bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steroid transformation at high substrate concentrations using immobilized Corynebacterium simplex cells
Authors: Constantinides Alkis 
Published: December 2004

AbstractThe steroid transformation of hydrocortisone to prednisolone, combining the two techniques of immobilized whole cells and high steroid concentrations, was investigated and found to be a feasible process. Freeze‐dried Corynebacterium simplex cells were immobilized in collagen, tanned with glutaraldehyde, and cast into a membrane. The reaction was studied at hydrocortisone concentrations ranging from 5 to 50 mg/ml. The following aspects of the system were examined: (1) the substrate concentration effect upon the reaction; (2) the effect of enzyme concentration; (3) the rate‐concentration relationship; and (4) the product inhibition characteristics of the system. The optimal substrate concentration was found to be 15 mg/ml of a membrane concentration of 80 mg/ml. This reaction attained an 80% conversion in 48 hr. A liner relation was found between the initial reaction rate and membrane concentration. One can thus increase the net production of steroid per unit volume and time by increasing the membrane levels. A physical limit to this increase occurred at membrane concentrations greater than 125 mg/ml. The rate‐concentration relationship was linear when graphed on a Line weaver‐Burk plot: giving a Km′ and Vm′ value of 5.39 mg/ml and 0.556 mg/ml/hr, respectively. When the data were tested for competitive product inhibition, the curves fitted the experimental points fairly well and produced Km′ and Vm′ values of 4.52 mg/ml and 0.566 mg/ml/hr, respectively. Product inhibition experiments showed that the inhibition was not purely competitive. At low substrate concentrations, product inhibited the enzyme; at high substrate concentrations, the enzyme was first stimulated and then depressed by increasing levels of products. This behavior has been analyzed and shown to be possibly a result of the information of a tertiary intermediate produced during the reaction.
High‐yield method for immobilization of enzymes
Authors: Wasserman Bruce P. , Hultin Herbert O. , Jacobson Bruce S. 
Published: December 2004

AbstractTwo types of polyethylenimine‐coated glass microbeads (13–44 μm) were synthesized and used for the immobilization of glucose oxidase from Aspergillus niger and catalase from A. niger and beef liver. The two types of beads were distinguishable by differences in their surface topography. Immobilizations were performed by adsorption followed by treatment with glutaraldehyde. The immobilized‐enzyme activities per unit support of all of the enzymes tested were compared with and found to be superior to the immobilized activities attainable on aminopropyl‐activated glass microbeads. When enzyme was present in less than saturating amounts, the coated beads were able to remove 100% of the glucose oxidase activity initially present in the immobilization solution, with 78–87% of that activity expressed on the support surface. Bound glucose oxidase was more stable to thermal inactivation than native enzyme.
Growth kinetics under adenine‐limiting conditions of Bacillus subtilis KYA 741, an adenine‐requiring strain
Authors: Tsuchiya Katsumi , Kimura Tetsu , Okazaki Mitsuo , Miura Yoshiharu 
Published: December 2004

AbstractThe growth kinetics of Bacillus subtilis KYA 741, an adenine‐requiring strain, was investigated under adenine‐limiting conditions. The concentration of adenine (the limiting substrate for cell growth) in the culture filtrate remained constant during the stationary phase. In this phase, DNA turnover was active and the DNA content per cell was constant throughout the cultivation period. When cells were transferred to medium without adenine, the cell concentration began to decrease immediately and then reached a constant level due to the supply of adenine from lysing to growing cells. The rates of degradation of cells and DNA were both found to be 0.2 hr−1. An equation for cell growth in this pseudostationary phase was obtained by combining Contois' equation, in which the apparent saturation constant was a function of the cell concentration, with a term for cell degradation. This equation satisfactorily expressed the feature of cell growth and adenine consumption by B. subtilis KYA 741 under adenine‐limiting conditions.
Optimization of the production of progesterone 11α‐hydroxylase by Rhizopus nigricans
Authors: Hanish W. H. , Dunnill P. , Lilly M. D. 
Published: December 2004

