bluuebunny/crossref_metadata_2025_split huggingface dataset:
An assessment of the role of physiological adaptation in the transient response of bacterial cultures
Authors: Daigger Glen T. , Grady C. P. Leslie 
Published: December 2004

AbstractThe RNA‐limiting theory of transient response states that the primary physiological adaptation which occurs when microbial cultures are grown at specific rates less than their maximum is a decrease in the cellular level of RNA. It predicts that, as a result of this decrease, the response of the culture to a shift‐up in growth rate will be limited by its RNA level. In order to test the RNA‐limiting theory and to investigate the role physiological adaptation in transient response, experiments were performed in which steady‐state chemostat cultures of Pseudomonasputida grown at various specific rates were transferred to batch reactors containing sufficient carbon source (L‐lysine) and nutrients to remove all external growth restrictions. Samples were collected during the subsequent transient period for determination of the macromolecular composition and the maximum instantaneous oxygen uptake rate. The results indicated that, while decreases in the RNA level did significantly affect the nature of the transient response, other unidentified components varied with the steady‐state specific growth rate at which the culture had been grown prior to the shift‐up and that the levels of those components affected the nature of the subsequent transient response. This implies that the RNA‐limiting theory is inadequate for describing the transient responses of cultures grown over a wide range of specific growth rates.
Technology advances for continuous compression milling pretreatment of lignocellulosics for enzymatic hydrolysis
Authors: Tassinari Thomas H. , Macy Charles F. , Spano Leo A. 
Published: December 2004

AbstractThe feasibility of a continuous compression milling pretreatment process for the enzymatic hydrolysis of lignocellulosics has been demonstrated. Pretreatment efficiency was improved significantly by adjustment of feedstock moisture content prior to milling and/or increasing the roll pressure on the feedstock. Optimum moisture contents for newspaper (24%). corn stover (17%), popular (12–20%) were determined. Sugar Yields of 48% were obtained from air‐dried newspaper after six passes through even‐pressure rolls and the specific energy input was 0.21kW h/lb. The Effect of roll speed on enzymatic hydrolysis improvement was constant over a roll speed range of from 30–110 ft/min (65 rpm). Enzymatic hydrolysis results from commercial‐scale pretreatment of moist newspaper processed at 6 tons/h/ correlated well with laboratory mill data while energy consumption was 26% less.
Utilization of the “complex method” to optimize a fermentation process
Authors: Saguy Israel 
Published: December 2004

AbstractThe complex method has been applied to maximize the profit of a fermentation process. The optimization method is based on sequential search technique and may be implemented in most process which can be stimulated. Utilizing the derived optimal value of the controllable variables (the concentration of glucose, soybean meal, phosphate, and salt; agitation and aeration rates; inoculum size; and fermentation duration) resulted in a substantial profit increase.
Ethanol production by extractive fermentation
Authors: Minier M. , Goma G. 
Published: December 2004

AbstractThe ideal method to produce a terminal metabolite inhibitor of cell growth and production is to remove and recover it from the fermenting broth as it formed. Extractive fermentation is achieved in the case of ethanol production by coupling both fermentation and liquid‐liquid extraction, The solvent of extraction is 1‐dodecanol (or a mixture 1‐dedecanol, 1‐tetradecanol); study of the inhibitory effect of primary aliphatic alcohols of different chain lengths shows that no growth is observed in the presence of alcohols which have between 2 and 12 carbons. This effect is suppressed when the carbon number is 12 or higher. A new reactor has been used–1 pulsed packed column. Pulsation is performed pneumatically. Porous material used as a package adsorbs the cells. The fermentation broth is pulsed in order to (1) increase the interfacial area between the aqueous phase and the dodecanol, (2) decrease gas holdup. Alcoholic fermentation, performed at 35°C on glucose syrup, permits the total utilization of glucose solution of 409 g/L with a yeast which cannot–in classical process– completely use solutions with 200 g/L of glucose. The feasibility of a new method of fermentation coupling both liquid‐liquid extraction and fermentation is demonstrated. Extension of this method is possible to any microbial production inhibited by its metabolite excretion.
Immobilization of Nitrosomonas europaea cells with polyelectrolyte complex
Authors: Kokufuta Etsuo , Matsumoto Wataru , Nakamura Isei 
Published: December 2004

