bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further studies on the mechanism of cell disruption by extreme pressure extrusion
Authors: Brookman James S. G. 
Published: December 2004

AbstractThe use of another air operated extreme pressure hydraulic pump fitted with either a needle valve or a simple microbore tube is described, together with the figures obtained for the soluble protein released from suspensions of commercially obtained baker's yeast (Saccharomyces cerevisiae). The theory of the mechanism is also discussed.
Oxygen transfer to mixed cultures in tower systems
Authors: Hsu Kenneth H. , Erickson Larry E. , Fan Liang‐Tseng 
Published: December 2004

AbstractA modified dynamic method is introduced to determine the oxygen transfer coefficient, KL a, in aerobic fermentation systems which are not mechanically agitated. The dissolved oxygen concentration is measured continuously following a step down or a step up in aeration rate. The response curve is analyzed to obtain the value of KLaExperiments were carried out at several different air flow rates using mixed culture in concurrent tower fermentors with motionless mixers. The effect of sieve trays and Koch motionless mixers on oxygen transfer was investigated using a 3 in. diameter column. The values of KL aobtained at the bottom of each column were found to be higher than those obtained at the top. Comparison of the results showed that the values ofKL a were higher when the Koch mixers were used than when the sieve trays were employed.The oxygen uptake rate by the organisms rX, is also calculated by using the KL a values obtained. They compare favorably withthe experimentally measured values.
Immobilized‐enzyme continuous‐flow reactor incorporating continuous electrochemical regeneration of NAD
Authors: Coughlin Robert W. , Aizawa Masuo , Alexander Bruce F. , Charles Marvin 
Published: December 2004

AbstractElectrochemical regeneration of the cofactor nicotinamide adenine dinucleotide (NAD) from its reduced form (NADH) has been coupled with the alcoholdehydrogenation reaction which consumes NAD and produces NADU using alcohol dehydrogenase bound to alumina. Alcohol (reactant) is added directly to the system while aldehyde (product) leaves the system through an ultrafiltration membrane which prevents loss of the cofactor. This system provides a continuous‐flow process for carrying out a cofactor‐requiring enzymatic reaction with no net loss or consumption of enzyme or cofactor and without the use of reagents for regenerating the cofactor. Although the process shown here is not economically practical, it may be a harbinger of useful and technically feasible chemical reaction systems based on immobilized enzymes requiring cofactors.
Dispersions in hydrocarbon fermentation. A retrospective study
Authors: Bajpai R. K. , Prokop A. , Ramkrishna D. 
Published: December 2004

AbstractA nondimensionalized plot, obtained by normalizing the drop‐size distribution in the hydrocarbon phase using the Sauter mean diameter, shows a tendency towards self‐preservation of the distribution. Changes of distribution in time during the course of fermentation, initial dispersed phase fraction, speed of rotation, and reactor size were taken into account. Using this self‐preserving property, an empirical (single parameter) equation has been proposed for drop‐size distribution. Data, available from the literature, are presented for non‐biological and biological systems (gas‐oil, n‐hexadecane, and n‐hexadecane dissolved in dewaxed gas oil as dispersed phases). The parameter, Sauter mean diameter, has been correlated with the operating conditions, and a critical review presented. Cell density was found to have significant effect on Sauter mean diameter. This effect has also been empirically explained. The possibilities of using generalized distribution in predicting the performance of fermenters is outlined.
Design of a large‐scale mammalian cell, suspension culture facility
Authors: Lynn J. Daniel , Acton Ronald T. 
Published: December 2004

AbstractThe design of a suspension culture facility capable of producing approximately 1012 cells per week has been developed on a small‐scale system which has evolved from various architectural, engineering, biological, and biohazard considerations. The smaller system is composed of spinner flasks (50 ml to 8 liters) modified for semicontinuous culture conditions, metal reservoirs, a continuous flow centrifuge, and supportive equipment. The large system which is under construction is composed of metallic vessels of up to 500 liter working volume with hard plumbing, monitors, controllers, recorders, continuous flow centrifuge and other ancillary equipment. This system begins with medium preparation and ends with harvesting of cells and disposition of supernatant. The design of this turn‐key operation was developed over a two and one‐half year period through the cooperation of private industry, the federal government, and the academic community.
Rapid measurement of monod half‐velocity coefficients for bacterial kinetics
Authors: Williamson Kenneth J. , McCarty Perry L. 
Published: December 2004

