bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immobilized tannase
Authors: Weetall H. H. , Detar C. C. 
Published: December 2004

AbstractThe enzyme tannase has been immobilized on an inorganic support by covalent attachment. This immobilized enzyme was characterized and half‐lives determined. Since this enzyme has application in the treatment of tea cream, experiments were also carried out to determine the effect of tea on enzyme half‐life.
Enzymatic RNA reduction in disintegrated cells of Saccharomyces cerevisiae
Authors: Lindblom Marianne , Mogren Håkan 
Published: December 2004

AbstractDegradation of UNA by endogenous RNase in cell suspensions of Saccharomyces cerevisiae was found to be achieved by mechanical disintegration followed by incubation in the presence of NaCl. The incubation parameters pH, temperature, time, and concentration of NaCl were investigated. Protein concentrates with a low content of RNA were obtained by precipitation of the incubated suspensions and separation of the degradation products.On a pilot plant scale the incubation was performed at 50°C and pH 5.6 in the presence of 3% NaCl for 20 min. Kilogram quantities of protein concentrates containing 1.4% RNA and 8.2% nitrogen were obtained. The RNA reduction and the nitrogen yield was 85 and 60%, respectively. The yield of amino acids was about 75%. The process described can probably be applied for large‐scale production.
Stability of commensalistic systems
Authors: Reilly Peter J. 
Published: December 2004

AbstractThe response of two‐species commensalistic systems in a chemostat has been investigated after perturbations in steady state conditions and after step changes in dilution rate. The system is inherently stable with not more than three overshoots and undershoots possible. More complicated commensalistic systems are less stable, with limit cycle response occurring after dilution rate changes when feedback inhibition and feedforward activation occurs. In general variation of feedback parameters is more effective in changing the behavior of the systems than variation of feedforward parameters. Limited agreement with the experimental data of Chao and Reilly was obtained.
Optimization in the recovery of a labile intracellular enzyme
Authors: Augenstein D. C. , Thrasher K. , Sinskey A. J. , Wang D. I. C. 
Published: December 2004

AbstractA high molecular weight intracellular enzyme of Bacillus brevis ATCC 9999 is released when the organism is disrupted by sonication of homogenization. However, both processes also degrade the enzyme. Assays for protein release and specific enzymatic activity of the released protein indicate that both release and degradation can be represented by first‐order kinetic models. Utilization of the difference between the kinetics of release and degradation allows optimization in the recovery of this enzyme for both the sonication and homogenization processes.
Preparation of immobilized enzymes by N‐Vinylpyrrolidone and the general properties of the glucoamylase gel
Authors: Maeda H. , Suzuki H. , Yamauchi A. , Sakimae A. 
Published: December 2004

AbstractImmobilized glucoamylase, invertase, and β‐galactosidase were prepared by using N‐vinylpyrrolidone monomer (VP) under γ‐ray irradiation. The enzyme‐VP solutions were gelled by irradiation with 2.9 Mrad and the added enzymes were almost completely entrapped. Activity losses on entrapping were 55% for the VP‐glucoamylase gel, and more than 90% in the case of VP‐invertase and VP‐β‐galactosidase gels. No leakage of enzyme from these gels could be detected within 1 hr. The VP‐glucoamylase gel was capable of hydrolyzing dextrin (mol wt 10,400) to glucose and the glucose equivalent was equal to that obtain able with native enzyme. The optimum temperature, heat stability, pH activity curve, and pH stability of VP‐glucoamylase gel were slightly inferior to those of native enzyme, while Km was a little larger than that of native enzyme.
Continuous production of L‐citrulline by immobilized Pseudomonas putida cells
Authors: Yamamoto Kozo , Sato Tadashi , Tosa Tetsuya , Chibata Ichiro 
Published: December 2004

