bluuebunny/crossref_metadata_2025_split huggingface dataset:
YATP value in Candida tropicalis grown on n‐alkanes, fatty acids, and acetate
Authors: Gallo Michel , Azoulay Edgard 
Published: December 2004

AbstractThe amount of ATP produced during n‐alkane, fatty acid, or acetate metabolism in Candida tropicalis has been established from the P/O ratios measured on isolated mitochondria, yield on substrate andcarbon balance. For these three kinds of substrates, YATP value has been found to be close to 4, although Ysub on acetate is very different from those found with n‐alkanes or fatty acids.
Performance of affinity chromatography columns
Authors: Katoh Shigeo , Kambayashi Tomio , Deguchi Ryuichi , Yoshida Fumitake 
Published: December 2004

AbstractPerformance of affinity chromatography columns was studied by measuring the rates of adsorption and elution of trypsin in a Sepharose 4B‐soybean trypsin inhibitor column and a Sepharose 4B‐arginine peptides column. The volumetric coefficient for trypsin transfer was evaluated from the break‐through curves of trypsin, and elution profiles bed height of Sepharose 4B‐STI column was estimated based on these results.
Chemical flocculability of sludge organisms in response to growth conditions
Authors: Wu Yeun C. 
Published: December 2004

AbstractThe effect of waste characteristics on the removal of suspended solids and soluble phosphorus by alum, Al2(SO4)3·18H2O, was investigated in an activated sludge system with no cellular recycle. Under the conditions presently studied, it was found that sludge organisms grown in nitrogen‐ and phosphorus‐restricted media possess exceptionally large capsules and produce a higher surface electric charge per unit of fry weight. Chemical demand for separation of these capsulated cells is obviously higher than those solids cultivated under a well‐balanced nutrient condition. For phosphorus removal, the molar ratio of Al+3:P is a function of the initial concentrations of soluble phosphorus and suspended solids in solution. The relationship between percent phosphorus removal and the quantity of chemical coagulent used shows nonstoichiometric relationship; that is, the required molar ratio of Al+3:P is always greater than one and directly depends upon the content of suspended solids in the flocculated media. Moreover, the present study indicated that chemical separation of dispersed microorganisms occurred following phosphorus removal.
Mycelial paper: A potential resource recovery process?
Authors: Johnson Morris A. , Carlson John A. 
Published: December 2004

AbstractEleven species of fungi representative of a broad range of cell‐wall compositions were evaluated with respect to their papermaking potential as additives to woodpulp furnishes. Some of these species were also examined for their ability to grow on a spent liquor from the pulp‐and‐paper industry. Handsheets with various levels of incorporated mycelia exhibited a wide range of species‐dependent properties. Behavior of the mycelia in the sheets can be modified to a degree by physical and chemical treatments. The overall results suggest that small amounts (5–10% of the sheet constituents) of mycelia, grown inexpensively on waste effluents, might be incorporated into wood fiber paper without serious deleterious effects on paper strength properties. In some cases improved paper is obtained, and larger quantities of mycelia might be used to impart specific properties to the product.
Applications of purification reactions for minimizing reaction‐generated enzyme poisoniong
Authors: Yeung Simon Y. S. , Cho Yong K. , Bailey James E. 
Published: December 2004

AbstractA mathematical model has been employed to examine the interplay of reaction and mass transfer in immobilized enzyme systems involving reaction‐generated enzyme poisons. Deactivation rates can be significantly reduced in some cases by catalyzing a purification reaction in which the poison is transformed into an innocuous substance. This conclusion is illustrated experimentally for reaction‐generated H2O2 in a continuous‐flow stirred slurry reactor containing glucose oxidase immobilized on activated carbon.
Steroid transformation by activated living immobilized Arthrobacter simplex cells
Authors: Ohlson S. , Larsson P. O. , Mosbach K. 
Published: December 2004