AbstractThe common methods for measuring Monod half‐velocity coefficients are reviewed. All methods have serious disadvantages for obtaining rapid and accurate measurements whether batch‐fed or continuous‐fed systems are used. An “infinite dilution” technique is described that overcomes these difficulties. Data obtained by this method for autotrophic oxidation of NO2− and NH4+gave 20°C, pH 7.0, K3 values of 0.07 mg NO2−‐N/liter and 0.50 mg NH4±N/liter, respectively.
The transient response to pH and temperature shock loading of fermentation systems
Authors: Gaudy A. F. 
Published: December 2004

AbstractRecent findings in the author's laboratories relative to the determination of the mode of response of continuously cultured heterogeneous populations to step changes in pH and in temperature are reviewed and discussed in light of possible effects of specific growth rate, μ, on the severity of substrate leakage in the effluent during the transient phase.
Thermophilic Anaerobic Digestion of Solid Waste for Fuel Gas Production
Authors: Cooney Charles L. , Wise Donald L. 
Published: December 2004

AbstractAnaerobic digestion offers a potential means of converting organic solid waste into fuel gas and thereby provide a supplemental and readily utilizable source of energy. We are particularly interested in the use of thermophilic digestion over a mesophilic operation for it can achieve higher rates of digestion, greater conversion of waste organics to gas, faster solid–liquid separation, and minimization of bacterial and viral pathogen accumulation. Our results comparing mesophilic (37°C) and thermophilic (65°C) anaerobic digestion of domestic solid waste confirm the increased rate and conversion of waste to methane. In addition, utilizing radioactive labeling of glucose and acetic acid, we have measured the volumetric rates of volatile acid production and disappearance under both mesophilic and thermophilic conditions.
Wine fermentations using membrane processed hydrolyzed whey
Authors: Roland J. F. , Alm W. L. 
Published: December 2004

AbstractA process for the utilization of modified whey syrups in wine alcohol fermentations is described. Palatable wines containing 10–12.5% alcohol were produced when various strains of S. cerevisiae var. ellipsoideus were fermented with hydrolyzed whey permeate syrups and grape juice concentrates. Experimental control of final alcohol and residual sugar levels in the wines by various chaptalization techniques is discussed. The possibility of utilizing this process in areas where both whey and grapes are abundant is mentioned.
Stimulation by organic solvents and detergents of conversion of L‐sorbose to L‐sorbosone by Gluconobacter melanogenus IFO 3293
Authors: Martin C. K. A. , Perlman D. 
Published: December 2004

AbstractTreatment of Gluconobacter melanogenus IFO 3293 cells with benzene, carbon tetrachloride, cyclohexane, deoxycholate, toluene, or xylene stimulated their conversion of L‐sorbose to L‐sorbosone two‐ to threefold. The degree of stimulation depended upon the length of exposure time to the agent and the age of the G. melanogenus cells. A rapid decrease in viability of the cells and degradation of cell RNA was noted after treatment with the effective agents. The G. melanogenus cells were unable to absorb L‐sorbose actively after toluene treatment.
Enzyme immobilized in a packed‐bed reactor: Kinetic parameters and mass transfer effects
Authors: Marrazzo W. N. , Merson R. L. , McCoy B. J. 
Published: December 2004

AbstractTo describe axial dispersion, particle film mass transfer, intraparticle diffusion, and the chemical reaction of the substrate for enzymes immobilized in porous particles in packed columns, we have developed mathematical models for first‐ and zero‐order limits of Michaelis‐Menten kinetics. Steady‐state solutions were derived for both long and short column boundary conditions and for plug flow. Theory was compared to experiments of hydrolysis of sucrose catalyzed by invertase bound to porous glass particles. Steady‐state conversions were measured for a range of flow rates. Pulse response experiments with inert packing were used to determine values of bed void fraction and particle porosity.
Extended Monod equation for batch cultures with multiple exponential phases
Authors: Tsao George T. , Hanson Thor P. 
Published: December 2004