AbstractCell immobilization with polyelectrolyte complex prepared from strongly polyacidic and polybasic ions was investigated for cells from Nitrosomonas europaea (ATCC 25978). Trimethylammonium glycol chitosan (TGCI) and potassium poly(vinyl‐alcohol) sulfate (KPVS) were used. The immobilization was carried out by directly mixing both polymer solutions with the culture broth: An excess of TGCI was first added to the culture broth to aggregate the cells, and then KPVS was added to form the complex with the excess TGCI and to entrap the aggregates with the resulting complex. From physiocochemical studies on the cell aggregation, the mechanism can be interpreted in terms of the adsorption of polyion caused by the salt linkages of the ionizable groups on the cell surface. The result of an electron microscopic observation showed that the cells are situated in the pores and on the surface of the complex support. When the immobilized cells were incubated in a medium buffered by phosphate and containing ammonium sulfate, a considerable amount of nitrite was formed; this was shown to be caused by the entrapped cells and also those cells released from the support and grown in the medium. The ammonia‐oxidizing activity was retained even after a total of 200 h of incubation in a batch reactor. No deformation of the complex support was observed.
The effect of methylacrylate on the activity of glucomylase immobilized on granular polyacrylonitrile
Authors: Handa Takashi , Hirose Akira , Yoshida Shoji , Tsuchiya Haruo 
Published: December 2004

AbstractGlucoamylase was immobilized on granular polyacrylonitrile (PAN) and the optimum condition in its immobilization reaction was determined. The effect of the ratio of the imidoester and methylester to the total cyanogen on the activity of the immobilized enzyme was studied. The activity of the immobilized enzyme increased in proportion to the molar number of imidoester and decreased with that of methylester. The Km and Vm values of immobilized glucoamylase which were prepared at various conditions of immobilization were determined. There were opposite trends in KmS between glucoamylase immobilized on imidoester‐rich support and immobilized on methylester in the support, evidenced as functions of temperature. This suggests that opposite charges in the support, produced by heat deformation of PAN by hydrolysis of methylester, were an influence on the apparent Km of immobilized glucoamylase, besides the diffusional limitation.
Large‐scale mammalian cell culture: Design and use of an economical batch suspension system
Authors: Tolbert William R. , Schoenfeld Richard A. , Lewis Charles , Feder Joseph 
Published: December 2004

AbstractLarge‐scale mammalian cell culture in the absence of antibiotics requires stringent conditions of sterility for all vessels, procedure, and systems used. Application of existing fermentation technology suffers from the differences between mammalian and bacterial cultures. Relatively simple and inexpensive 100‐L vessels have been designed specifically for medium storage and antibiotic‐free mammalian cell culture. These vessels are portable and sterilized in a 2 × 3 × 5 ft conventional or VACUMATIC autoclave. They consist of 30‐gal 316 stainless‐steel sanitary process drums whose heads have been modified to meet the rapid pressure changes that occur during autoclaving. The vessels incorporate systems for aseptic introduction and removal of both liquids and gases required for inoculation, growth, and harvesting of cell suspensions. A two‐disk vibromixer is used for agitation with inoculation at a laminar flow hood and incubation in a warm room. These vessels have been used for culture of one rat and eight human tumor lines for over 2 × 105 L of suspension.
Stabilization of waste‐activated sludge through the anoxic‐aerobic digestion process
Authors: Hashimoto Susumu , Fujita Masanori , Terai Kazuhiro 
Published: December 2004

AbstractDuring the aerobic digestion process, the nitrogen which had been embedded in the activated sludge is solubilized to form ammoniacal and nitric nitrogen which are in turn transferred to the liquor and cause the increase of nitrogen loading in the sewage treatment plant. In this study, the anoxic‐aerobic sludge digestion system which is a modified form of the conventional aerobic sludge digestion is made up of aerobic and anoxic tanks and are designed to remove both the volatile suspended solids and the total nitrogen (TN) simultaneously. The removal efficiencies of both VSS and TN were investigated by feeding waste‐activated sludge continuously and semicontinuously. The maximum percent reduction of both VSS and TN was achieved at a Qr/Qs ratio of 2 in the continuous process. The semicontinuous process was used to improve the nitrogen removal efficiency further. In the semicontinuous process, the VSS reduction efficiency as well as the nitrogen removal efficiency increased remarkably under a constant Qr/Qs ratio of 2. This process also achieved a VSS reduction efficiency higher than the aerobic digestion process (control). It was suggested that the additional anoxic tank enhanced the sludge digestion. Furthermore, the anoxic‐aerobic digestion system can be applied to other treatment media like the primary sludge, industrial sludge, animal manure, etc.
Solubility of plasma proteins in the presence of polyethylene glycol
Authors: Haskó Ferenc , Vaszileva Roza , Halász László 
Published: December 2004

AbstractThe solubility of plasma proteins was studied at various pH as a function of polyethylene glycol concentration. Computer analysis of precipitation curves permitted equations to be derived. The equations describe the relationship between protein solubility and polyethylene glycol concentration. The analysis of the equations furnished further data for the validity of the displacement theory.
A study of acetic acid production by immobilized Acetobacter cells: Product inhibition effects
Authors: Ghommidh C. , Navarro J. M. , Messing R. A. 
Published: December 2004