AbstractA preparation of living Arthrobacter simplex cells immobilized in polyacrylamide gel, which showed steroid‐Δ1‐dehydrogenase activity, was studied. The entrapped microorganisms catalyzed the transformation of cortisol to prednisolone and this reaction was followed spectrophotometrically or with the aid of thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC). About 40% of the original activity found with free bacteria was retained after immobilization. The steroid dehydrogenase activity of polyacrylamide‐entrapped A. simplex could be raised to a minor extent in alcoholic solvents or by addition of a cofactor such as menadione. On incubation in various nutrient media, on the other hand, the activity could be increased considerablyl, usually 7–10 times. Possible causes for the observed increase in activity have been investigated, and microbial growth of the original entrapped microorganisms appears to be the major reason. Frozen activated preparations of immobilized A. simplex showed only a small loss of activity on storage for at least four months. A semicontinuous batch wise operation with immobilized A. simplex in different nutrient media was carried out. At the end of the experiment the steroid transformation capacity was 0.5 g steroid per day per g gel (wet weight).
Immobilization of amyloglucosidase on poly [(glycidyl methacrylate) Co(ethylene dimethacrylate)] carrier and its derivatives
Authors: Švec F. , Kálal J. , Menyailova I. I. , Nakhapetyan L. A. 
Published: December 2004

AbstractImmobilization of amyloglucosidase (EC 3.2.1.3) from Endomycopsis bispora and Aspergillus niger was followed with carriers containing epoxide, aldehyde, and primary amino groups. Determinations of stability of bound enzyme showed that the most active and stable preparations were obtained by application of the carrier with amino groups activated with glutaraldehyde (activity half‐life 96.6 days). Optimum pH and and temperature were found for cleavage of starch solution and KM(app) and Vmax(app) values were determined for all prepared samples.
Maintenance requirements for bacteria growing on C1‐compounds
Authors: Rokem (Rock) J. S. , Goldberg I. , Mateles R. I. 
Published: December 2004

AbstractThe maintenance coefficient, ms (mmol substrate/g cell dry wt hr), of two distinct groups of C1‐utilizing bacteria has been determined by growing the organisms in an aerobic continuous culture limited by different C1 growth substrates. For growth on methanol, ms = 2.5 ± 0.3 for Pseudomonas C; 3.9 ± 0.7 for Ps. methylotropha (these bacteria utilize methanol via the ribulose monophosphate pathway of formaldehyde fixation) 1.5 ± 0.2 for Pseudomonas 1, and 2.3 ± 0.4 for Pseudomonas 135 (the latter bacteria utilize C1‐compounds via the serine pathway). For growth on formaldehyde, ms = 1.5 ± 0.3 for Pseudomonas 1 and 2.7 ± 0.7 for Pseudomonas 135, whereas on formate the values for ms are 1.0 ± 0.2 and 4.4 ± 1.3; respectively. Although the maintenance coefficients did not differ systematically between the two groups of bacteria, the maintenance requirements per generation of the serine pathway bacteria were considerably higher (8.7 vs. 3.9) owing to their slower growth rate. The maximum molar yield values, YMmax (g cell dry wt/mol substrate utilized), corrected for the maintenance energy of bacteria which utilize C1‐compounds via the ribulose monophosphate pathway averged 10.1 when grown on methanol, while the values for bacteria which use the serine pathway averaged 13.5. On formaldehyde an average value of 11.5 is obtained and on formate the average value was 7.4 in the serine pathway bacteria.
Application of mass and energy balance regularities in fermentation
Authors: Erickson L. E. , Minkevich I. G. , Eroshin V. K. 
Published: December 2004

AbstractMaterial and energy balances for fermentation processes are developed based on the facts that the heat of reaction per electron transferred to oxygen for a wide variety of organic molecules, the number of available electrons per carbon atom in biomass, and the weight fraction carbon in biomass are relatively constant. Mass–energy balance equations are developed which relate the biomass energetic yield coefficient to sets of variables which may be determined experimentally. Organic substrate consumption, biomass production, oxygen consumption, carbon dioxide production, heat evolution, and nitrogen consumption are considered as measured variables. Application of the balances using direct and indirect methods of yield coefficient estimation is illustrated using experimental results from the literature. Product formation is included in the balance equations and the effect of product formation on biomass yield estimates is examined. Application of mass–energy balances in the optimal operation of continuous single‐cell protein production facilities is examined, and the variation of optimal operating conditions with changes in yield are illustrated for methanol as organic substrate.
Modeling the role of cyclic AMP in catabolite repression of inducible enzyme biosynthesis in mircobial cells
Authors: Gondo Shinichiro , Venkatasubramanian K. , Vieth Wolf R. , Constantinides A. 
Published: December 2004

