bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behavior of subcellular marker enzymes during the Hela cell cycle
Authors: Thilly W. G. , Arkin D. I. , Nowak T. S. , Wogan G. N. 
Published: December 2004

AbstractSix enzymes associated with the activities of the nucleus (thymidine kinase), mitochondria (succinate dehydrogenase), lysosomes (acid phosphatase), peroxisomes (catalase), (cytosol lactate dehydrogenase), and the intermembranal mitochondrial space (alkaline DNase) were assayed at 2 hr intervals over the division cycle of repetitively resynchronized HeLa cells. The results indicated a high degree of reproductibility for cells synchronized by the method of perpetual resynchronization and may be of direct use to those interested in subcellular organellogenesis.
Kinetics of a hollow fiber dehydrogenase reactor
Authors: Fink David J. , Rodwell. Victor W. 
Published: December 2004

AbstractA hollow fiber module was used as a reactor for conversion of ethanol to acetaldehyde in the presence of horse liver alcohol dehydrogenase as catalyst. Mass transport rates for NAD+, the overall acetaldehyde generation rate, catalyst effectiveness factors, and the overall order of the reaction with respect to NAD+ concentration were measured. A coupled‐substrate reactor with continuous in situ regeneration of cofactor was also examined. Two substrates of opposite redox state were added simultaneously to the feed stream. NADH and acetaldehyde concentrations were monitored in the effluent stream. The cofactor recycle number, or ratio of moles of product to moles of NADH produced, exceeded 10,000 under certain conditions. While decreasing the NAD+ concentration in the feed stream decreased reactor productivity somewhat, it greatly enhanced the ratio of product formed per mole of NAD+ fed to the reactor. It is suggested that high cofactor costs in dehydrogenase reactors may be overcome with efficient in situ regeneration and secondary recovery and recycling of cofactor from the process stream.
Nitrate and nitrite reduction by liquid membrane‐encapsulated whole cells
Authors: Mohan Raam R. , Li Norman N. 
Published: December 2004

AbstractPurified enzymes and cell‐free homogenates encapsulated by liquid‐surfactant membrane have been shown to retain their catalytic activity (see previously published literature). This paper describes the preparation and properties of liquid‐surfactant membrane‐encapsulated whole cells of Micrococcus denitrificansATCC 21909. Batch and continuous studies with this model system have demonstrated that encapsulated viable cells reduce nitrates and retain their catalytic activity over anextended period of time. In batch operation, the reactivity of the encapsulated whole cells has been investigated under a variety of experimental conditions. The system is capable of reducing NO3− or NO2−. Data obtained indicate that encapsulated live cells have a broad pH and temperature optimum range. The encapsulated cells remain viable and do not “escape” into the external aqueous phase, even after five days of constant stirring with nitrate‐containing simulated wastewater. Pulsed substrate addition experiments have demonstrated that the encapsulated cells also effectively reduce NO2− with no significant reduction in activity, even after 5.5 days of incubation at 30°C. The membrane selectivity for ion transfer has been achieved by incorporating oil‐soluble ion exchangers in the membrane. Because of the protection of the liquid membranes, the catalytic reduction of NO2− by the encapsulated whole cells is not inhibited by 1 × 10−4 M mercuric chloride, which is otherwise extremely toxic to the cells, when present in the external aqueous phase. Continuous reduction of 20 ppm of NO2− by liquid membrane‐encapsulated whole cells has been demonstrated in a constantly stirred reactor over a test period of about one week. In this paper we will discuss the reduction of NO3−and NO2− by the liquid membrane‐encapsulated whole cells of M. denitrificansATCC 21909 mainly in batch runs undera variety of experimental conditions, such as cell and substrate concentrations, product and inhibitor permeation, pH and temperature, effect of oil‐soluble ion exchangers on the substrate diffusion, etc.
Single‐cell protein production by photosynthetic bacteria cultivation in agricultural by‐products
Authors: Shipman R. H. , Kao I. C , Fan L. T. 
Published: December 2004

AbstractThe growth of the nonsulfur photosynthetic bacterium Rhodopseudomonas gelatinosa was investigated as a possible way to produce single‐cell protein from agricultural by‐products. Of the various raw materials examined as potential feedstocks, wheat bran infusion was selected as the substrate for mass culture and continuous cultivation studies. Harvested photosynthetic cells contained approximately 65.0% crude protein and 5.1% nucleic acid (RNA). The amino acid content of harvested photosynthetic proteins was comparable with conventional proteins of plant and animal origin.
The effect of methanol, formaldehyde, and formic acid on growth of Candida boidinii 11 Bh
Authors: Pilát P. , Prokop A. 
Published: December 2004

