bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental and mathematical modeling studies of protozoan predation on bacteria
Authors: Canale R. P. , Lustig T. D. , Kehrberger P. M. , Salo J. E. 
Published: December 2004

AbstractThe predation of bacteria by protozoan in both continuous and batch cultures was studied using experimental and modeling techniques. The predator organism was the ciliate, Tetrahymena pyriformis. The bacterium, Aerobacter aerogenes, served as the prey. Several batch growth responses were observed each initiated at a different nutrient level. Continuous cultures were conducted over a range of dilution rates. The models studied were partially successful in simulating the empirical data. Deviations between the model and the actual population behavior are discussed and possible explanations for the differences proposed.
Effects of polymer additives on fermentation parameters in a culture ofA. niger
Authors: Elmayergi H. , Scharer J. M. , Moo‐Young M. 
Published: December 2004

AbstractOf 24 different polymer and surfactant materials examined, a carboxypolymethylene (“Carbopol”) was found to cause enhancement of respiration rates in anAspergillus nigerculture by as much as 200%. Enhancement of other fermentation parameters, such as cellular growth and amylase production, was also observed.The enhancement effects of Carbopol were examined with clusters of spores and mold pellets. In the first case, it appears that the ionized carboxyl groups of Carbopol induced electrostatic repulsion among the spores thus initiating pulp growth with increased interfacial area of contact between the mold and the nutrient medium. In the second case, the Carbopol additive formed a thin film attached to the surface of the pellets which seemed to be responsible for an increased rate of potassium transport and, hence, fermentation yields. Additive utilization as substrate and physiological changes in the culture were not observed in these cases.It was also found that the probability of pellet formation, the size of pellets formed, and the number of spores per pellet can be correlated to the energy input to the fermentation system.
Mixed culture biooxidation of phenol. I. Determination of kinetic parameters
Authors: Pawlowsky U. , Howell J. A. 
Published: December 2004

AbstractA mixed culture derived from soil and activated sludge organisms was used to degrade phenol which was inhibitory to microorganisms at higher concentrations. The purpose of the experiments was to determine the kinetic parameters governing growth of the organisms by measuring growth rates in batch culture. To maintain a constant inoculum for the experiments inoculum was taken from a continuously operating continuous culture. Two populations were studied corresponding to two separate residence times in the continuous culture apparatus. One contained predominantly filamentous organisms, the other nonfilamentous. Five kinetic models were applied to the data and the best kinetic parameters for each model were determined by nonlinear least squares techniques. The models were then evaluated for best relative fit to the data. No significant differences were found between the models on the basis of fit and so a choice was made on the grounds of simplicity. A model proposed by Haldane was chosen as the best. No function however gave a satisfactory fit at the highest growth rates obtained. This experimental maximum in the plot of growth rate against substrate concentration was very sharp.
Thermal stability of glucose oxidase and its admixtures with synthetic polymers
Authors: O'malley James J. , Ulmer Robert W. 
Published: December 2004

AbstractThe thermal stability of glucose oxidase in solution was studied as a function of time and temperature between 37–60°C. As expected, the rate of thermal inactivation increased with temperature and at 60°C more than 80% of the enzyme's activity was lost after 0.5 hr incubation. Similar stability measurements on enzyme solutions containing water soluble synthetic polymers showed that several of the polymers significantly enhanced the thermal stability of glucose oxidase. Copolymers of vinyl acetate with either vinyl pyrrolidone or vinyl alcohol were found to be particularly effective. The molecular weight of the added polymers was found to be unimportant in the stabilization process but both polymer concentration and compositions were shown to be critical parameters.
Growth yields of microorganisms on methanol and methane. A theoretical study
Authors: Van Dijken J. P. , Harder W. 
Published: December 2004