AbstractThe microbial cells of Pseudomonas putida ATCC 4359 were immobilized by entrapment in a polyacrylamide gel lattice. Enzymatic properties of L‐arginine deiminase of the immobilized P. putida cells were investigated and compared with those of the intact cells. The permeability of substrate or product through the cell wall und the heat stability of the enzyme were increased by immobilization of the cells. No difference was observed between pH activity curves of the intact and immobilized cells. The optimal temperature for the formation of L‐citrulline was 37°C for the intact cells and 55° C for the immobilized cells.When an aqueous solution of 0.5M L‐arginine hydrochloride (pH 6.0) was passed through a column packed with the immobilized cells at a flow rate of SV = 0.26 at 37°C, L‐arginine was completely converted to L‐citrulline. The enzyme activity of the column was stable and the continuous production of L‐citrulline could be carried out at 37°C for the month by using the immobilized cell column. From the effluent of the column, L‐citrulline was easily obtained in a good yield.
Continuous production of urocanic acid by immobilized Achromobacter liquidum cells
Authors: Yamamoto Kozo , Sato Tadashi , Tosa Tetsuya , Chibata Ichiro 
Published: December 2004

AbstractSeveral microorganisms having higher L‐histidine ammonia‐lyase activity were immobilized into polyacrylamide gel lattice. The yield of enzyme activity by immobilization was highest in Achromobacter liquidum IAM 1667. As A. liquidum has urocanase activity, the cells were heat‐treated at 70°C for 30 min to inactivate the urocanase.Enzymatic properties of the immobilized A. liquidum cells were investigated and compared with those of the intact cells. No difference was observed between the pH activity curve and optimal temperature for the intact and immobilized cells. The permeability of substrate or product through the cell wall was increased by immobilization of the cells.When an aqueous solution of 0.25M L‐histidine (pH 9.0) containing 1mM Mg2+ was passed through a column packed with the immobilized A. liquidum cells at a flow rate of SV = 0.06 at 37°C, L‐histidine was completely converted to urocanic acid. The L‐histidine ammonia‐lyase activity of the immobilized cell column was stable over 40 days at 37°C. From the effluent of the immobilized cell column, Urocanic acid was easily obtained in a good yield.
Performance characteristics of continuous yeast‐alcohol fermentors with no mechanical stirring
Authors: Wick Emil , Popper Karel , Graham Robert P. 
Published: December 2004

AbstractContinuous fermentation of grape juice was studied in three basic kinds of nonmechanically stirred fermentors, classified according to the direction in which flow is applied against settling: upward‐flow, slant‐flow, and horizontal‐flow.Fermentation kinetics were found to be zero‐order, thus rate was directly proportional to cell density.Completeness of fermentation depends upon yeast characteristics (growth rate flocculation), fermentor geometry (settling depth, flow path length), and upon flow velocity.Fermentor analysis demonstrated that to achieve complete fermentation in the minimum juice holding time, efficient cell retention as well as rapid yeast growth and fermentation rates are required. Fermentor design and operation are discussed in the light of this analysis.
Automated instrument for measuring biological transport kinetics over intervals of a few seconds
Authors: Brown Olen R. , Barton Jerry 
Published: December 2004

AbstractAutomated sampling device was designed to permit determination of rates of biological transport of metabolites into cells. The substrate was automatically introduced into a stirred cell suspension at 37°C. The first sample was automatically taken after a mixing interval of 1 sec and nine subsequent samples were taken at programmable intervals (1 to 100 sec). The samples were forced by pressure differential (vacuum) through 0.4 μ pore size membranes and approximately 50 μl were collected in disposable cups. The duration of the sampling interval was controllable down to 0.1 sec. The samples preserved records of the substrate concentrations in solution at the time of filtration. With the use of suitable radioactive labeled isotopes, the changes in substrate concentrations may be conveniently measured by liquid scintillation spectrometry, but other analytical procedures of suitable sensitivity may be used. Initial and steady‐state transport rates of succinate and glucose in Escherichia coli were obtained using the device.
Deactivation of immobilized beef liver catalase by hydrogen peroxide
Authors: Altomare Robert E. , Kohler Joseph , Greenfield Paul F. , Kittrell James R. 
Published: December 2004

AbstractImmobilized beef liver catalase has been used in a flow reactor to decompose hydrogen peroxide; at the same time the catalase is inactivated by its substrate. A model has been developed which predicts this rate of decomposition of peroxide and inactivation of catalase. First order dependence on peroxide concentration is assumed. The model was verified by experiment for a range of operating conditions and then used to predict the effects of a change in operating variables.
Response of biological reactors to sinusoidal variations of substrate concentration
Authors: Sundstrom D. W. , Klei H. E. , Brookman G. T. 
Published: December 2004