AbstractThe dependence of the specific growth rate of Candida boidinii 11 Bh on methanol concentration follows Monod‐type kinetics only in a narrow concentration range (0–0.8% v/v), with a saturation constant of about 19 mmol. With a further increase in methanol concentration of up to 3% v/v, the specific growth rate remains constant. Beyond this level, the growth rate gradually drops to zero, reaching the threshold value at 7.8% v/v. The specific growth rate is also strongly dependent on the size of the inoculum. The biomass yield decreases with an increase in the methanol concentration. Formaldehyde and formic acid, oxidative products of methanol, approximately 100 and ten times, respectively, more toxic to growth than the original substrate.
Comparison of batch and semicontinuous cultures for production of protein from mesquite wood by Brevibacterium sp. JM98A
Authors: Fu Tzulin Tom , Thayer D. W. 
Published: December 2004

AbstractThe production of protein by a Brevibacterium sp. JM98A usingmesquite wood as the substrate was compared in batch and semicontinuous cultures. A 14 liter glass fermentor with automatic pH, temperature, and foam control was used for the study. A pH range of 6.6 to 7.2 was optimum for the growth of JM98A. The batch and semicontinuous cultures were compared on the basis of viable cell counts, protein production, CMC‐Ase (β‐1,4‐glucanase) activity, and filter paper cellulase (β‐1,4‐glucan cellobiohydrolyase) activity. Total hexose, cellulose, and reducing sugar consumption were measured. The semicontinuous process yielded 2.97 times as much protein in 72 hr as the batch cultures. Most of the biomass resulted from the utilization of soluble sugars rather than from the degradation of cellulose during the semicontinuous process.
Response of a continuous anaerobic culture to periodic variation of the feeding mash concentration
Authors: Borzani Walter , Gregori Rosana E. , Vairo Marina L. R. 
Published: December 2004

AbstractThe authors studied the influence of periodic variations (one cycle per 24 hr) of the feeding mash concentration of a continuous anaerobic culture of Saccharomyces cerevisiae in sugarcane molasses media at constant dilution rate. It was observed that the average yield coefficients during the transient state were practically equal to the yield coefficient obtained during steady‐state experiments. It was also observed, in each experiment, that the average specific growth rate during the transient state was equal to the dilution rate.
Invertase biosynthesis by Saccharomyces carlsbergensis in batch and continuous cultures
Authors: Toda K. 
Published: December 2004

AbstractThe biosynthesis of invertase by Saccharomyces carlsbergensis LAM 1068 was studied in relation to its glucose effect at both unsteady and steady states of growth. Experimental correlations between the dilution rate and invertase specific activity (E/X) in chemostat, cultures led to an optimum for the enzyme synthesis at a particular intermediate growth rate. The value of E/X increased from 1.1 (U/mg biomass) in batch cultures to 13 (U/mg biomass) in chemostat cultures. A mutant strain A3 showed the highest value for E/X = 25 (U/mg biomass) at high dilution rates where glucose repression was observed with the wild strain.
Aerobic and anaerobic microbial treatment alternatives for shellfish processing wastewaters in continuous culture
Authors: Pohland Frederick G. , Hudson James W. 
Published: December 2004

AbstractShellfish processing wastewaters were characterized and subjected to laboratory‐scale treatability investigations using continuous flow chemostats operated under both aerobic and anaerobic conditions with and without biological solids recycle. System operation and evaluation employed hydraulic retention time as the controlled variable with substrate removal and biomass production as dependent variables. Additional variables specific to anaerobic operation included total and methane gas production rate and volatile acids generation. Application of a kinetic model incorporating the Monod substrate concentration– growth rate function allowed estimation of kinetic coefficients μmax, kd, Y, and Ks.Aerobic treatment of the wastewaters could be adequately described by the kinetic model presented. However, total efficiencies were notably affected by the inherent morphological differences induced by changing hydraulic flows as reflected by poor solids separation at lower and higher retention times. Anaerobic treatment, although not amenable to kinetic description by the model and data presented, exhibited a limited potential for wastewater stabilization in that soluble substrate removals and methane production occurred at all retention times. Difficulties in successfully describing the system kinetically stemmed from an inability to quantify influent solids liquifaction rates. Moreover, evidence of some substrate associated inhibition of methanogenesis was apparent. Solids recycle tended to reduce the inhibitory influences and to increase treatment efficiencies in both the aerobic and anaerobic processes.
The use of α‐galactosidase and invertase in hollow fiber reactors
Authors: Korus Roger A. , Olson Alfred C. 
Published: December 2004

