recovery of ethanol by oleic acid in a batch immobilized cell system led to higher ethanol productivities and to the fermentation of 400 g/L, when an oleic acid/medium ratio of 5 was used.
Controlled expression and purification of human immune interferon from high‐cell‐density fermentations of Saccharomyces cerevisiae
Authors: Fieschko John C. , Egan Kevin M. , Ritch Thomas , Koski Raymond A. , Jones Matthew , Bitter Grant A. 
Published: December 2004

AbstractConditions for high‐cell‐density fermentations of Saccharomyces cerevisiae strains producing recombinant‐DNA‐derived proteins were established. Strains producing human immune interferon (IFN‐γ) from the constitutive PGK promoter failed to grow to high cell densities and exhibited low plasmid stability. Regulated expression of IFN‐γ was obtained in similar strains by employing a hybrid yeast GPD promoter that was subject to carbon source regulation due to the presence of regulatory DNA sequences from the yeast GAL 1,10 intergenic region. IFN‐γ expression programmed by this vector was low during growth on glucose and was induced by galactose. Previously defined fermentation conditions employing glucose as a carbon source were applied to this strain, resulting in high ceil densities with higher plasmid stability. Various methods of galactose induction of IFN‐γ expression in high‐cell‐density fermentations were investigated. Optimal conditions resulted in a 2000‐fold induction and production of 2 g IFN‐γ/L fermentation culture.
Characteristics of draft tube gas–liquid–solid fluidized‐bed bioreactor with immobilized living cells for phenol degradation
Authors: Fan Liang‐Shih , Fujie Koichi , Long Teng‐Rui , Tang W.‐T. 
Published: December 2004

AbstractBiological phenol degradation in a draft tube gas‐liquid‐solid fluidized bed (DTFB) bioreactor containing a mixed culture immobilized on spherical activated carbon particles was investigated. The characteristics of biofilms including the biofilm dry density and thickness, the volumetric oxygen mass transfer coefficient, and the phenol removal rates under different operating conditions in the DTFB were evaluated. A phenol degradation rate as high as 18 kg/m3‐day with an effluent phenol concentration less than 1 g/m3 was achieved, signifying the high treatment efficiency of using a DTFB.
Purification and partial characterization of a cellodextrin glucohydrolase (β‐glucosidase) from Trichoderma reesei strain QM 9414
Authors: Schmid G. , Wandrey Ch. 
Published: December 2004

AbstractA β‐glucosidase (E.C. 3.2.1.21) was isolated from the culture filtrate of fungus Trichoderma reesei QM 9414 grown in continuous culture with biomass retention. The crude extracellular enzyme preparation was fractionated by a three‐step purification procedure [chromatography on Fractogel HW‐55 (S) and Bio‐Gel A 0.5 plus final preparative isoelectric focusing] to yield three β‐glucosidases with isoelectric points at pH 8.4, 8.0, and 7.4. Only one enzyme (pi 8.4) met the stringent criterion of being homogeneous according to titration curve analysis. This enzyme was then characterized not to be a glycoprotein, although the native protein contained 35% carbohydrate (as glucose). It was found to have an apparent molar mass of 7 × 104 g/mol (SDS‐PAGE), exhibited its optimum activity towards cellobiose at pH 4.5 and 70°C (30 min test), and lost less than 3% activity at 50°C over a period of 7 h. The KM values towards cellobiose and p‐nitrophenyl‐β‐D‐glucopyranoside were determined to be 0.5mM and 0.3mM, respectively. The enzyme hydrolyzed cellodextrins (cellotriose to cellooctaose) by sequentially splitting off glucose units from the nonreducing end of the oligomers. The extent of the observed transfer reactions varied with the initial substrate concentration. No enzyme activity towards microcrystalline cellulose or carboxymethylcellulose could be detected. The classification of the enzyme as β‐glucosidase or exo‐β‐1,4‐glucan glucohydrolase is discussed with respect to the exhibited hydrolytic activities.
Growth of free and attached Thiobacillus ferrooxidans in ore suspension
Authors: Espejo Romilio T. , Ruiz Paulina 
Published: December 2004

AbstractThe growth of Thiobacillus ferrooxidans in a copper‐containing ore suspension incubated in shake flasks was studied by determining the number of colony‐forming units both in solution and attached to ore particles. The amounts of iron and copper released from the ore under experimental conditions were also determined. The total ferrous iron either released from the minerals or generated by reduction of the ferric iron in the minerals could account for the observed growth of bacteria in solution. Only a small fraction of the total colony‐forming units—about 500 per mg ore—was found to be associated with the ore particles throughout the experiments. However, the rapid development of these colonies when ore particles were plated suggested that they were produced by a number of bacteria associated with each ore particle. Accordingly, when the amount of bacteria attached to ore particles was determined by monitoring the formation of ferric iron in the plates, the percentage of the total activity associated with attached bacteria was found to be between 1 and 10%.
Coaggregate of trypsin and chymotrypsin
Authors: Rajput Yudhishthir S. , Gupta Munishwar N. 
Published: December 2004

AbstractThe method of chemical aggregation of enzymes has the advantage of yielding an immobilized enzyme preparation wherein reactor volume can be significantly reduced because of the absence of an inert carrier. A coaggregate of trypsin and chymotrypsin formed by extensive cross‐linking with glutaraldehyde is described. A significant property of this aggregate is the reduced autolysis of the trypsin component of the coaggregate.
Computer aided analysis for biosensing and screening
Authors: Li Xiang‐Ming , Liang Bernard S. , Wang Henry Y. 
Published: December 2004

