bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of ammonium ion and extracellular pH on hybridoma cell metabolism and antibody production
Authors: McQueen Anne , Bailey James E. 
Published: December 2004

AbstractThe effects of NH4Cl addition on batch hybridoma cell growth at different external pH values (pHe) were investigated in a bioreactor at constant pH and dissolved oxygen concentration. In agreement with measurements in flasks, changes in pHe over the range 6.8–7.6 had minor effects on growth. Addition of 3 mM NH4Cl had little effect on cell growth while 10 mM NH4Cl caused a substantial growth inhibition, Measurements of the effects of pHe and NH4Cl concentration on cell metabolism gave similar results for cells grown in flasks in an incubator and in the bioreactor. As pHe decreases, the integral cell yield on glucose increases. There is a correlation between the effects of pHe on glycolysis and previous measurements of its effects on intracellular pH (pHi). Increases in NH4Cl concentration were previously determined to decrease pHi and are shown here to decrease the integral cell yield on glucose. At all pHe values in the absence of NH4Cl, glutamine is depleted at the time the maximum cell density is reached. Both pHe decreases and NH4Cl concentration increases lead to decreases in the integral cell yield on glutamine. Changes in pHe and in the NH4Cl concentration that cause growth inhibition have no effect on the specific antibody production rate for cells grown in flasks in an incubator or in the bioreactor. Changes in the NH4Cl concentration have no effect on the quality of the antibody produced, to a first level of characterization.
Production of S‐adenosyl‐L‐methionine by Saccharomyces cerevisiae cells carrying a gene for ethionine resistance
Authors: Shiomi Naofumi , Fukuda Hideki , Fukuda Yasuki , Murata Kousaku , Kimura Akira 
Published: December 2004

AbstractA gene for ethionine resistance isolated from the yeast Saccharomyces cerevisiae DKD‐5D‐H conferred on the yeast cells resistance to seleno‐L‐methionine and capability to produce S‐adenosyl‐L‐methionine in the cells. An enzymatic study of the L‐methionine synthetic pathway of L‐methionine proto‐ and auxotrophs and in dried yeast cells with or without the gene suggested that the cloned gene for ethionine resistance is responsible for the activity of S‐adenosyl‐L‐methionine synthase. To produce S‐adenosyl‐L‐methionine by yeast cells transformed with the ethionine resistance gene, some culturing conditions were determined.
Action pattern of alpha‐amylase from Aspergillus oryzae in concentrated media
Authors: Graber Marianne , Combes Didier 
Published: December 2004

AbstractThe influence of concentrated maltotetraose solutions on fungal alpha‐amylase activity and specificity has been determined. It has been found that the enzyme is not inhibited by 500 g/L substrate concentration and that transglycosylation reactions are increased with rising substrate concentration. The amount of oligosaccharides of polymerization degree higher than maltotetraose reaches 20% (w/w). Moreover, the effect of polyhydric alcohols, known as water activity depressors has been analyzed: the presence of polyols does not modify the amount of transglycosylation products, but changes the hydrolysis pattern by favoring the formation of low polymerization degree oligosaccharides.
Oscillatory behavior of Saccharomyces cerevisiae in continuous culture: II. Analysis of cell synchronization and metabolism
Authors: Chen Ching‐I , McDonald Karen A. 
Published: December 2004