AbstractInvertase and α‐galactosidase have been immobilized in hollow fiber cartridges with no detectable enzyme leakage and used for the hydrolysis of sucrose and raffinose, respectively. For both hollow fiber immobilizes enzymes nearly complete substrate conversion is possible. Enzyme stabilities in polysulfone hollow fibers which have been preconditioned with bovine albumin approach the stabilities of the free enzymes.
Chemically activated collagen for amyloglucosidase attachment. Use in a helicoidal reactor
Authors: Brillouet Jean‐Marc , Coulet Pierre R. , Gautheron Daniele C. 
Published: December 2004

AbstractAmyloglucosidase was covalently bound to collagen sheets by a previously described method. The time of acidic methylation (first step of the collagen activation process) was important to obtain a good enzymatic surfacic activity. Homogeneity of the coupling procedure on the surface of collagen films was shown. Some properties of free enzyme were not affected after grafting: optimum pH and temperature, activation energy, and Km for maltose. Heat stability of the bound enzyme was slightly better; Km for soluble starch increased fivefold. In contrast, the maximal velocity in the presence of soluble starch remained four times that of maltose hydrolysis.Amyloglucosidase collagen membranes were used in a helicoidal reactor to produce glucose from maltose or soluble starch solutions. Tracer studies have shown that the helicoidal reactor behaved as a CSTR. The influence of maltose concentration and flow rate on conversion was studied and confirmed the absence of diffusional limitations for maltose. Recycling of concentrated solutions of maltose and soluble starch indicated strong diffusional restrictions for soluble starch. The catalytic support kept all its activity for 18 days continuous operation at 40°C and 80% after 17 months storage at 4°C.
Characteristics of yeast invertase immobilized on porous cellulose beads
Authors: Dickensheets Paul A. , Chen Li Fu , Tsao George T. 
Published: December 2004

AbstractInvertase from Candida utilis was immobilized on porous cellulose beads by an ionic‐quanidino bond. The immobilized invertase showed optimum activity between pH 4.0 and 5.4, while the free enzyme had a sharp optimum at pH 4.1. Both temperature profiles were fairly similar up to 55°C. However, above this temperature the immobilized enzyme was more stable than the free enzyme. From the temperature data, the activation energies were found to be 7,322 and 4,052 cal/g mol for the free and the immobilized enzyme, respectively.Candida invertase shows characteristics of substrate inhibition. Both the Km and Ki for the free and the immobilized enzymes were determined. The apparent Ki for the immobilized invertase was much higher than the Ki of the free enzyme, suggesting a diffusion effect. Immobilized invertase molecules deep in the pores only see sucrose concentrations much less than the bulk concentrations. Immobilization, thus, offers certain processing advantages in this regard.
Fermentation of glucose by Acetobacter melanogenus
Authors: Stroshane R. M. , Perlman D. 
Published: December 2004

AbstractGrowing cultures of Acetobacter melanogenus ATCC 9937 converted D‐glucose to 2,5‐diketo‐D‐gluconic acid with D‐gluconic acid and 5‐keto‐D‐glucose acid as intermediates. The 2,5‐diketo‐D‐gluconic acid was isolated from the fermented medium by treatment with an anion exchange resin.
Kinetcs and decay of fumarase activity of immobilized Brevibacterium ammoniagenes cells for continuous production of L‐malic acid
Authors: Yamamoto Kozo , Tosa Tetsuya , Yamashita Kiyokazu , Chibata Ichiro 
Published: December 2004