AbstractA well‐mixed biological reactor with continuous addition of biological solids was subjected to sinusoidal variations in inlet substrate concentration. The phase lag between inlet and outlet concentrations increased with increasing frequency. The deviation of measured substrate concentrations from initial steady‐state concentrations was observed to have a maximum near a frequency of 1 cycle per residence time. Measured concentrations of substrate and biomass in the reactor differed significantly from concentrations predicted by the Monod kinetic model.
Influence of oxygen and substrate concentrations on the ideal film thickness and the maximum overall substrate uptake rate in microbial film fermenters
Authors: Howell J. A. , Atkinson B. 
Published: December 2004

AbstractThe criterion for the oxygen limitation of substrate uptake in microbial film fermenters is expressed in terms of diffusion coefficients, utilization coefficients, and the free solution concentrations of substrate and oxygen. It is proposed that the ideal film thickness in such fermenters is equal to the penetration depth of the limiting substrate. The ideal film thickness is calculated, in terms of the parameters contained in the criterion for oxygen limitation, for three separate kinetic rate expressions. It is found that for the air–glucose–microbe system a simplified kinetic rate expression can be used and the region of dependence on two substrates is shown to be very limited. This is not true for other systems. Maximum uptake rates are calculated for a range of concentrations. Finally, it is shown that the procedure used can be generalized to determine the limiting substrate in a multisubstrate system and to calculate ideal film thickness and uptake rates for any pair of substrates where the kinetics of substrate uptake are known for the individual microorganism.
Kinetic studies of α‐galactosidase‐containing mold pellets on PNPG hydrolysis
Authors: Kobayashi Harumi , Suzuki Hideo 
Published: December 2004

AbstractLittle is known about techniques for applying untreated microbial cells containing enzymes directly to industrial processes as a biocatalyst. The kinetic behavior of α‐galactosidase‐containing spherical pellets which are formed naturally under given conditions in a submerged culture of Mortierella vinacea was studied on the hydrolysis of PNPG (p‐nitrophenyl–α–D‐galactopyranoside). The effect of intraparticle diffusion on the overall reaction rate was assessed by the use of an effectiveness factor, which was calculated by the approximate solution to the equation derived from the mass balance within a pellet. The experimental effectiveness factors were found to be represented as a single function of the modified Thiele modulus, including such parameters as pellet size, enzyme concentration in the pellet, and substrate concentration. As the diffusional effect became more significant, the marked substrate inhibition as seen for a five enzyme disappeared gradually. The effect of product inhibition on the pellets was much weaker than that for a free enzyme at a given substrate concentration. In the region of diffusion controlled reaction, it was found that the rate is proportional to the square root of the enzyme concentration in the pellet. In addition, similarly to what was reported previously for a free enzyme, the reaction in a batch system was found to be approximately representable as simple first‐order kinetics in which the rate constant was dependent on the initial substrate concentration.
Combined external and internal mass transfer effects in heterogeneous (enzyme) catalysis
Authors: Frouws M. J. , Vellenga K. , De Wilt H. G. J. 
Published: December 2004

AbstractA graphical method is outlined in order to calculate the conversion under combined intra‐ and extraparticle transport limitations using the existing effectiveness factor charts for intraparticle diffusion.This method is applied to the case of an immobilized enzyme, assuming that the kinetics are of the Michaelis‐Menten type.
Temperature dependence of a diffusion‐limited immobilized enzyme reaction
Authors: Buchholz K. , Rüth W. 
Published: December 2004