AbstractThe progesterone 11α‐hydroxylase of Rhizopus nigricans ATCC 6227b is an inducible enzyme system that is primarily induced by its substrate progesterone. Maximum induction was found at a progesterone concentration of 0.5 g/liter or above. Oxygen is the other substrate for the hydroxylation and this was found to have a major effect on the amounts of hydroxylase synthesized. Optimum induction of the hydroxylase in a fermentation with a 3.1 m/sec impeller tip speed was found to occur at a dissolved oxygen tension (DOT) of 10% of air saturation. The agitation rate also effects the amount of hydroxylase synthesized with an apparent maximum at 3.1 m/sec impeller tip speed. The DOT for a maximum hydroxylation rate was much higher than for enzyme synthesis so that it was preferable to increase the DOT after induction was completed.
Growth of yeast on n‐alkanes. II. Batch experiments
Authors: Verkooyen A. H. M. , Rietema K. 
Published: December 2004

AbstractIn this paper the results of the Monte Carlo simulations as described in an earlier paper are compared with those of batch experiments. A number of batch experiments were carried out at a low inoculation rate so that only a fraction of the oil drops were inoculated. Under these conditions the effect of the segregation of the oil phase is more clearly demonstrated. Special attention is paid to the preparation of actively growing yeast cells with which the cultures is inoculated. Also a method is developed to estimate the amount of actively growing cells with which the culture is inoculated. The other parameters necessary for the Monte Carlo simulation are measured in separate experiments: the maximum growth rate of the cells, oil drop size, and the drop parameters. Finally the growth curves (measured in the batch experiments) are compared with those calculated with the Monte Carlo procedure. A good agreement is found.
Purification and properties of glucose isomerase of Actinoplanes missouriensis
Authors: Gong Cheng‐Shung , Chen Li Fu , Tsao George T. 
Published: December 2004

AbstractActinoplanes missouriensis produces an intracellular soluble glucose Isomerase. The soluble enzyme can be purified by a DEAE‐cellulose beads columm with a onestep salt elution. The purified enyzme exhibited a molecular weight of approximately 80,000 daltons, being composed of two identical subunits of about 42,000 daltons each. The Km for glucose is 1.33M, the Km for frucotse is 1.67M. The enzyme has an optimal pH of 7.0. The presence of the cobalt ion is not required to produce optimal activity of the enzyme if the proper amount of magnesium is present.
Chelating, film‐forming, and coagulating ability of the chitosan–glucan complex from Aspergillus niger industrial wastes
Authors: Muzzarelli Riccardo A. A. , Tanfani Fabio , Scarpini Gianfranco 
Published: December 2004

AbstractWaste mycelia of Aspergillus niger from a citric acid production plant are simply treated with boiling 30–40% NaOH aqueous solutions for 4–6 hr to obtain the insoluble chitosan‐glucan complex whose infrared, ESR, and x‐ray diffraction spectra are reported. A number of transition‐ and post‐transition‐metal are chelated and collected by chitosan‐glucan with higher yields than by animal chitosan. Immediate flocculation occur upon mixing chitosan‐glucan dispersions with alginate and polymolybdate solutions. Membranes are also obtained from chitosan–glucan dispersions in acetic acid or in chloral and dimethyl formamide mixtures.
Staining method for determination of the penetration of immobilized enzyme into a porous support
Authors: Carleysmith S. W. , Eames M. B. L. , Lilly M. D. 
Published: December 2004

AbstractThe penetration of bovine serum albumin and penicillin acylase into Amberlite XAD7 beads was determined by staining split beads. The rates of penetration were measured and correlated with a theoretically derived equation.
Purification and immobilization of Aspergillus niger β‐xylosidase
Authors: Oguntimein Gbekeloluwa B. , Reilly Peter J. 
Published: December 2004

Abstractβ‐Xylosidase from a commercial Aspergillus niger preparation was purified by differential ammonium sulfate precipitation and either gel permeation or cation exchange chromatography, giving 16‐fold purification in 32% yield for the first technique or 27‐fold purification in 19% yield for the second. The second method in addition almost completely removed interfering β‐glucosidase activity. Enzymes prepared by this method was immobilized to 10 different carriers, but only when it was bound to alumina with TiCl4 and to alkylamine porous silica with glutaraldehyde were substantial efficiencies and stabilities achieved. With alumina, the variation of activation procedure, amount of β‐xylosidase offered, and activation solution composition yielded maximum activities of over 40 U/g with approximately 70% immobilization efficiency. Variation of binding pH and incubation time led to a maximum immobilized activity of 1.3 U/g with 78% immobilization efficiency on silica.
Batch and multistage continuous ethanol fermentation of cellulose hydrolysate and optimum design of fermentor by graphical analysis
Authors: Tyagi R. D. , Ghose T. K. 
Published: December 2004