AbstractAn attempt was made to calculate growth yields of microorganisms on methanol and methane on the basis of known biochemical pathways of C1 metabolism. Since 3‐phosphoglycerate is a key intermediate in the assimilation pathways of C1 compounds, the calculations were based on the assumption that the synthesis of cell material from C1 substrates can be regarded as a two step process. When YATP on 3‐phosphoglycerate was taken as 10.5, a maximal cell yield of organisms of the composition C4H8O2N on methanol was found to be 0.73 g cells/g substrate. For growth on methane a value of 0.91 g cells/g substrate was calculated when a mixed function oxidase was implicated in methane oxidation. These yields were calculated on the basis of the ribulose phosphate pathway of formaldehyde fixation as the major pathway of C1 assimilation. Yields calculated on the basis of the serine pathway were on an average 20% lower. The calculations disclosed that for growth on methane, at least for Methylococcus capsulatus, a reversed electron transport system is required when methane is oxidized by a mixed function oxidase. The theoretical cell yields on methanol and methane have been compared with experimentally obtained yields and the validity of the estimations of growth yields on the basis of the present calculations is discussed.
Enzymatic breakdown of water insoluble substrates
Authors: Suga K. , Van Dedem G. , Moo‐Young M. 
Published: December 2004

AbstractThe kinetic behavior of the enzymatic breakdown of crosslinked dextran (Sephadex) by a dextranase from Penicillium funiculosum was investigated as a model for enzymatic degradation of insoluble materials. A theoretical model is developed for the description of an enzymatic reaction on an insoluble substrate. Experimental data are compared to those predicted by the model which are calculated by using independently determined parameter‐values such as the Michael is constants, effective pore radius of the particles, and the Stokes radius of the enzymes. Fairly good agreement was found between the theoretical analysis and the experimental data.
Fermentation of waste mechanical fibers from a newsprint mill by the rot fungus Sporotrichum pulverulentum
Authors: Eriksson Karl‐Erik , Larsson Kjell 
Published: December 2004

AbstractThe growth and protein production of Sporotrichum pulverulentum, formerly called Chrysosporium lignorum, have been studied in submerged cultures using lignin‐containing waste fibers from a newsprint mill as the only carbon source. The influence of different nitrogen sources on the growth parameters has been particularly investigated. The regulation of the production of extracellular enzymes and their interaction with the fibers is discussed. Experiments with cellulose of different degrees of polymerization and crystallinities showed that the protein content in the residual substance decreased, particularly when the crystallinity increased. When the highly crystalline powder cellulose was used as carbon source, the protein content in the residual substance was only 6% and with the mechanical waste fibers 14%. The results obtained demonstrate that the more complex the carbon source the more difficult it is to digest and the more enzyme has to be produced for its degradation. This puts a heavy burden on the protein synthesizing mechanism. Utilizing results from other work, where the endo‐ and exo‐l, 4‐β‐glucanases produced by S. pulverulentum for the degradation of cellulose have been quantitatively purified, it has been calculated that the extracellular enzymes under these conditions can together account for approximately 30% of the protein in the mycelium. The endo‐ and exo‐1,4‐β‐glucanases account for up to 55% of the extracellular protein.Certain possibilities of producing a final product with a high protein content using complex carbon sources are also mentioned.
Efficient biokinetic experimental designs
Authors: Johnson David B. , Berthouex Paul M. 
Published: December 2004

AbstractOf the experimental methods available for obtaining data to estimate the biological kinetic parameters μm,Ks, andYeach requires considerable experimental effort, yet often yields somewhat imprecise estimates of the parameters, particularlyKs. Therefore it would be worthwhile to seek ways to get parameter estimates of greater precision using less experimental effort. The precision of parameter estimates is strongly dependent, upon the settings of the independent, variables used in the experiments. This dependence is explained and an attempt made to show how experimental settings can be determined that lead efficiently to precise parameter estimates with minimal effort.
A model for diauxic growth
Authors: Van Dedem G. , Moo‐Young M. 
Published: December 2004

AbstractA model is developed to predict batch and continuous culture behavior of fermentations on two different carbon and energy sources. The basic assumption of the model is that the permease for the favored substrate is constitutive, whereas the permease for the second substrate is subject to induction and catabolite repression. Simulations of the model show features of diauxic growth described in the literature.
Kinetic studies of mold α‐galactosidase on PNPG hydrolysis
Authors: Kobayashi Harumi , Suzuki Hideo 
Published: December 2004