AbstractAcetobacter living cells were immobilized by adsorption onto a ceramic support. The effects of acetic acid inhibition have been studied in a fixed‐bed pulsed‐flow reactor. Provided that sufficient oxygen was available, the concentration of acetic acid was found to be independent of the flow rate. Damped oscillations of acetic acid concentration were observed after step changes in dilution rate. The theoretical model developed from steady‐state data was successful in predicting the experimental dynamic behavior of the reactor.
Adsorption of cellulase on cellulose: Effect of physicochemical properties of cellulose on adsorption and rate of hydrolysis
Authors: Lee Sun Bok , Shin H. S. , Ryu Dewey D. Y. , Mandels M. 
Published: December 2004

AbstractIn the cellulase–cellulose reaction system, the adsorption of cellulase on the solid cellulose substrate was found to be one of the important parameters that govern the enzymatic hydrolysis rate of cellulose. The adsorption of cellulase usually parallels the rate of hydrolysis of cellulose. The affinity for cellulase varies depending on the structural properties of cellulose. Adsorption parameters such as the half‐saturation constant, the maximum adsorption constant, and the distribution coefficient for both the cellulase and cellulsoe have been experimentally determined for several substrates. These adsorption parameters vary with the source of cellulose and the pretreatment methods and are correlated with the crystallinity and the specific surface area of cellulose substrates. The changing pattern of adsorption profile of cellulase during the hydrolysis reaction has also been elucidated. For practical utilization of cellulosic materials, the cellulose structural properties and their effects on cellulase adsorption, and the rate of hydrolysis must be taken into consideration.
Immobilized enzymes: Electrokinetic effects on reaction rates under external diffusion
Authors: Kalthod Dilip G. , Uckenstein Eli 
Published: December 2004

AbstractThe rates of reactions catalyzed by enzymes immobilized on a nonporous solid surface have been computed employing a Nernst film model. The Nernst‐Planck equations for the transport of the charged substrate and product species in the film and the Poisson equation for the distribution of electrical potential are solved numerically with the appropriate boundary conditions. The electrical charge at the surface is assumed to arise from the dissociation equilibria of the acidic and basic surface groups of the enzyme. The pH at the surface affects both the surface charge as well as the intrinsic kinetics of the enzyme‐catalyzed reaction. Factors which determine the pH at the surface include the pH in the bulk solution and the release of H+ ions in the enzyme‐catalyzed reaction. The latter causes a lowering of pH at the surface, causing the reaction rate to differ from that computed assuming an equilibrium distribution of electrical potential. Another kind of nonequilibrium contribution is caused by unequal charges or diffusivities of the substrate and products, which results in a diffusion potential being set up. Two moduli are introduced to evaluate the significance of the reaction‐generated lowering of pH and the diffusion potential effect. The effect of changing various parameters, e.g., reaction rate constant, substrate concentration, enzyme concentration, pH, etc., on the overall reaction rate are studied.
Effect of mass transfer in a recirculation batch reactor system for immobilized penicillin amidase
Authors: Park Jong M. , Choi Cha Y. , Seong Baik L. , Han Moon H. 
Published: December 2004

AbstractThe effect of external mass transfer resistance on the overall reaction rate of the immobilized whole cell penicillin amidase of E. coli in a recirculation batch reactor was investigated. The internal diffusional resistance was found negligible as indicated by the value of effectiveness factor, 0.95. The local environmental change in a column due to the pH drop was successfully overcome by employing buffer solution. The reaction rate was measured by pH‐stat method and was found to follow the simple Michaelis‐Menten law at the initial stage of the reaction. The values of the net reaction rate experimentally determined were used to calculate the substrate concentration at the external surface of the catalyst pellet and then to calculate the mass transfer coefficient, kL, at various flow rates and substrate concentrations. The correlation proposed by Chilton and Colburn represented adequately the experimental data. The linear change of log jD at low log NRe with negative slope was ascribed to the fact that the external mass transfer approached the state of pure diffusion in the limit of zero superficial velocity.
Pentosan hydrolysis in a concentrated slurry system
Authors: Horwath J. A. , Mutharasan R. , Grossmann E. D. 
Published: December 2004

AbstractPentosan hydrolysis at low aqueous liquid‐to‐biomass ratios (2.5–15 mL/g) with sulfuric acid as the catalyst is studied in the temperature range of 125–155°C. To facilitate heat transfer and mixing a second insoluble oil is added to the reaction mixture. It is found that even at high slurry concentrations, the reaction is the rate‐controlling step. In addition, such systems give higher pentosan yields compared with dilute slurry systems. This is explained using the concept of acid loading which is defined as the acid present per unit mass of biomass.
Adsorption of radium‐226 by biological origin absorbents
Authors: Tsezos M. , Keller D. M. 
Published: December 2004