AbstractSustained oscillations of biomass, ethanol, and ammonium concentrations, specific growth rate, and specific uptake rates of ethanol, ammonium, and oxygen were found in continuous cultures of Saccharomyces cerevisiae under controlled dissolved oxygen (DO), pH, and temperature conditions. The period of oscillations was approximately 2.5–3 h at a pH of 5.5 and 2–2.5 h at a pH of 6.5. Oscillations were observed only under conditions of low carbon (glucose below the minimum detectable level), nitrogen nutrient (ammonium concentration varied between 0.00001 and 0.0015M), and ethanol concentration (0.002–0.085 g/L) in the bioreactor.The oscillatory behavior at pH 5.5 was also characterized by partially synchronized cell growth and reproduction. Not only did the total percentage of budding cells oscillate with the same period as observed for the global biomass and nutrient concentrations, but the peaks in the individual subpopulations of initial budding, middle budding, and late budding cells appeared sequentially during the oscillation period. This provides strong evidence of the hypothesis that variations in metabolism during different periods in the cell cycle of a partially synchronized cell population are responsible for the observed oscillatory bioreactor behavior.The specific nutrient uptake rates for ammonium and oxygen as well as the net specific ethanol uptake rate oscillated with the same period as the biomass oscillations. These results show a dramatic increase in the ammonium and oxygen consumption rates prior to the initial budding of the synchronized subpopulation and a decrease in these rates during the late budding phase. At a pH of 5.5, the late budding phase is characterized by high specific ethanol productivity; however, the ethanol productivity lags the late budding phase at a pH pf 6.5. The observed time‐varying metabolism in the oscillatory operating regime appears to be the result of the metabolic changes which occur during the cell cycle. Models which can predict the oscillatory biomass concentration and nutrient levels in this regime must be capable of predicting the concentrations and metabolic rates of the subpopulations as well.
Production of L‐phenylacetyl carbinol by immobilized yeast cells: I. Batch fermentation
Authors: Mahmoud Wafaa M. , El‐Sayed Abdel‐Halima M. M. , Coughlin Robert W. 
Published: December 2004

AbstractImmobilization of Saccharomyces cerevisiae ATCC 834 within alginate beads enhances microbiological conversion of benzaldehyde to L‐phenylacetyl carbinol (L‐PAC), a precursor employed for synthesis of L‐ephedrine. Yields of 90% L‐PAC on benzaldehyde (initially 0.6% in medium) were obtained with immobilized cells, in contrast to about 10% with free cells which tend to form pellets in the presence of benzaldehyde. The predominant favorable action of immobilization appears to be a reduction in the toxic or inhibitory effects of benzaldehyde. With an initial benzaldehyde concentration of about 0.6% in the medium the optimum cell mass concentration was observed to be about 28 g cell mass (immobilized) per liter of medium.
Effect of regulatory mechanism on hyperbolic reaction network properties
Authors: Majewski R. A. , Domach M. M. 
Published: December 2004

AbstractThe notion that the regulated and flux‐controlling enzyme in a metabolic network need not correspond suggests that the purpose of regulation may not be flux homeostasis under all physiological circumstances. Additionally, the fact that diversity in the function of intact metabolic networks exists suggests that in addition to time constant separation, other kinetic structure/regulatory mechanism patterns exist. In order to compliment and expand prior work on identifying kinetic structure–property relationships in networks, the present work explores in a general way how the control, dynamic, and energetic properties of metabolic networks depend on operating point, kinetic structure, and regulatory mechanism. The basic feature of trade‐offs between properties is illustrated and used as a basis for indicating how particular subsets of structure, regulatory mechanism, and operating point emphasize certain properties that can be associated with a physiological function. Examples of scavenging trace metabolites and amphibolite coordination are proposed. Microstructure logic in terms of turnover number distributions as well as a potential mixed polynomial network analysis approach are also discussed.
Kinetic analysis of the growth of Chlorella vulgaris
Authors: Lehana Mitsunori 
Published: December 2004

AbstractThe energy of the total transmitted light was subtracted from that of the incident light in a culture vessel and the difference was divided by the weight of cells. The value thus obtained was defined as the amount, Ex, of light energy absorbed per unit cell weight per unit time.Batch and continuous cultures of Chlorella vulgaris were carried out at 30°C in the pH range of 6.4–6.7 while restricting illumination. Next the specific growth rate, μ, in the batch culture and the fixed dilution rate, D, in the continuous culture were plotted against Ex. The results showed that the relation between D and Ex can be expressed in a Michaelis–Menten equation, where the maximal specific growth rate is 0.24 h −1 and the saturation constant is 6.58 kcal/g · h.Cell concentration calculated by substituting the apparent concentration, Xe, of incubated cells and the apparent maintenance constant, Me, for this equation agreed with that observed in almost all growth phases. Furthermore, from the change of chlorophyll productivity and the relationship between D and Ex expressed in this equation, it is assumed that Ex involves the light energy directly utilized in photosynthesis in the cells and that which is converted into, e.g., heat. This equation also indicated that a maximum in the growth yield existed. Then the growth yield of 0.029 g/kcal obtained at the incident light of 1.46 or 2.63 cal/cm2 · h was maximum (maximal conversion efficiency of light energy, 15.6%).These results indicate that this method of deriving the equation for the growth rate from this study is a useful procedure for obtaining bioengineering findings.
Countercurrent multistage fluidized bed reactor for immobilized biocatalysts: II. Operation of a laboratory‐scale reactor
Authors: Vos Henk J. , Zomerdijk Max , Groen Dick J. , Luyben Karel Ch. A. M. 
Published: December 2004