AbstractThe kinetic properties of α‐galactosidase of Mortierella vinacea were investigated in detail using PNPG (p‐nitrophenyl‐α‐D‐galactopyranoside) as a substrate. Consequently, the enzyme was markedly inhibited not only by the substrate, but also by the galactose hydrolized. The initial rate of reaction at sufficiently high substrate concentrations, however, did not fall to zero and did approach a finite value. Galactose behaved as a mixed inhibitor and was neither totally competitive nor totally noncompetitive. A rate equation was obtained from a generalized equation derived from a kinetic model which took both the inhibitions into consideration. The constants used in the equation were appropriately estimated. The calculated rate agreed fairly well with the observed initial rate. Moreover, the PNPG hydrolysis progressing in a batch system was found to be approximately representable by simple first order kinetics in which the rate constant was dependent on the initial substrate concentration.
New mechanisms for the biosynthesis and metabolism of 2‐keto‐L‐gulonic acid in bacteria
Authors: Makover S. , Ramsey G. B. , Vane F. M. , Witt C. G. , Wright R. B. 
Published: December 2004

AbstractL‐Sorbose is oxidized to 2‐keto‐L‐gulonic acid (KGA) via the following sequence of reactions which we call the “sorbosone pathway”: L‐sorbose ⇌ L‐sorbosone → KGA. The first step is reversible and is mediated by enzymes found in a soluble fraction obtained from Pseudomonas putida ATCC 21812. Although no cofactor requirements were found for the forward reaction, the reverse reaction clearly required NADH. Enzymes for this NADH‐dependent synthesis of L‐sorbose could be differentiated on the basis of molecular weights. The second step in the sorbosone pathway is catalyzed by a particulate enzyme found in extracts from P. putida and Gluconobacter melanogenus IFO 3293. The rate limiting reaction in the sorbosone pathway is the synthesis of L‐sorbosone. In addition to P. putida, Klebsiella pneumoniae (ATCC 27858) and Serratia marcescens (ATCC 27857) also contain the enzymes which catalyze the reactions of the sorbosone pathway. Two of the bacteria studied, P. putida and G. melanogenus, also contain an enzyme involved in the further metabolism of KGA to L‐idonic acid. This enzyme, referred to as KGA‐reductase, is found in the soluble fraction of cell‐free extracts and is dependent on NADH or NADPH.
Preparation of immobilized β‐galactosidase by poly(vinylpyrrolidone) and the continuous hydrolysis of lactose in acid whey
Authors: Maeda Hidekatsu 
Published: December 2004

AbstractImmobilized β‐galactosidase gel was prepared using poly(vinylpyrrolidone) (PVP) under β‐ray irradiation. In contrast to the gelation of N‐vinylpyrrolidone monomer–enzyme solution, the gelation of PVP‐β‐galactosidase solution (PVP content: 10%) was almost completely uneffected by the dose rate and amount of phosphate present. PVP‐enzyme solution was gelled by irradiation with 3.0 Mrad. The expressed activity of the PVP‐enzyme gel was about 30% of the initial activity and added activity was almost totally entrapped. No leakage of enzyme from these gels could be detected. Leakage was, however, detected in the case of the gelation of PVP‐enzyme solution containing more than 1% of enzyme protein. When the general properties of the gel were compared with those of the native enzyme, the gel proved to be slightly inferior to the native enzyme with respect to optimum temperature, heat stability, pH activity, and pH stability. Continuous hydrolysis of lactose in acid whey could be carried out at 50°C using a column packed with the gel and sawdust and the degree of hydrolysis was found to be almost, constant for 12 days. The merits of using PVP in the immobilization of enzymes include the simplicity of the procedure and the fact that the PVP‐enzyme gel can be used in the food industry without anxiety because of its high degree of compatibility with living organisms.
Substrate inhibition kinetics: Phenol degradation by Pseudomonas putida
Authors: Hill Gordon A. , Robinson Campbell W. 
Published: December 2004

AbstractA pure culture of Pseudoinonas putida was grown in both a batch and continuous culture using phenol as the limiting substrate. Of two substrate inhibition models examined, the Haldane function was found to statistically best describe the kinetics. The applicable kinetic constants were either measured (μM, KI) or estimated (KS) from the experimental data. Particularly in the continuous culture, wall growth was found to exert significant effects on the broth biomass concentration and phenol conversion, both of which decreased with increasing amounts of wall growth. These effects are opposite to those predicted by wall growth models and to experimental results of others using mixed culture (activated sludge) systems.
The preparation and properties of hornblende as a support for immobilized invertase
Authors: Thornton D. , Flynn A. , Johnson D. B. , Ryan P. D. 
Published: December 2004