AbstractThe batch growth curves of Laclobacillus delbreuckii exhibit several exponential phases. From the results of a series of shaker flask experiments, the position of the slope changes in the growth curve and the overall bacterial yield is affected by the initial amount of yeast extract in the medium. It is postulated that this behavior is due to several growth enhancing substances that are initially in the yeast extract and are consumed by the bacteria during the course of the fermentation. Using a Monod‐type expression to represent the effect of growth enhancing components in a proposed growth rate expression, a mathematical model of the system is set up and solved on the analog computer.
Reversal of enzymatic hydrolysis: Rate and extent of ester synthesis as catalyzed by chymotrypsin and subtilisin Carlsberg at low water concentrations
Authors: Ingalls Robert G. , Squires Robert G. , Butler Larry G. 
Published: December 2004

AbstractImmobilized chymotrypsin catalyzes esterification of N‐acetyltyrosine in a medium containing high concentrations of alcohols. The hydrophilic support and inclusion of glycerol protect the enzyme activity and allow catalysis to proceed in the presence of only 10% (v/v) water. The same equilibrium concentration of ester is obtained whether reaction proceeds from ester or from free acid. Hates of ester synthesis and hydrolysis are similar when measured under the same conditions, but are at least one order of magnitude slower than optimal rates of hydrolysis. Subtilisin Carlsberg in the free, unmodified form catalyzes ester synthesis at even lower water concentrations; optimal rates are obtained at 5–15% H2O.Hydrolytic enzymes can thus be utilized as catalysts of synthesis reactions in nonaqueous solvents where synthesis is thermodynamically favored over hydrolysis; in some cases this may provide economic and/or energetic advantages over conventional techniques.
Thermophilic microbiological treatment of high strength wastewaters with simultaneous recovery of single cell protein
Authors: Surucu G. A. , Engelbrecht R. S. , Chian E. S. K. 
Published: December 2004

AbstractSimultaneous removal of organic materials and recovery of protein in the form of bacterial cells from a simulated high strength biodegradable wastewater was studied using thermophilic aerobic microorganisms. A naturally occurring mixed culture of thermophilic microorganisms was obtained from soil, wastewater, hay, silage, etc. A chemically defined medium containing glucose along with other essential nutrients was employed as the feed. The kinetic behavior of the culture was studied in a continuous culture at an optimum temperature of 58°C. Studies were also performed on the effects of solids retention time (SRT) on the observed cell yield and the protein and ash content of the harvested biomass. An economic analysis of the process or single cell protein recovery was given.
The yields of extracted protein and of residual fiber from potato haulm taken as a by‐product
Authors: Carruthers I. B. , Pirie N. W. 
Published: December 2004

AbstractIn July the yield of protein extractable from potato haulm could be 600 kg/ha and the beginning of September it is 200 kg/ha. The yield of fiber containing 1 to 2% N is less affected by maturity. The annual waste of extractable protein, suitable for feeding nonruminants, is about 60,000 tons. The contribution that some small changes in conventional potato husbandry might make to minimizing this waste is discussed.
Investigation of the unit operations involved in the continuous flow isolation of β‐galactosidase from Escherichia coli
Authors: Higgins J. J. , Lewis D. J. , Daly W. H. , Mosqueira F. G. , Dunnill P. , Lilly M. D. 
Published: December 2004

AbstractA 1000 liter fermentor has been used to produce a continuous feed of Escherichia coli containing a high level of β‐galactosidase. We have investigated the individual unit operations for the isolation of the enzyme: cell disruption, nucleic acid removal, protein precipitation, and solid–liquid separation after each stage. Using the information obtained we have been able to operate a semicontinuous process which when fully continuous would yield 100 g protein/hr, comprising 23% β‐galactosidase.
Rate of catalytic oxidation and decomposition of NADH by graphite in aqueous solutions
Authors: Wallace Thomas C. , Coughlin Robert W. 
Published: December 2004

AbstractGraphites of different manufacture and origin exert positive but different accelerations on the rate of oxidation of NADH to NAD+ in aqueous solution; different proportions of the oxidized form of NAD retain enzymatic activity depending on the nature of the graphite. Oxidative pretreatment of the graphite surfaces increases the rates of NADH oxidation, but subsequent silanization of the surfaces to attach alkylamine groups causes the rates to decrease. The experimental results suggest the presence of at least two types of sites on graphite surfaces: One very reactive site which produces a high percentage of an enzymatically inactive reaction product of NADH and is itself deactivated during the course of reaction, and another type of site which promotes the oxidation of NADH to enzymatically active NAD+ in high yields.
Distribution of dispersed oil phase in hydrocarbon fermentations
Authors: Ho Chester S. , Erickson Larry E. 
Published: December 2004