AbstractIn Part I of this series,1 we derived a model and made simulations for a multistage fluidized bed reactor (MFBR). It was concluded that the MFBR can be an attractive alternative for a fixed bed reactor when operated with a deactivating biocatalyst. In Part II of this series, the design of a laboratory‐scale MFBR and its evaluation to investigate the practical feasibility of this reactor type, will be described. Experiments with a duration as long as 10 days were carried out successfully using immobilized glucose isomerase as a model reaction system. The results predicted by the model are in good agreement with the measured glucose concentration and biocatalyst activity gradients, indicating perfect mixing of the particles in the reactor compartments.The diameters of the biocatalyst particles used in the experiments showed a large spread, with the largest being 1.7 times the smallest. Therefore, an additional check was carried out, to make sure that the particles were not segregating according to size. Particles withdrawn from the reactor compartments were investigated using an image analyzer. Histograms of particle size distribution do not indicate segregation and it is concluded that the particles used have been mixed completely within the compartments. As a result, transport of biocatalyst is nearly plug flow.
Control of an affinity purification procedure using a thermal biosensor
Authors: Flygare Lilian , Larsson Per‐Olof , Danielsson Bengt 
Published: December 2004

AbstractLactate dehydrogenase (LDH) was recovered from a solution by affinity binding to an N6‐(6‐aminohexyl)‐AMP‐Sepharose gel. An enzyme thermistor unit was employed to continously measure the activity of the unbound LDH. The enzyme activity signal from the enzyme thermistor was used in a PID controller to regulate the addition of AMP‐Sepharose gel to the LDH solution. In another type of experiment, a desktop computer was utilized to control the addition of the adsorbent. Both systems worked satisfactorily, and enabled a rapid and accurate assessment of correct addition of adsorbent.
Enhanced enzymatic activity and stability of trypsin by reductive alkylation in solid phase
Authors: Tsuji Ryohei F. 
Published: December 2004

AbstractAmino groups of trypsin (EC 3.4.21.4) were reductively alkylated in solid phase to obtain a surface‐active and biologically active enzyme in an o/w emulsion system. Trypsin adsorbed on a benzamidine–sepharose column was reductively alkylated with n‐octanal in the presence of sodium borohydride, i.e., trypsin‐C8. Activity of trypsin‐C8 against Nα‐benzoyl‐L‐arginine‐p‐nitroanilide was three times higher than that of native trypsin. Activities of trypsin and trypsin‐C8 against casein were almost the same. After incubating the trypsin solution at 40°C for 1 h, residual activities in the emulsion and solution systems were 64.2 and 57.4%, respectively. On the other hand, residual activities of native trypsin following incubation were 21.8% in the emulsion system and 33.2% in the solution system. Enhancement of trypsin‐C8 stability in the emulsion system may derive from interaction between the hydrophobic areas of trypsin‐C8 molecules and the hydrophobic phase of the emulsion.
Group contributions for estimating standard gibbs energies of formation of biochemical compounds in aqueous solution
Authors: Mavrovouniotis Michael L. 
Published: December 2004