AbstractThe suitability of hornblende as a support for immobilized β‐fructofuranosidase (invertase) was studied, with regard to the physical stability of the support and the thermal and operational stability of the immobilized enzyme. Hornblende was more stable than Enzacryl‐Alo or Enzacryl‐TIO, and marginally more stable than porous glass. Invertase immobilized on hornblende was more stable during long‐term operation than invertase immobilized on porous glass. An active preparation of immobilized invertase was obtained also on pyroxene particles.
Variable‐volume continuous cultivation
Authors: Dunn I. J. , Mor J.‐R 
Published: December 2004

AbstractEquations are developed which describe variable‐volume cultivations, including fed‐batch systems. An analogy is drawn between the quasi‐steady state in variable‐volume cultivation and a dynamic steady state in variable‐flow, constant‐volume chemostat bioreactors. Switching procedures are developed to give a steady‐state transition from batch to fed‐batch and to continuous operation. In this respect, considerations in the literature have been extended. Computer solutions of the governing differential equations verify the theory and provide insight into the behavior of variable‐volume stirred tank reactors.Application of variable‐volume cultivation as a tool in investigating growth rates at low substrate levels is suggested. Variable‐volume bioreactor systems could be also to obtain controlled dynamic conditions for research or production purposes.
Macrokinetics and operational stability of immobilized glucose oxidase and catalase
Authors: Buchholz K. , Gödelmann B. 
Published: December 2004

AbstractGlucose oxidation by immobilized glucose oxidase (GlO) and catalase (Cat) has been investigated in batch and continuous reactions for operational studies. The macrokinetics of the process depend on coupled reaction steps and diffusion rates. The problem may be approximated by a simple pseudohomogeneous model taking into account both substrates of glucose oxidase and the intermediate reaction product H2O2. The effectiveness of both enzymes is enhanced in the coupled reaction path, the overall effectiveness nevertheless is very low. H2O2 causes the inactivation of both GlO and Cat. The rates of deactivation depend on the oxidation rates of glucose that give different quasistationary levels of H2O2 concentration. As a first approximation, the deactivation rates may be described by first‐order reactions with respect to H2O2.
Application of mass and energy balance regularities to product formation
Authors: Erickson L. E. , Selga S. E. , Viesturs U. E. 
Published: December 2004

AbstractMaterial and energy balances for fermentation processes with product formation are developed using regularities which are frequently useful in analyzing experimental results. Available electron balances are presented and used to analyze the results of experiments in which biomass and lysine are produced in batch culture using molasses and corn extract as organic substrates. Measured values of biomass productivity, lysine productivity, O2 consumption rate, heat evolution rate, CO2 evolution rate, and rate of utilization of reducing sugars (RS) are used to obtain estimates of biomass energetic yield, lysine energetic yield, and fraction of substrate energy evolved as heat. For two of the three experiments, based on the entire fermentation, the measured mass rate variables are very consistent and energy measurement errors are less than 10% when proper consideration is given to both the RS and the amino acids present in the organic substrate. The average measured value of 26.5 kcal/equivalent (equiv) of available electrons transferred to oxygen compares favorably with the known average value of 27 kcal/equiv.
Immobilization of enzymes on activated carbon: Properties of immobilized glucoamylase, glucose oxidase, and gluconolactonase
Authors: Cho Y. K. , Bailey J. E. 
Published: December 2004

AbstractApparent kinetics and pH–activity relationships have been determined for glucoamylase and glucose oxidase immobilized on activated carbon using a diimide method. Reaction rate expressions of Michaelis–Menten form adequately approximate the observed kinetics for both enzyme preparations over the ranges of substrate concentrations considered. Influences of external mass transfer as well as substrate and product adsorption on interpretation of the experimental data have been examined. Immobilization of a glucose oxidase–gluconolactonase enzyme mixture has been found to increase substantially the ratio of gluconolactonase to glucose oxidase activities compared to the corresponding activity ratio for these enzymes in solution.
Photocontrol of affinity chromatography: Purification of asparaginase by photosensitive AHA‐gel
Authors: Karube Isao , Ishimori Yoshio , Suzuki Shuichi , Sato Toshio 
Published: December 2004