AbstractRecent experimental results show that the spreading coefficient frequently becomes positive when Candida lipolytica is cultivated on n‐hexadecane. The effects of oil spreading at the surface of air bubbles in an airlift fermentor are examined using a mathematical model. The distribution of the oil phase with position and among the phases is determined using computer simulation. The simulation results qualitatively explain some of the experimental observations which have been previously reported.
Oil drop size and gas hold‐up in an oil–water airlift system with motionless mixers
Authors: Gutierrez J. R. , Erickson L. E. 
Published: December 2004

AbstractThe degree of emulsification, measured as surface area of oil generated, was studied. The effect of interfacial tension, volume fraction of oil, and power per unit volume on the Sauter mean diameter of the oil drops was determined in an airlift system with motionless mixers. A mathematical expression to predict the Sauter mean diameter was developed using regression techniques. From this equation another equation, which will predict the surface area of oil in terms of the same variables, was derived. The effects of water air surface tension and power per unit volume on the gas hold‐up were obtained using similar techniques. The results show that the interfacial tension and the surface tension are important variables when hydrocarbon fermentations are carried out in airlift systems.
Mixing, mass transfer, and scale‐up of polysaccharide fermentations
Authors: Margaritis Argyrios , Zajic James E. 
Published: December 2004

AbstractMicrobial polysaccharides are rapidly emerging as a new and important source of polymeric materials. These biopolymers have novel and unique properties and already have found a wide range of applications in the food, pharmaceutical, and other industries. In view of the impending importance of polysaccharides as an industrial commodity, there is renewed interest in the area of product and process development. This paper summarizes the state‐of‐the art in polysaccharide fermentations. An attempt is being made to review the following areas: rheological characteristics of polysaccharide solutions, mixing and power requirements of polysaccharides and other highly viscous non‐Newtonian systems, oxygen mass transfer, and scale‐up problems encountered in polysaccharide fermentations.
Alkali treatment and fermentation of straw for animal feed
Authors: Han Y. W. , Yu P. L. , Smith S. K. 
Published: December 2004

AbstractThe feed value of annual ryegrass straw was improved by treatment with various concentrations of NaOH or NH3 followed by fermentation of the treated straw with a mixed culture of Cellulomonas sp. and Alcaligenes faecalis. Laboratory feeding trials with voles showed that NaOH or NH3 treatment considerably increased the feed efficiency of straw, but apparently gave a poorly palatable product. Fermentation tended to decrease the in vitro rumen digestibility (IVRD) of alkali‐treated straw. The fermentations were carried out aerobically on a semisolid straw matrix having 11–86% moisture. Treatment by both NaOH and NH3 increased the IVRD of straw. NH3 also increased the nitrogen content in straw. The optimum condition for alkaline treatment of the straw was 4–6% NaOH for 1 hr or with 3% NH3 for four weeks at room temperature. A minimum of 63% moisture was needed for significant fermentation of the straw. The combined effects of NaOH treatment and fermentation more than doubled crude protein, doubled crude fat, and increased IVRD by 75%. The NH3 plus fermentation treatment tripled crude protein, doubled crude fat, and increased IVRD by 60%. Acetic acid was the main volatile fatty acid in the fermented straw.
Solubilization of cheese whey protein by trypsin and a process to recover the active enzyme from the digest
Authors: Monti J. C. , Jost R. 
Published: December 2004

AbstractPorcine trypsin (EC 3.4.4.4) converted, within approximately 2 hr at 50°C, its 1000‐fold weight of water‐insoluble, heat‐denaturated cheese whey protein into a water‐soluble product. In the course of this digestion, the enzyme increased the α‐amino nitrogen of the protein by a factor of >20, from 0.40 to 9.40%. After digesting the water‐insoluble whey protein, fully active trypsin could be recovered from the soluble digest with the aid of a cellulose‐based affinity adsorbent. The enzyme which was eluted from a column of p‐aminobenzamidine, bound to succinylated aminododecylcellulose, was fully active and showed essentially unchanged kinetic properties with a synthetic substrate, L‐benzoyl‐arginine p‐nitroanilide. It was possible to perform, with the same amount of trypsin, three subsequent and equally effective solubilizations of whey protein, followed by a fourth digestion which still yielded a soluble product, but was considerably slower and incomplete. During each digestion, an estimated 30% of the trypsin was lost. The was not due to a decreased efficiency of the affinity adsorbent, as its trypsin‐binding capacity was essentially unaffected after over 10 cycles of use.
Adsorption of cellulose by Trichoderma viride
Authors: Binder A. , Ghose T. K. 
Published: December 2004