AbstractBatch and single‐flow four‐stage continuous ethanol fermentations of bagasse hydrolysate have been investigated at pH 4.0 and 30°C with a strain of the yeast Saccharomyces cerevisiae. The studies were carried out in the laboratory four‐stage cascade continuous stirred‐tank fermentors at varying feed glucose concentrations (10, 14, 18, and 22%). The range of dilution rates employed varied from 0.05 to 0.2 hr−1. The hydrolysate was supplemented with a cheap nitrogen source (CNS), CaCl2·H2O and MgSO4·7H2O. A 2% (v/v) CNS concentration was found to be sufficient to avoid growth limitation at a glucose concentration of 116 g/liter. The conditions of continuous culture in a multistage system are predicted by a graphical method based on batch‐culture data. The results thus obtained are compared with those predicted by kinetic models and with the experimental results. The variations between the results obtained experimentally and those computed either by a kinetic model or by graphical analyses were found to be within the limits of experimental error. The solutions based on the concept of minimum residence time necessary to achieve the desired biomass or product concentrations are also discussed.
The Brazilian ethanol program
Authors: Pimentel Luiz Straunard 
Published: December 2004

AbstractBrazilian needs for petroleum as a primary energy source grew from 13.2% in 1940 to 41.7% in 1977. This resulted in a much greater dependence on foreign sources and prompted the Government to initiate a detailed study of alternatives. The National Alcohol Program established in 1975 is just one of the options being examined. The National Energy Balance forecast shows that annual anhydrous alcohol consumption for automotive purposes should increase from 1.74 × 106m3 to 4.7 × 106 m3 in the period from 1978 to 1987. This paper presents the main objectives of the National Alcohol Program in the context of the overall Energy Program, points out the problems connected with alcohol production and utilization, and reviews the serious problems related to its distribution to the consuming centers. Finally, the indirect benefits resulting from the implementation of the National Alcohol Program are shown, underlining the saving of foreign currency, the substantial increase in employment opportunities, the reduction in regional and individual income discrepancies, and the expansion of capital goods production, together with the improvement of national technology in the agricultural and industrial sectors.
Characteristics of immobilized invertase
Authors: Ooshima Hiroshi , Sakimoto Masuo , Harano Yoshio 
Published: December 2004

AbstractFive kinds of immobilized invertases (IMI)—covalently of porous glass and ion‐exchange resins and ionically on ion‐exchange resins—have been prepared and their kinetic characteristics for sucrose hydrolysis, such as Km, K, pH profile, and thermal stability were studied. Comparing the values of Km and activation energy and the entropy of IMI with those of native invertase, it was concluded that the immobilization influences not binding but kinetic specificity. The effects of the immobilization method on thermal stability were also discussed.
Immobilized catalase‐containing yeast cells: Preparation and enzymatic properties
Authors: D'Souza S. F. , Nadkarni G. B. 
Published: December 2004

AbstractThe cell of Saccharomyces cerevisiae previously induced for catalase (EC 1.11.1.6) activity were immobilized by entrapment of intact cells in acrylamide polymerized by γ irradiation (100 kR). Yeast cells showed an enhancement in catalase activity on entrapment, an effect similar to that observed on treatment with organic solvents like toluene. The cells pretreated with toluene, however, showed complete loss of catalase activity on entrapment. The entrapped enzyme exhibited a narrow pH optimum, reduced Km for H2O2, and a decrease in thermostability. The temperature optimum of catalase was also decreased from 60 to 40°C on immobilization. A tenfold decrease in the activation energy was also observed. The enzyme in the entrapped cells was, however, stable toward inactivation by γ irradiation. Unlike the intact cells, the entrapped yeast cells did not have the ability to induce catalase.
Increased production of cellulase of Trichoderma sp. by pH cycling and temperature profiling
Authors: Mukhopadhyay S. N. , Malik R. K. 
Published: December 2004

AbstractCultivation of Trichoderma reesei QM 9414 on 3% (w/v) cellulose medium (C/N ratio = 8.5) produced 4.5 IU/ml celulase 180 hr at a cell growth of 8.0 g/liter (0.266 g cell/g cellulose). It corresponded to an average cellulase productivity 25.0 IU/liter/hr (3.5 IU/g cell/hr). In the same medium 9.5 g/liter cell mass (0.316 g cell/g cellulose), 6.2 IU/ml cellulase, and 38.75 IU/liter/hr (4.0 IU/g cell/hr) cellulase productivity could be obtained using pH cycling condition during cultivation. Cell mass, cellulase yield, and productivity were further increased to 10.0 g/liter, 7.2 IU/ml, and 44.0 IU/liter/hr (4.5 IU/g cell/hr), respectively, by simultaneous pH cycling and temperature profiling strategy. Results are described.
Modified kit procedure for the kinetic assay of ethanol
Authors: Bostick William D. , Overton James B. 
Published: December 2004