AbstractThe apparent activation energy of N‐α‐benzoyl‐L‐arginine‐ethyl ester (BAEE) hydrolysis by immobilized trypsin varies with the bulk substrate concentration from its maximum value, comparable to that of the free enzyme, to considerably lower values. Thus, with a concentration change from 3 × 10−2 to 10−4 M the apparent activation energy diminishes from 9.5 to 4.5 kcal/mol. This experimental finding is interpreted to be due to Michaelis‐type kinetics in a heterogeneous system, in one case reflecting the temperature dependence of the maximal enzyme reaction rate, in another case illustrating the diffusion limited overall reaction at low substrate concentrations. As a consequence it may not be feasible to operate a reaction at elevated temperatures in a high conversion range, since diffusion limitation may restrict the enhancement of the overall reaction rate. Some further data are given concerning the buffer effect on the reaction rate, which should occur due to its limitation by proton transfer in the buffer‐free system.
Conversion of L‐sorbose to L‐sorbosone by immobilized cells of Gluconobacter melanogenus IFO 3293
Authors: Martin C. K. A. , Perlman D. 
Published: December 2004

AbstractGluconobacter melanogenus IFO 3293 cells capable of converting L‐sorbose to L‐sorbosone were immobilized in polyacrylamide gel. The preferred polymer composition for high activity and stability was determined to contain a total monomer concentration of 7.2% and 16.6% crosslinking agent. No significant differences in optimal conditions for conversion, e. g., pH and temperature, were found in comparison with free cell suspensions. However, in the absence of L‐sorbose, the thermal stability of immobilized cells was lower. After the initial loss, the conversion activity of immobilized cells increased, possibly due to lysis, and this increase was related to the polymerization conditions and the incubation temperature for the L‐sorbose conversion.The enzymatic activity and stability of the immobilized cells also depended on the physical form of the gel and the aeration levels. Addition of electron acceptors or addition of L‐sorbosone to the medium reduced, while addition of neomycin, ampicillin, chloramphenicol, and tetracycline increased the stability of the enzymatic activity.
Protozoan feeding and bacterial wall growth
Authors: Bonomi Antonio , Fredrickson A. G. 
Published: December 2004

AbstractMonod's model is often assumed to describe the kinetics of feeding of a protozoan population on a bacterial population in a chemostat. An earlier study (J. L. Jost et al., J. Bacteriol, 113, 84 (1973)) of the feeding of Tetrahymena pyriformis on either Escherichia coli or Azotobacter vinelandii found that this model correctly predicted the occurrence of sustained oscillations of population densities but made predictions of minimum bacterial population densities that were much smaller than those observed. The earlier study removed the discrepancy between the model and data by replacing Monod's model with a different model. It is shown in the present study that the discrepancy can be explained equally as well if Monod's model for the feeding relation is retained and if, in addition, growth of bacteria on the chemostat walls is allowed for in the model equations.
Pilot plant production of glucose with glucoamylase immobilized to porous silica
Authors: Lee Douglas D. , Lee Yoon Y. , Reilly Peter J. , Collins Edgar V. , Tsao George T. 
Published: December 2004

AbstractGlucoamylase was immobilized to porous silica and its kinetics and stability were observed with acid‐ and α‐amylase‐hydrolyzed dextrin as feed. The enzyme was found to be extremely stable in both laboratory and pilot plant operations. When the feed had been previously only lightly hydrolyzed, pore diffusion limitation caused appreciable decreases in glucose production rate. The severity of starch hydrolysis to dextrin markedly affected ultimate glucose yields. The diffusional gradients present in the carrier pores caused the immobilized enzyme to yield lower glucose concentrations than the free enzyme at similar feed conditions.
Daughter cells as an important factor in determining the physiological state of yeast populations
Authors: Vraná Dagmar 
Published: December 2004

AbstractCells of Candida utilis grown in a single‐stage chemostat at D = 0.05, 0.1, 0.25, and 0.35 hr−l were separated into a fraction of scar‐bearing mother cells and a fraction of scar‐free daughter cells. The scar‐free cells were transferred into small batch cultures where the length of the maturation phase, changes in length and width of cells, specific growth rate, and specific rate of RNA and protein synthesis were examined for 5 hr. The daughter cells grown at D = 0.05 hr−1 were very small at the moment of separation from the mother cells (about one‐third of the mother cell). Their maturation phase (in a batch culture), at the beginning of which they attain the specific growth rate approaching the μmax of the strain used, lasts for 3 hr. On the other hand, daughter cells grown at D = 0.35 hr−1 are almost the same size as the mother cells at the moment of separation. After transfer to a batch culture they begin to bud almost immediately. Similarly, in their other morphological and physiological parameters they differ strikingly from immature daughter cells which are formed at low specific growth rates. The importance of these differences from the point of view of mathematical modeling of growth processes is discussed.
A heat transfer study on packed bed reactors of immobilized glucoamylase
Authors: Marsh David R. , Tsao George T. 
Published: December 2004