AbstractModeling the role of cyclic AMP (cAMP) in catabolite repression of inducible enzyme production in microbial cells was studied. A catabolite repression index, F, was defined based on the postulation that complex formation occurs between RNA polymerase (RNAP) and DNA, and shifting from the inert form to the open form of this complex (the latter form is required for transcription) is accelerated by the cAMP·CRP complex. The catabolite repression index, F, was incorporated into model equations of mRNA production. Empirical relationship between intracellular cAMP level and medium glucose concentration were established based on experimental data and introduced into the model. Computer simulation results were obtained for a number of interesting cases. The practical utility of the proposed model was demonstrated by comparing it with the experimental results on glucose isomerase biosynthesis.
Diffusional influences on the parametric sensitivity of immobilized enzyme catalysts
Authors: Karanth N. G. , Bailey J. E. 
Published: December 2004

AbstractImmobilization of an enzyme within an insoluble material permeable to substrate can change the apparent behavior of the enzyme. In particular, external mass transfer and intraparticle diffusion effects can significantly influence the dependence of observed reaction rate on operating parameters such as temperature and pH. This analysis shows that, under very general conditions, the influence of diffusion alone is to diminish the sensitivity of the observed rate to any parameter that is uniform throughout the catalyst particle. However, the optimal value of the parameter is not changed because of intrapellet diffusional effects.
Comparison of maximum cell yield and maintenance coefficients in axenic cultures and activated sludge communities
Authors: Pipyn P. , Verstraete W. 
Published: December 2004

AbstractComparison of the equations that describe the relationship between the maximum cell yield coefficient, the maintenance coefficient, and the specific growth rate at steady‐state conditions revealed that the equations used for axenic cultures are congruent with those commonly used for mixed‐culture system such as activated sludge. A unified basis was proposed. The expression of the yield and maintenance coefficients in carbon units according to the unified basis permitted one to evaluate literature data on both axenic and mixed‐culture systems. From this it appears that the maximum cell yield ranges from 0.50–0.80 (mg biomass carbon formed/mg substrate carbon used) for both axenic and mixed systems. However, the maintenance coefficient (mg substrate C/mg biomass C·hr) for the axenic cultures was between 0.010 and 0.100, but for activated sludge communities it was between 0.001 and 0.010. Microorganisms were isolated from sludge communities with these apparently low maintenance requirements and grown axenilly. Their maintenance coefficients but not their maximum yield coefficients decreased with decreasing specific growth rates. The consequences of this finding with regard to species selection in mixed‐culture systems and the concept of cellular maintenance requirement are discussed.
Immobilization of Streptomyces phaerochromogenes by radiation‐induced polymerization of glass‐forming monomers
Authors: Kumakura Minoru , Yoshida Masaru , Kaetsu Isao 
Published: December 2004

AbstractImmobilization of Streptomyces phaerochromogenes was radiation induced polymerization of 2‐hydroxylate at low temperatures. Radiation damage of the enzyme could be avoided by choosing irradiation at low temperatures. The enzymatic activity of immobilized cells increased remarkably with a decrease in the irradiation temperature of about −24°C. In constrast to the case of cell‐free enzyme immobilization, the most characteristic case was that in these immobilized cells, the enzymatic activity did not decrease with repeated use even in the composite obtained at much lower monomer concentrations. Another characteristic of immobilized cells was the increase in enzymatic activity in the initial stage of repeated use, which could be attributed to the swelling effect of the polymer matrix, thereby increasing the enzymatic activity to whole cells.
Energetic efficiency of biomass and product formation
Authors: Erickson L. E. 
Published: December 2004