AbstractA method is presented for the estimation of the standard Gibbs energies of formation of biochemical compounds (and hence the Gibbs energies and equilibrium constants of biochemical reactions) from the contributions of groups. The method employs a large set of groups and special corrections. The contributions were estimated via multiple linear regression, using screened and weighted literature data. For most of the data employed, the error is less than 2 kcal/mol. The method provides a useful first approximation to Gibbs energies and equilibrium constants in biochemical systems.
Decrease in iron oxidizing activity of Thiobacillus ferrooxidans adsorbed on activated carbon
Authors: Kai T. , Takahashi T. , Shirakawa Y. , Kawabata Y. 
Published: December 2004

AbstractIt was observed that about 90% of free‐swimming Thiobacillus ferrooxidans in 9 K medium was adsorbed on added activated carbon when the concentration of the cultivated bacteria reached about 4 × 1013 cells m−3. The oxidation of ferrous iron and the leaching of copper ore were carried out in shake flasks and in aerated columns. The rates of oxidation and leaching increased when bacteria adsorbed on activated carbon were used. However, the evaluation of the reaction rates by eliminating the catalytic effect of activated carbon showed that the contribution to the reaction by the adsorbed microorganism was very small.
Continuous cell suspension processing using magnetically stabilized fluidized beds
Authors: Terranova Brenda E. , Burns Mark A. 
Published: December 2004

AbstractThe behavior of a cell suspension in a continuous magnetically stabilized fluidized bed (MSFB) was investigated both experimentally and theoretically. The low, constant pressure drop and fluidity of the solids phase in the MSFB allowed a continuous countercurrent separator to be constructed. The magnetic field eliminated all motion of the solids phase (nickel spheres) and produced a device similar to a packed‐bed depth filter. Yeast cells were used as the suspended solids and the performance of the MSFB filter was assessed as a function of the bed height, solids velocity, cell concentration, and liquid composition. Removal rates could be adjusted by controlling the cell/support interaction and were found to be as high as 99%. A mathematical model was used to aid in understanding this filtration and was found to agree qualitatively with all experimental observations. Comparison of the model with the data suggests that both cell/cell binding and cell shadowing are occurring.
Characterization of a pilot plant airlift tower loop bioreactor: II. Evaluation of global mixing properties of the gas phase during yeast cultivation
Authors: Fröhlich S. , Lotz M. , Korte T. , Lübbert A. , Schügerl K. , Seekamp M. 
Published: December 2004

AbstractSaccharomyces cerevisiae was cultivated in a 4‐m3 pilot plant airlift tower loop reactor with a draft tube in batch and continuous operations and for comparison in a laboratory airlift tower loop reactor of 0.08 m3 volume. The reactors were characterized during and after the cultivation by measuring the distributions of the residence times of the gas phase with pseudostochastic tracer signals and mass spectrometer and by evaluating the mixing in the liquid phase with a pulse‐shaped volatile tracer signal and mass spectrometer as a detector. The mean residence times and the intensities of the axial mixing in the riser and downcomer, the circulation times of the gas phase, and the fraction of the recirculated gas phase were evaluated and compared.
Semicontinuous enzymatic hydrolysis of lignocelluloses
Authors: Ishihara Mitsuro , Uemura Shoko , Hayashi Noriko , Shimizu Kazumasa 
Published: December 2004

AbstractLignocelluloses (steamed hardwood and hardwood kraft pulp) were semicontinuously hydrolyzed on a large scale [2‐2. 5 kg of substrate vs. 20, 000 IU filter paperase (FPase)] using a 10‐L hydrolysis reactor with an ultrafiltration unit for the recovery and reuse of cellulases. The substrate was added to the reactor at appropriate intervals to keep a concentration of approximately 5% (w/v). All of the enzyme was added at the beginning and no further addition was done. The ultrafiltration unit was operated intermittently rather than continuously due to its enough capacity (dilution rate of 2.5 h−1) and making the enzyme durable. The enzyme required to produce one gram of reducing sugar in this reactor was 27.3 FPase IU/g RS for steamed hardwood and 7.4 FPase IU/g RS for hardwood kraft pulp. The sugar composition of hydrolyzate was unaltered virtually from beginning to end of the hydrolysis in spite of the progressive loss of enzyme activities. The analysis of the enzyme composition in the hydrolyzate during hydrolysis revealed that an exo‐β‐D‐glucanase component was adsorbed selectively at the stages of advanced hydrolysis extent.
Control of an Escherichia coli mixed culture via affinity binding
Authors: Roos Joseph W. , Hjortso Martin A. 
Published: December 2004