AbstractEnzymes are generally sensitive to temperature changes. Porous glass particles used for glucoamylase immobilization are poor thermal conductors and a non‐uniform temperature distribution can conceivably develop in a packed bed reactor of immobilized glucoamylase on porous beads. This study was made to determine experimentally the temperature and concentration profiles in an immobilized glucoamylase column. This work provides a procedure for examining possible heat effects on reactor column performance in enzyme applications.
Inhibition‐threshold substrate concentrations
Authors: Wayman M. , Tseng M. C. 
Published: December 2004

AbstractA proposed substrate inhibition model (M. C. Tseng and M. Wayman, Can. J. Microbiol., 21, 994 (1975)),

derived from yeast growth rates has been applied to data for bacterial growth: Pseudomonas methanica grown on methanol and Arthrobacter AK19 grown on n‐butanol. The model represents the experimental data very well.
The effect of aeration intensity on the biochemical composition of Baker's yeast: Activities of enzymes of the glycolytic and pentose phosphate pathways
Authors: Oura Erkki 
Published: December 2004

AbstractA series of baker's yeast continuous cultivations were made using different intensities of aeration. The experimental conditions were such as to eliminate the effects caused by high glucose concentrations in the medium on the formation of enzymes. The variation in activity of several enzymes was investigated and distinct changes were noted. The activities of hexokinase and alcohol dehydrogenase characterize the actual rate of glycolysis in yeast, the same being true, in part, for pyruvate decarboxylase. The activity of phosphofructokinase is nearly insensitive to the oxygen level at normal tensions. The activity of the cell to the phosphofructokinase can be limited in anaerobic conditions by its scarcity. The insensitivity of glucose‐6‐phosphate dehydrogenase to the oxygen tension together with its low activity suggests that this enzyme plays primarily a biosynthetic role and that the function of the pentose phosphate pathway as an energy‐producing route is negligible.
The kinetics of protein salting‐Out: Precipitation of yeast enzymes by ammonium sulfate
Authors: Foster P. R. , Dunnill P. , Lilly M. D. 
Published: December 2004

AbstractProtein solubility can be adequately represented by the classical Cohn equation for the salting‐out of alcohol dehydrogenase and fumarase from clarified yeast homogenate with ammonium sulfate. However, the constant β in this equation is a function of the contacting procedure employed. The kinetics of continuous salting‐out were similar for alcohol dehydrogenase and fumarase. The overall rate equation for precipitation had a variable order which was high initially, up to 3.1, but approached unity on completion of precipitation. This was followed by a partial resolution stage which was first order with respect to the concentration driving force. Precipitate particle size was estimated as 0.5 to 5 μm with continuous flow precipitation producing the largest particles.
Growth kinetics of a yeast grown on glucose or hexadecane
Authors: Mason T. J. , Millis N. F. 
Published: December 2004

AbstractThe kinetics of growth of a Torulopsis sp. was investigated in a continuous culture with glucose or hexadecane as the carbon source; growth was limited by either carbon or nitrogen. The relationship between the concentration of the limited substrate and the steady‐state growth rate of the organism was examined and tested against various models of growth. No existing model was found to describe the growth accurately and a new model has been proposed:

It is postulated that this behavior would result from a simple first order reaction between the reactants of the rate‐limiting enzymic reaction of the organism's metabolism.
External mass transfer in a biological film reactor
Authors: La Motta Enrique J. 
Published: December 2004

AbstractA method for calculating the mass transfer coefficient in a biological film system, under turbulent flow conditions, is presented. It is experimentally found that fluid velocity has a positive effect on the rate of substrate utilization when the system is operated in other than the kinetic regime. A correlation is developed which indicates a dependence of the mass transfer coefficient on the fluid velocity raised to the 0.7 power.