AbstractWe have examined the utility of a commercial kit procedure for the determination of ethanol (EtOH), based upon its enzymatic oxidation and the concurrent production of NADH, monitored by photometry at 340 nm. We found that the equilibrium production of NADH is not stoichiometric with respect to initial ethanol concentration, and that with this procedure, the calibration curve for end‐point assay of ethanol is linear only for very dilute solutions. Likewise, the kinetic assay of ethanol using the kit procedure is limited to very dilute samples (i.e., concentration in the reaction mixture of ⩽2.3 mg EtOH/liter). We describe a simple modification of the kit procedure which makes it amenable to the precise kinetic assay of up to 150 mg EtOH/liter in the reaction mixture. This increase in the dynamic range for kinetic assay of ethanol results form the use of hydrazine both as a trapping agent for the acetaldehyde reaction product and as a competitive inhibitor of alcohol dehydrogenase enzyme.
Growth yield from electrons available from substrates in aerobic‐ and photoheterotrophic cultures of Rhodopseudomonas sphaeroides S
Authors: Sasaki Ken , Nishizawa Yoshinori , Nagai Shiro 
Published: December 2004

AbstractA balance of electrons available from acetic acid consumed for growth and oxygen uptake in the aerobic‐ and photoheterotrophic growth of Rhodopseudomonas sphaeroides S on acetate‐minimal medium could be realized the same as in the carbon balance. The unmeasured amounts of yeast extract consumed by the cells grown on propionate–yeast extract media were indirectly estimated from the balance equation of electrons available from carbon substrates. The specific consumption rate of the yeast extract increased with an increase in propionate consumption rate in aerobic and photoheterotrophic cultures. Growth yields from acetic acid and from propionic acid plus yeast extract were calculated on the electron level, i.e., YX/ave g cell produced/equivalent electrons available from substrate consumed. YX/ave values were 5.0 to 5.8 g cell/ave in photoheterotrophic cultures and 2.7 to 3.6 in aerobic–heterotrophic cultures regardless of different medium compositions.
Design of a fast flow reactor for aerobic treatment of dilute waste streams
Authors: Kristiansen B. , Bu'Lock J. D. 
Published: December 2004

AbstractThe design of a 125 liter aerated recirculating tower fermentor is presented. The tower has an external recirculation loop and a broth take‐off point designed to give selective retention of biomass in the fermentor. This allows operation with high throughput rates using a low conentration feed. The aspect ratio in the main tower is approximately 14:1, but good mixing is promoted by the rapid recirculation of the broth. The construction of the fermentor and costs are given in details, illustrating that the fermentor may offer a cheap alternative to conventional systems.
Some observations on immobilized hydrogen‐producing bacteria: Behavior of hydrogen in gel membranes
Authors: Matsunaga Tadashi , Karube Isao , Suzuki Shuichi 
Published: December 2004

AbstractA hydrogen‐producing bacterium, Clostridium butyricum, was immobilized in polyacrylamide gel membrane, agar gel membrane, and collagen membrane. The apparatus consisted of a compartment(I or II) and a whole‐cell‐entrapped gel membrane which was placed in the center of the two compartments. The behavior of hydrogen through whole‐cell‐entrapped gel membrane was examined for improving the sensitivity of a microbial BOD sensor and the efficiency of biochemical fuel cells. The bacteria‐polyacrylamide gel membrane produced a higher amount of hydrogen in compartment II than the other bacteria‐entrapped gel membranes. The apparent diffusion constant decreased with increasing bacteria contents in the gel membrane. As a result, 100 mg wet cells/g gel was the maximal bacteria content in the membrane for the production of hydrogen. Twenty percent of the hydrogen evolved by the whole cells diffused to compartment II, and there was a linear relationship between the glucose concentration in a bulk solution (compartment I) and the rate of hydrogen diffused to compartment II.
Kinetic study of a membrane enzyme reactor
Authors: Kitano H. , Yoshijima S. , Hotogi S. , Ise N. 
Published: December 2004