AbstractA chemostat with population specific recycle was employed to alter the dynamics of a competitive mixed culture of Escherichia coli. Based on differential expression of a functional maltoporin, the two populations were separated by specific adhesion on starch–Sepharose. The slower growing population was the recycled to the reactor. The specific recycle was successful in maintaining the slower growing population at a high level than in comparable reactors without recycle.
An alternate method of calculating the heat of growth of Escherichia coli K‐12 on succinic acid
Authors: Battley Edwin H. 
Published: December 2004

AbstractThe ΔH unit weight of a complex substance such as a biological macromolecule is almost always obtained by means of combustion analysis. In theory, this can also be done by summing the ΔH values for the monomers comprising the macromolecule plus the enthalpic energies involved in their polymerization. The enthalpy of formation of one unit‐carbon formula weight of dried Escherichia coli K‐12 cells was determined by summing the values of the enthalpies of formation of the quantities of monomers in the major classes of macromolecules substances comprising the cellular biomass and the enthalpic energies involved in their polymerizations. To this value was added the enthalpy of formation of the cellular ions in their aqueous standard states, per unit‐carbon formula weight of cellular substance and the enthalpy change with respect to the ionization of the protein amino acid side chains. If it is assumed that the cellular fabric is insoluble and that the ions are soluble, the sum of the enthalpies of formation of all the cellular components should closely approximate the enthalpy of formation of one unit‐carbon formula weight equivalent of living cells. Using this value, a calculation of the enthalpy change accompanying anabolism shows this latter to be effectively zero, indicating that the heat of growth (anabolism plus catabolism) is equal to that calculated for catabolism alone. This conclusion is in accord with those of several investigators who have used manometry or direct calorimetry.
Continuous culture system for production of biopolymer levan using erwinia herbicola
Authors: Keith J. , Wiley B. , Ball D. , Arcidiacono S. , Zorfass D. , Mayer J. , Kaplan D. 
Published: December 2004

AbstractThe optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture yields up to 19% by weight produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and 13C nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low‐angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer.
Linear relations in microbial reaction systems: A general overview of their origin, form, and use
Authors: Noorman H. J. , Heijnen J. J. , Ch. A. M. Luyben K. 
Published: December 2004

AbstractIn microbial reaction systems, there are a number of linear relations among net conversion rates. These can be very useful in the analysis of experimental data. This article provides a general approach for the formation and application of the linear relations. Two type of system descriptions, one considering the biomass as a black box and the other based on metabolic pathways, are encountered. These are defined in a linear vector and matrix algebra framework. A correct a priori description can be obtained by three useful tests: the independency, consistency, and observability tests. The independency are different. The black box approach provides only conservations relations. They are derived from element, electrical charge, energy, and Gibbs energy balances. The metabolic approach provides, in addition to the conservation relations, metabolic and reaction relations. These result from component, energy, and Gibbs energy balances. Thus it is more attractive to use the metabolic description than the black box approach. A number of different types of linear relations given in the literature are reviewed. They are classified according to the different categories that result from the black box or the metabolic system description. Validation of hypotheses related to metabolic pathways can be supported by experimental validation of the linear metabolic relations. However, definite proof from biochemical evidence remains indispensable.
A kinetic analysis of hybridoma growth and metabolism in continuous suspension culture on serum‐free medium
Authors: Hiller G. W. , Aeschlimann A. D. , Clark D. S. , Blanch H. W. 
Published: December 2004

AbstractThe steady‐state metabolic parameters for a murine hybridoma cell line have been determined in continuous suspension culture over a wide range of dilution rates. Long‐term adaption occurred over seven months in culture and resulted in lower glucose consumption rates, reduced lactate production, higher cell viability, and, consequently, growth rates more nearly matching the dilution rate. Antibody production rates decreased over the first two months and then remained stable for at least 75 days. The antibody production rate was not found to be growth associated. Steadystate amino acid uptake rates are presented for a wide range of growth rates.