AbstractBiosensors with animal and microbial cells immobilized close to the tip of a membrane electrode have been developed for chemical and drug testing. Our experimental results show that biosensors can be used for drug screening and to provide useful information about various cell‐chemical interactions. A computer aided analysis (CAA) software package is being developed here using the biosensor for various screening purposes. This software package enables us to use a computer to analyze the biosensor dynamic responses. Computer simulation and parameter estimation techniques are used to select the best model and to describe the biochemical and pharmacologic effects of various chemicals and drugs on different cell lines.
Optimization of biphasic growth of Saccharomyces carlsbergensis in fed‐batch culture
Authors: Pyun Yu Ryang , Modak Jayant M. , Chang Yong K. , Lim Henry C. 
Published: December 2004

AbstractThe optimal glucose feeding policy for the fed‐batch culture of Saccharomyces carlsbergensis is presented. The biphasic nature of growth results in a singular feed rate policy that is unique to this organism. When the operating cost is high, the reduction in operating time forces the cells to utilize both glucose and ethanol toward the end of fermentation time and results in a decreasing rate of glucose addition, unlike the normally observed in creasing feed rate. The optimal feeding policy depends heavily on the initial conditions and is highly sensitive to changes in kinetic parameters. A semiempirical scheme for feedback optimization is suggested for the fed‐batch yeast culture.
Relation between stabilization and rigidification of the three‐dimensional structure of an enzyme
Authors: Germain P. , Slagmolen T. , Crichton R. R. 
Published: December 2004

AbstractPurified cellobiase was coupled to periodate‐oxidized dextran by reductive alkylation using sodium cyanoborohydride, sodium borohydride, and dimethylaminoborane for various reaction times. The thermal stability of the different conjugates obtained was studied and correlated to the number of links introduced between the enzyme and the soluble support. We observe that resistance to heat inactivation increases as a function of the number of modified lysines. Sodium cyanoborohydride was the most effective reducing agent. After 24 h reaction, the modification of 92% of the lysines gave a cellobiase–dextran conjugate that is a most stable enzyme. We conclude that the thermal stability observed for the chemically modified enzyme results from the rigidification of the three‐dimensional structure of the protein. This rigidification increases with the number of links introduced between the enzyme and the polysaccharide. We also observe that chemical modification leads to a heterogeneous population of stabilized enzymes. Because of this heterogeneous population, it is necessary to develop a mathematical model of the kinetics of enzyme inactivation.
Reversibility and competition in the adsorption of Trichoderma reesei cellulase components
Authors: Kyriacou Andreas , Neufeld Ronald J. , MacKenzie C. Roger 
Published: December 2004

AbstractAdsorption reversibility and competition between fractionated components of the Trichoderma reesei cellulase system were studied. Specific endoglucanase (EGI), nonspecific endoglucanases (EGII, EGIII), and cellobio‐hydrolase (CBHI) were previously grouped according to their hydrolytic function. At 5°C, direct evidence of exchange between adsorbed and free enzyme was obtained for each component using [3H] and [14C] radiolabeled tracers. No release of bound enzymes was detected upon dilution of the free enzyme solution. In simultaneous adsorption of enzyme pairs, CBHI was shown to predominate adsorption. Endoglucanase EGI was preferentially adsorbed over EGII and EGIII. Sequential adsorption studies have shown that interaction between enzyme components largely determines the degree of their adsorption. Evidence suggests that both common and distinct adsorption sites exist and that their occupation depends on which components are involved. Predominance in adsorption by any one of the enzyme components is decreased at 50°C. Light microscopy and monitoring of sugar production during cellulose hydrolysis provided evidence that reduction in the ionic strength decreases the adsorption predominance of CBHI and enhances the synergism between the cellulase components.
Control of mixed microbial cultures via specific cell adhesion
Authors: Roos Joseph W. , Hjortso Martin A. 
Published: December 2004

AbstractA new method for manipulating the steady‐state behavior of a mixed culture is introduced. The method makes use of differences in adherence properties between competing populations to maintain a desired population ratio. The very specific nature of some ligand‐to‐cell interactions allows precise manipulation of even closely related populations. The control method is illustrated by analysis and simulations of models of a competitive mixed culture and a culture of an unstable recombinant organism. In both cases, retention of the disadvantaged population via cell adhesion results in creation of a stable coexistence steady state over a range of operating conditions.
Oscillatory behavior of population density in continuous culture of genetic‐engineered Bacillus stearothermophilus
Authors: Koizumi Jun‐ichi , Aiba Shuichi 
Published: December 2004

AbstractAn oscillatory behavior in population density was observed when a transformant of Bacillus stearothermophilus carrying a rocombinant plasmid pZAM26 was cultivated continuously in a well‐stirred reactor vessel at a fixed dilution rato. Among the transformant cells that were subjected to the continuous culture, the fraction of cells harboring p2AM26 was found to be as high as 0.98–1.00 despite the emergence of the oscillation. Cells whose plasmids underwent rearrangement of DMA in terms of structural change could not be found throughout. With reference to this observation, the dynamics of the genetic‐engineered bacterium was analyzed within the category of both the linearized stability principle and the bifurcation theory. It was concluded that Hopf bifurcation was most probable to account for the experimental oscillation.