AbstractThe kinetics of the reversible fumarase reaction of immobilized Brevibacterium ammoniagenes cells and the decay behavior of enzyme activity were investigated in a plug flow system. The time course of the reaction in the immobilized cell column was well explained by the time‐conversion equation including the apparent kinetic constants of the immobilized cell enzyme. The decay rate of fumarase activity was faster in the upper sections of the column (inlet side of the substrate solution) compared with the lower sections when 1M sodium fumarate (pH 7.0) was continuously passed through the column at 37°C. It was shown that the decay rate of the fumarase activity in the immobilized cell column depends on the flow rate of the substrate solution. The effect of flow rate on the decay rate of enzyme activity was considered to be related to the rate of contamination of enzyme with poisonous substances derived from the substrate solution or to the rate of leakage of enzyme stabilizers and/or enzyme itself from the immobilized cells.
Comparison of the economics of acid and enzymatic hydrolysis of newsprint
Authors: Grethlein Hans E. 
Published: December 2004

AbstractIn order to compare the process economics of making glucose from cellulose, a plant design is presented using acid hydrolysis which can be compared with a published design using enzyme hydrolysis. A common design basis is used; namely, an input capacity of 885 ton/day newsprint with a common technique of cost estimation. The cost of making glucose is in the range of 1.75 to 2.45 cents/lb, depending on the slurry concentration fed to the reactor for the acid hydrolysis. This cost range is less than the published estimate of 5.2 cents/lb for enzymatic hydrolysis.
An enzyme electrode for measurement of penicillin in fermentation broth: A step toward the application of enzyme electrodes in fermentation control
Authors: Nilsson Hans , Mosbach Klaus , Enfors Sven‐Olof , Molin Nils 
Published: December 2004

AbstractA penicillin sensitive enzyme electrode has been used to analyze the concentration of benzylpenicillin in fermentation broth. The electrode response time was in the region of 2 min and the response to penicillin concentration was linear within the range of 1 to 10mM. The buffering capacity of the medium influenced the sensitivity of the electrode. At low buffer capacity the sensitivity of the enzyme electrode to penicillin was very high, but then the sensitivity to small changes in buffer capacity was relatively large. At high buffer capacity the sensitivity to penicillin was reduced and the electrode became less dependent on changes to buffer capacity. Constant calibration curves were repeatedly obtained with the electrode when used for 2 hr daily in a fermentation medium over a six day period. Three methods devised to calibrate the electrode for use in fermentation media were investigated. Methods one and two, based on the relationship between electrode sensitivity and buffer capacity in phosphate buffer and in sterile media, gave rather high penicillin concentration values. The third method based on an internal standard was the most satisfactory.
Large scale preparation of purified exocellular DD‐carboxypeptidase–transpeptidase of Streptomyces strain R61
Authors: Fossati P. , Saint‐Ghislain M. , Sicard P. J. , Frère M. , Dusart J. , Klein D. , Ghuysen J. M. 
Published: December 2004

AbstractThe exocellular DD‐carboxypeptidase–transpeptidase that Streptomyces R61 excretes during growth has been produced in large fermentation units of 15 m3 total capacity. The yield from 15,000 liter culture filtrate was 1.080 g purified enzyme (92% purity) with a total recovery of 29% and at least a 2000‐fold increased specific activity.
Optimum operating mode for a class of fermentation
Authors: Ohno Hiromu , Nakanishi Eiji , Takamatsu Takeichiro 
Published: December 2004

AbstractThis paper is concerned with optimization of the operating mode of a fermentor. Combining the various modes of operation—batch, semibatch, and continuous—the operating pattern which maximizes the desired metabolic product in a single fermentor is determined by using Kelley's transformation method with Pontryagin's maximum principle. Kelley's transformation method is a device which avoids the singular situation which occurs when the usual procedure of selecting the optimal control function by the maximum principle breaks down. This is the case in the problem considered in this paper. For lysine fermentation, the best operating mode depends on the fermentor capacity and operating time. The results of this study are summarized thus: (i) when the operating time is “long enough,” optimal conditions require that continuous operation follows either semibatch and/or batch operation, and (ii) when the fermentor capacity becomes “large enough,” semibatch operation becomes important.
The rotorfermentor. I. Description of the apparatus, power requirements, and mass transfer characteristics
Authors: Margaritis Argyrios , Wilke Charles R. 
Published: December 2004

AbstractA novel fermentation device, the rotorfermentor, is described and some experimental results are presented on power requirements and oxygen mass transfer characteristics of the rotorfermentor. This fermentation device is designed to achieve high cell concentrations in batch and continuous cultures. Basically, the rotorfermentor consists of a rotating microporous membrane which is enclosed within a stationary fermentor vessel. The metabolic products in the broth are continuously removed by filtration through the rotating microporous membrane while the growing cells can be retained inside the fermentor. This dual function of cell growth and concentration with the simultaneous removal of metabolic products is the essential characteristic of the rotorfermentor.
Effect of immobilized enzyme deactivation in fixed‐ and fluid‐bed reactors
Authors: Sadana Ajit 
Published: December 2004