AbstractEquations are developed that may be used to estimate the energetic efficiency of biomass production and product formation when organic substrate consumption is used for growth, maintenance, and product formation. Regularities are utilized to develop balance equations with which the energetic efficiencies of biomass production and product formation may be estimated using several different sets of measured variables. The theory is illustrated by considering the growth in continuous culture of Aspergillus nidulans, which produces melanin.
Enzyme immobilization techniques on poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) carrier with penicillin amidase as model
Authors: Drobník J. , Saudek V. , Švec F. , Kálal J. , Vojtíšek V. , Bárta M. 
Published: December 2004

AbstractTwo types of bead‐form macroporous carriers based on glycidyl methacrylate with ethylene dimethacrylate copolymers were used for the immobilization of penicillin amidase either directly or after chemical modificaton. Direct binding through oxirane groups, which is equally efficient at pH 4.2 and 7, is relatively slow and brings about an activity loss at low enzyme concentrations. The most efficient immobilization was achieved on glutaraldehyde‐activated amino carier, irrespective of whether the amino groups were formed by ammonia or 1,6‐diaminohexane treatment of the original oxirane carrier. Hydrazine treatment gave lower immobilization yields. The same is true of the azide method independent of the length of the spacer. Most enzyme activity was preserved by coupling the carbodiimide‐activated enzyme to the carrier with alkyl or arylamino groups at the end of a longer substituent. Immobilization on diazo‐modified carrier gave average results. Rapid immobilization by a lysine‐modified phosgene‐treated carrier resulted in an activity loss. It is suggested that multipoint and very tight attachment of the enzyme molecule to the matrix decreased the activity. The immobilized activity is quite stable in solution and very stable upon lyophilization with sucrose.
Microbial electrode sensor for alcohols
Authors: Hikuma Motohiko , Kubo Tatsuru , Yasuda Takeo , Karube Isao , Suzuki Shuichi 
Published: December 2004

AbstractA microbial electrode consisting of immobilized microorganisms, a gas permeable Teflon membrane, and an oxygen electrode was prepared for the continuous determination of methyl and ethyl alcohols. Immobilized Trichosporon brassicae was employed for a microbial electrode sensor for ethyl alcohol. When a sample solution containing ethyl alcohol was injected into a microbial electrode system, the current of the electrode decreased markedly with time until a steady state was reached. The response time was within 10 min by the steady state method and within 6 min by the pulse method. A linear relationship was observed between the current decrease and the concentration of ethyl alcohol below 22.5 mg/liter. The current was reproducible within ± 6% of the relative error when a sample solution containing 16.5 mg/liter ethyl alcohol. The standard deviation was 0.5 mg/liter in 40 experiments. The selectivity of the microbial electrode sensor for ethyl alcohol was satisfactory. The microbial electrode sensor was applied to a fermentation broth of yeasts and satisfactory comparative results were obtained (correlation coefficient 0.98). The current output of the microbial electrode sensor was almost constant for more than three weeks and 2100 assays. A microbial electrode sensor using immobilized bacteria for methyl alcohol was also described.
Feedback control of a competitive mixed‐culture system
Authors: Wilder Carl T. , Cadman Theodore W. , Hatch Randolph T. 
Published: December 2004

AbstractThree feedback strategies for the on‐line control of cell densities in a mixed‐culture system have been examined. A competitive mixed‐culture system of Candida utilis and Corynebacterium glutamicum grown on glucose as the limiting carbon source was modeled using Monod growth kinetics. First‐order time constants were added to simulate transient growth effects. Multivariable feedback control of cell densities by manipulation of substrate feed and dilution rate was investigated. Feedback strategies directed to minimizing control interactions were found to be superior to classical feedback. Transients in the growth‐rate response produced oscillations in cell density and required retuning of control constants. The relative time constants of the two species were important, with the largest oscillations resulting when the faster growing organism had the faster time constant.
Model of growth and ergot alkaloid production by Claviceps purpurea
Authors: Grm B. , Mele M. , Kremser M. 
Published: December 2004