AbstractAdsorption of cellulase by Trichoderma viride QM 9414 has been studied with resting and growing cells and equations have been derived to describe the process quantitatively. It has been observed that the adsorption is a purely physical process being dependent only on cell and cellulose concentrations. It has also been demonstrated that adsorption isrequired for the induction of cellulases; some discussions are devoted to this point.
Toxic effects of fatty acids on yeast cells: Possible mechanisms of action
Authors: Huňková Z. , Fencl A. 
Published: December 2004

AbstractAs shown in a previous paper, threshold concentrations of lower and intermediate fatty acids inhibit the uptake of inorganic phosphate, growth, and cell division in yeast cells, This paper demonstrates that, apart from these effects, the acids cause an increase in the respiration quotient (RQ), inhibition of CO2 fixation, production of ethanol at the expense of anabolic processes, and inhibition of active amino acid transport in the yeast Candida utilis. On the other hand, the threshold concentrations have no effect on intracellular pH. The inhibition of the inorganic phosphate uptake cannot be the sole primary mode of action of fatty acids since the omission of inorganic phosphate in the incubation medium brings about an inhibition of anabolic processes that is lower than that brought about by fatty acids at concentrations still permitting some phosphate uptake, Although 2,4‐dinitrophenol and caproic acid at low concentrations cause an analogous decrease in biomass yield, their combination does not bring about any marked increase in the effect. Considering the physicochemical properties of fatty acids and their preferential action on energy‐requiring processes, one of the key sitesof action can be assumed to be the mitochondrial membrane. Fatty acids might inhibit the transport of anions, especially phosphate, across the membrane, and disturb the membrane potential by affecting the transport protons. The physicochemical properties of fatty acids may also give rise to their binding to other intracellular membranes and to a subsequent interference with the function of the corresponding organelles.
Potentiometric determination of coenzyme‐dependent oxidoreductase enzymes with recycling of the coenzyme
Authors: Wallace Thomas C. , Coughlin Robert W. 
Published: December 2004

AbstractBy enzymatically establishing a rapid (essentially equilibrium) coupling of a redox coenzyme such as NAD with the components of the ferrocyanide–ferricyanide half‐cell (e.g., using excess diaphorase) the half‐cell potential can be used to monitor another enzymatic reaction involving the same coenzyme. This approach provides a general, rapid potentiometric method of assaying coenzyme‐dependent oxidoreductase enzymes. We show that these assay systems can be designed for multiple turnover of coenzyme (in our case NAD) during a single assay thereby amplifying the rate of electromotive force (emf) change with a concomitant increase in sensitivity of enzyme assay. This allows the use of small concentrations of coenzyme and extension of the range of enzyme concentrations that may be assayed.
Some factors affecting the stability of glucoamylase immobilized on hornblende and on other inorganic supports
Authors: Flynn A. , Johnson D. B. 
Published: December 2004

AbstractGlucoamylase from four different companies was studied: three had similar stability (half‐life at 50°C about 140 hr); the fourth was less stable (half‐life at 50°C about 20 hr). The immobilized enzymes were all less stable than their soluble counterparts: immobilized enzyme stability depended on the soluble enzyme used, the support, and method of immobilization. Thus enzyme bound to Enzacryl‐TIO was less stable than enzyme bound to hornblende (metal‐link method); this, in turn, was less stable than enzyme bound to hornblende by a silane–glutaraldehyde process. Bound enzyme stability was also improved by the presence of substrate or product (starch maltose or glucose). After 110 hr at 50°C in the presence of maltose (10% (w/v)) one preparation (a more stable soluble enzyme boul1d to hornblende by a silane–glutaraldehyde process) retained over 95% of its activity: activity loss was too low to permit the estimation of a half‐life.