AbstractA two‐parameter theoretical model is developed to evaluate the effect of immobilized enzyme deactivation on substrate conversion in fixed‐ and fluid‐bed reactors under diffusion‐free conditions. The method describes a simple reaction in which three different immobilized enzyme deactivation forms are considered, and an expression is developed to evaluate the effect of immobilized enzyme deactivation on yield in a consecutive reaction. Comparison of reactor performances for the two reactor types reduces to a comparison of the appropriate dimensionless parameters. The practical implications of the development are illustrated through an example.
Error in oxygen measurements in open systems owing to oxygen consumption in unstirred layer
Authors: Lundsgaard J. S. , Grønlund J. , Degn H. 
Published: December 2004

AbstractWhen a steady‐state oxygen concentration is measured with a membrane‐covered probe in an open system, the oxygen consumption in the unstirred layer gives rise to an error of measurement whose seriousness depends on the kinetics of the oxygen‐consuming process. First‐order oxygen consumption in the sample causes a proportional reduction in the signal so that the calibration in curve remains linear. A zeroth‐order process causes the calibration curve to be offset from the origin, but it remains linear. Oxygen consumption according to the Michaelis–Menten equation causes the calibration curve to become nonlinear with the maximum deviation at the lower end of the scale. The error determines a lower limit for usefulness of membrane‐covered probes. Steady‐state kinetics at oxygen concentrations in the order of KM cannot be determined with a membrane‐covered probe for enzyes with KM for oxygen lower than 0.01μM. In a dense culture of respiring microorganisms, no oxygen will reach the probe when the bulk concentration of oxygen is in the order of KM.
Bacterial growth on organic polymers
Authors: Maxham John V. , Maier Walter J. 
Published: December 2004

AbstractMathematical models are developed describing unsteady‐state bacterial growth on organic polymers that are hydrolyzed by extracellular enzymes secreted by the bacteria to yield low‐molecular‐weight oligomers that may be directly transported across bacterial cytoplasmic membranes and hence metabolized. Two different modes of extracellular enzyme action on the organic polymer are considered. In one case, the enzyme is exoacting yielding a transportable oligomer with each polymer bond hydrolyzed. In the other case, the enzyme is endoacting yielding a series of oligomers upon random cleavage of the polymer bonds with oligomers up to a certain chain length assumed to be transportable. These models are exploited to show under what circumstances the rate of hydrolysis by the extracellular enzyme to yield transportable oligomers influences the bacterial growth rate. It is shown that an initial lag period, an accentuated declining growth phase, and a low overall rate of bacterial growth will be some of the manifestations when the rate of hydrolysis has a strong influence.
Continuous fermentation to produce fungal protein. Effect of growth rate on the biomass yield and chemical composition of Fusarium moniliforme
Authors: Macris B. J. , Kokke R. 
Published: December 2004

AbstractFusarium moniliforme was grown on a carob aqueous extract in a chemostat for fungal protein production. The substrate was adjusted to provide 0.5% carob sugars supplemented with inorganic salts. The dilution rate varied from 0.086 to 0.227 hr−1 under constant conditions of temperature (30°C), pH (4.5), and oxygen saturation (60–80%). A yield of 0.709 g dry mycelium/g consumed carob sugar and a productivity value of 0.687 g dry mycelium/liter hr−1 were obtained at μ = 0.205 hr−1. The maintenance coefficient was 0.077 g carob sugar/g dry mycelium hr−1. While the carbohydrate and purine content of dry mycelium increased at μ values from 0.114 to 0.205 hr−1 both true (Lowry) and crude (N × 6.25) protein contents decreased at the same μ range. Maximum values of 36.3% true and 47.9% crude protein of dry mycelium were obtained at μ = 0.114 hr−1, whereas a minimum purine content of 99.8 μmol/g corresponding to 6.42% nucleic acids was recorded at μ = 0.086 hr−1. It was concluded that a continuous fermentation of carob aqueous extract using F. moniliforme should be operated at growth rates of approximately 0.205 hr−1 in order to maximize protein production.