AbstractA growth model for Claviceps purpurea in submerged batch culture is presented. In developing the model, the basic principles of the growth and the morphological properties of C. purpurea are considered. The growth of C. purpurea is assumed to occur in a three‐step manner; the first step involves the assimilation and the growth of cells; the second one involves cell division, and the third one involves transformation of the mature cells to a state where they have no ability to divide but do have the ability to produce ergot alkaloids and then they gradually die. Inorganic phosphate is assumed to be the limiting substrate for the first and the second steps in conditions of carbon source being in excess. The model constants are determined by model simulation and graphical searching techniques to find the minimum value of the absolute difference between the experimental and the simulated curves for biomass, alkaloids, and sucrose.
Temperature and pH dependence of mold α‐galactosidase
Authors: Kobayashi Harumi , Suzuki Hideo 
Published: December 2004

AbstractThe effect of temperature and pH on kinetic behavior of α‐galactosidase of Mortierella vinacea was investigated on the hydrolysis of p‐nitrophenyl‐α‐D‐galactopyranoside (PNPG). A very unusual kinetic behavior was observed for the soluble α‐galactosidase i.e., substrate inhibition diminished gradually with increasing temperature or near the neutral pH range, and the kinetics approached the ordinary Michaelis‐Menten (MM) type. On the other hand, with decreasing temperature or in acidic pH range, substrate inhibition was accelerated. Therefore, Arrhenius plots based on the initial reaction rate did not give straight lines. Furthermore, the slope in the Arrhenius plot changed with substrate concentration, which would make the determination of a characteristic value using conventional methods meaningless. However, the Arrhenius plots of individual kinetic parameters in the rate equation resulted in straight lines in the temperature range 15 to 50°C. From this, the drastic change in kinetic behavior could be explained in connection with the temperature and pH dependence of kinetic parameters in the model. For mold pellets (whole‐cell enzyme), however, the influence of temperature and pH was less apparent than that of soluble enzyme because of the limitation in intraparticle diffusion. By using the rate equation that was determined for soluble enzyme and the theoretically derived effectiveness factor, the overall reaction rate for mold pellets at various temperature and pH could be predicted to some extent.
Growth of yeast on n‐alkanes. I. Stochastic model
Authors: Verkooyen A. H. M. , Rietema K. 
Published: December 2004

AbstractIn a system where yeast cells grow on n‐alkanes dissolved in oil drops suspended in water, the dispersed oil phase will, in most cases, be fully segregated. This means that each drop has its own history that depends on its degree of saturation with yeast cells. This degree of saturation with yeast cells is determined by a stochastic process depending on adsorption, desorption, and cell production. Although many authors mention segregation as a phenomenon likely to occur, so far this segregation has hardly been taken into account. In this paper the interaction of the population of completely segregated oil drops with the population of yeast cells, which results in growth, is described. The consequences of the model are elucidated by the discussion of some extreme cases. The batch fermentation of hydrocarbons by yeast cell is simulated by means of a Monte Carlo procedure. Adsorption, desorption, and production of yeast cells are considered as chance processes. The history of all individual drops is recorder. The influence of the chance of desorption appears to be much larger than that of the chance of adsorption (at the investigated range). Also the size of the inoculum at the start of the process appears to have a strong influence on the course of fermentation.
Growth of yeast on n‐alkanes. II. Adsorption‐ desorption phenomena
Authors: Verkooyen A. H. M. , van den Oever A. H. C. , Rietema K. 
Published: December 2004

AbstractIn the stochastic as well as in other models that describe the growth of yeast on liquid hydrocarbons, the adsorption and desorption of cells to drops influence to a very great extent the growth rate of the cells. In this paper a method is presented and equipment is described by which it was possible to measure the cell‐drop interaction directly. While analyzing the results of these measurements it was found that the adsorption and desorption of cells are rather complicated processes. The size distribution of the oil drops is one of the parameters that has to be taken into account. The analysis of the results yields a fairly accurate value for the initial adsorption rate. Departing from a somewhat speculative description of the influence of drop size distribution on the adsorption rate, the order of magnitude of the desorption rate constant could be calculated.