AbstractAn agarose gel modified with N‐(ω‐aminohexytl)‐L‐aspartic acid (AHA) and spiropyran compound (AHA–spiropyran gel) was prepared and the photocontrolled binding and releasing of asparaginase were investigated with the AHA–spiropyran gel. Asparaginase was bound on the AHA–spiropyran gel under visible light and was released in the dark. The optimum conditions for photocontrolled binding and releasing of asparaginase were a 0.05M phosphate buffer concentration and pH 7.0. Seventy‐five percent of the bound asparaginase was released from the AHA–spiropyran gel column in the dark. Ninetyfold purification of asparaginase was performed with the AHA–spiropyran gel Column.
Parameter evaluation and performance studies in a fluidized‐bed immobilized enzyme reactor
Authors: Emery A. N. , Cardoso J. P. 
Published: December 2004

AbstractDispersion and mass‐transfer characteristics and fluidization parameters influencing the performance of a small pilot‐plant immobilized enzyme reactor are evaluated. The suitability of a dispersed plug‐flow model to predict the conversions obtained in the enzymatic reaction (starch → glucose) catalyzed by amyloglucosidase immobilized to solid and porous carriers is assessed. The performance of a fluidized‐bed reactor is compared on the basis of a normalized residence time with that of a fixed bed and found to be superior.
Effect of diffusion limitations and floc size distributions on fermentor performance and the interpretation of experimental data
Authors: Atkinson B. , Rahman F.‐Ur‐ 
Published: December 2004

AbstractThe biological rate equation that describes the overall rate of substrate uptake by microbial films has been extended to microbial flocs with the aid of a shape parameter. The “solid”‐ and liquid‐phase diffusion limitations are explored and found to depend largely on a dimensionles characteristic size k21Vp/Ap. Procedures are discussed by which k21Vp/Ap can be determined from experimental data on the conversion efficiency in a completely mixed fermentor and measurements carried out on flocs recovered from the fermentor are assessed. Floc size distributions are shown to affect the performance characteristics of a fermentor when some of the flocs are sufficiently large to exhibit a diffusional limitation, and it is concluded that a single mean floc size (k21Vp/Ap)* is sufficient to characterize a given distribution, at least when all the flocs are geometrically similar. The mean floc size closely corresponds to the “surface” mean floc size of the floc size distributions.
Pulp and paper mill solid wastes as substrates for single‐cell protein production
Authors: Pamment N. , Robinson C. W. , Moo‐Young M. 
Published: December 2004

AbstractWe have investigated the upgrading of some typical pulp and paper mill solid wastes into protein‐enriched animal feed using the cellulolytic fungus Chaetomium cellulolyticum. The waste residues used were six different primary clarifier sludges and a sample of tertiary centricleaner rejects. These were obtained from mills whose modes of operation spanned the range typically in present‐day usage: groundwood, sulfite, semichemical, Kraft, and thermomechanical pulping, with and without bleaching. Crude protein production from the solid waste residues is compared to that obtainable from fermentation of untreated or caustic‐pretreated sawdusts. Some of these waste residues, especially the Kraft pulp mill rejects, appear to be promising sources of substrate for single‐cell protein production. In these preliminary findings, up to 28% dry weight crude protein content of the product has been obtained at specific growth rates of up to 0.12hr−1 on direct utilization of the wastes.
Bioprobe electrode for phenol
Authors: Neujahr Halina Y. , Kjellén Karin G. 
Published: December 2004

AbstractA clark oxygen electrode is coated with a thin layer of cell paste of induced trichosporon cutaneum. This bioprode enables one to perform rapid, quantitative determination of phenol in the 0–15 mg/liter range. The assay uses only 2–5 ml and is complete 15 sec after adding the sample. The bioprobe is stable for at least five days at room temperature. It lasts at least 100 assays. Induced yeast cells come from shake cultures or agar plates. They can be freeze‐stored for several weeks before mounting on the electrode. A method of estimating corrections for other exidizable substances is exemplified. The bioprobe can be used to measure phenol in water, fermentation broth, and municipal sewage.