AbstractA flat‐membrane dialyzer was used as enzyme reactor by introducing enzyme solution into one of the membrane‐separated chambers. The apparent Michaelis constant Km(app) of urease was always larger (ten times at [urease] = 1 mg/ml) than that of free enzyme because the permeation of substrate through the membrane was rate determining. Km(app) for urease decreased from 125 to 20mM with increasing flow rate of the substrate solution because of the turbulent flow near the membrane. In the case of glucose oxidase or creatine kinase, the reaction rate was limited by the permeation of less permeable substrates such as oxygen or ATP. Therefore, Km(app) of more permeable substrates such as glucose or creatine became smaller than that of free enzyme. The reaction amount calculated from the permeation data agreed well with experimental results. By designing spacers for the reactor to give turbulence to the solution, the effectiveness of the reactor was improved fivefold.
Photochemical system for regenerating NADPH from NADP with use of immobilized chloroplasts
Authors: Karube Isao , Otsuka Toshiaki , Kayano Hiromichi , Matsunaga Tadashi , Suzuki Shuichi 
Published: December 2004

AbstractSpinach chloroplasts were immobilized in 2% agar gel. Crude ferredoxin and NADP–ferredoxin oxidoreductase isolated from spinach were used as electron carriers. The activity of the NADP reduction by immobilized chloroplasts increased with increasing ferredoxin concentration and the maximum activity was obtained at 8μM ferredoxin. The saturation of NADP reduction was observed at a light intensity of over 1000 lx. The optimum pH and temperature of NADP reduction were 8 and 25°C, respectively. The reduced NADP in a reaction medium increased linearly with increasing reaction time under illumination. NADP was continuously reduced for 2 hr with a hollow‐fiber reactor containing immobilized chloroplasts. NADPH and NADP were separated with a hollow‐fiber dialyzer from ferredoxin and NADP–ferredoxin oxidoreductase, which were reused. The conversion ratio of NADP to NADPH was from 40 to 80%.
Enzyme activity maintenance in packed‐bed reactors via continuous enzyme addition
Authors: Verhoff F. H. , Schlager S. T. 
Published: December 2004

AbstractAn operational scheme for using immobilized enzymes in packed‐bed reactors that permits operation at a constant throughput rate and constant product quality is described. The scheme used columns operated in series with continuous enzyme addition to compensate for enzyme decay. A mathematical technique was developed to determine the enzyme addition rate, enzyme usage, and enzyme volume in the column system. Operation of columns in series is compared to operation where the flow rate is decreased to compensate for a loss of enzyme activity for both zero‐and first‐order decay. The analyses indicated that columns in series resulted in better enzyme utilization but larger reactor volumes than parallel reactors with decreasing flow rate.
Estimation of intrinsic kinetic constants for pore diffusion‐limited immobilized enzyme reactions
Authors: Lee Gene K. , Lesch Robert A. , Reilly Peter J. 
Published: December 2004

AbstractA simple method is presented that establishes intrinsic rate parameters when slow pore diffusion of substrate limits immobilized enzyme reactions that obey Michaelis‐Menten kinetics. The Aris‐Bischoff modulus is employed. Data at high substrate concentrations, where the enzyme would be saturated in the absence of diffusion limitation, and at low substrate concentrations, where effectiveness factors are inversely proportional to reaction modulus, are used to determine maximum rate and Michaelis constant, respectively. Because Michaelis‐Menten and Langmuir‐Hinshelwood kinetics are formally identical, this method may be used to estimate intrinsic rate parameters of many heterogeneous catalysts. The technique is demonstrated using experimental data from the hydrolysis of maize dextrin with diffusion‐limited immobilized glucoamylase. This system yields a Michaelis constant of 0.14%, compared to 0.11% for soluble glucoamylase and 0.24% for immobilized glucoamylase free of diffusional effects.
Application of microbial cells as multistep catalysts in potentiometric biosensing electrodes
Authors: Kobos R. K. , Pyon H. Y. 
Published: December 2004

AbstractThe advantages of using intact microbial cells to mediate complex reaction sequences in the construction of biosensing electrodes are domonstrated. A potentiometric sensor was developed for nitrilotriacetic acid (NTA) in which a strain of Pseudomonas sp. was coupled to an ammonia gas‐sensing electrode. the bacterial cells carry out a four‐step reaction sequence to produce the measured species, ammonia, from NTA. The resulting microbial electrode responded to NTA in the concentration range of 1 × 10−4 M to 7 × 10−4M, with a slope of 35‐40 mV/decade. The electrode was stable for up to one month.