AbstractSelected samples of waste microbial biomass used in industrial fermentation processes and wastewater biological treatment plants have been studied for their radium biosorption ability from aqueous solutions. Equilibrium biosorption isotherms have been used to quantify the radium uptake capacity of the various types of biomass which were also compared to two types of activated carbon. Solution pH affected the observed uptake significantly. In general, the biomass types that showed appreciable sorption capacity exhibited maximum uptake between pH 7 and 10. The uptake was reduced considerably at pH 4 and little or no uptake was observed at pH 2. Radium biosorptive uptake capacities of the order of 4.5 × 104 nCi/g, at pH 7 and at an equilibrium radium concentration of 1000 pCi/L, were determined for a mixed culture, while the biomass of Penicillium chrysogenum adsorbed 5 × 104 nCi/g radium under the same conditions. The highest uptake value for a sample of F‐400 granular activated carbon was 3600 nCi/g at pH 7 and 1000 pCi/L radium concentration. The biosorptive radium uptake of microbial biomass is compared to literature values for other types of adsorbents. The most effective biomass types studied exhibited radium removals in excess of 99% of the radium in solution.
Growth monitoring and control through computer‐aided on‐line mass balancing in a fed‐batch penicillin fermentation
Authors: Mou Duen‐Gang , Cooney Charles L. 
Published: December 2004

AbstractA computer‐aided methodology is developed for on‐line monitoring and control of cell growth in fed‐batch penicillin fermentation using a semidefined medium containing low corn steep liquor concentration (5.7 g/L). Cell growth is monitored and controlled with the use of experimental correlation and carbon‐balancing equatiions on a real‐time basis throughout the fermentation. Through a combination of feed‐forward and feedback control of sugar addition, residual glucose concentration in the broth was maintained below 1 g/L and cell‐growth rate was kept at constant at preset vaiues. The accuracy and reproducibility of this technique are demonstrated. The use of real‐time control of cell growth is expected to aid future investigations of this antibiotic fermentation.
Continuos IBE fermentation by immobilized growing Clostridium beijerinckii cells in a stirred‐tank fermentor
Authors: Krouwel P. G. , Groot W. J. , Kossen N. W. F. 
Published: December 2004

AbstractThe potential of continuous isopropanol–butanol–ethanol (IBE) fermentation by Ca–alginate‐immobilized Clostridium beijerinckii cells in a continuous stirred‐tank reactor is investigated. A mathematical model is presented to describe steady‐state reactor performance. It appeared to be possible to use the biocatalyst particles repeatedly for successive fermentations (at least three times for a total duration of two months). Reactor productivity was 6–16 times higher than that of a batch fermentation (free cells), while the solvents yield was also increased. Measurements of substrate, product, and biomass concentrations were only partially in agreement with the model; however, a solid basis for further technological developement of the process has been laid.
Permeabilities of composite membranes containing phospholipids
Authors: Sada Eizo , Katoh Shigeo , Terashima Masaaki 
Published: December 2004

AbstractTwo types of artificial membranes containing a phospholipid were prepared and their permeabilities were measured around the phase‐transition temperature of the phospholipid. The permeability of the membranes to a hydrophobic solute was higher than to a hydrophilic solute, and showed an abrupt change at the phase‐transition temperature of the phospholipid, similar to that in biomembranes and liposomes, caused by the fluidity change of the phospholipid at this temperature.
Production of Spirulina biomass: Maintenance of monoalgal culture outdoors
Authors: Vonshak A. , Boussiba S. , Abeliovich A. , Richmond A. 
Published: December 2004

AbstractThe effects of sodium bicarbonate concentration, population density, and temperature on the maintenance of an outdoor monoculture of the cyanobacterium Spirulina platensis were studied. A clear response by Spirulina to the concentration of bicarbonate was evident, with 0.2M bicarbonate representing the lowest concentration in which a monoculture could be maintained. When the temperatures fell during the winter period to some 20–25°C below the optimum for Spirulina, Chlorella sp. gradually increased and became the dominant species in the culture. Raising the temperature by covering the pond with transparent polyethylene resulted in a sharp decline in the population of Chlorella, and a gradual resumption of species dominance by Spirulina. In winter, there was an inverse relationship in the pond between the population density of Spirulina and the extent of contamination by Chlorella sp.; but no such effect was observed under field conditions at temperatures higher than 25°C.
Intensified controlled fish growth in tanks implementing a multipurpose flow device
Authors: Oron Gideon , Granoth Gila , Porath Dan 
Published: December 2004

AbstractFish biomass (Tilapia sp.) were raised at high stocking density in 1‐m3 tanks containing 450 L of water. The water was changed continously by means of a jet flow regulator. The jet flow regulator maintained adequate dissolved oxygen (DO) and a low ammonia level, while the suspended solids were discarded. In such a system, an annual yield of above 15 kg/m3 can be expected. The application of the jet flow regulator in aquaculture is discussed.
Pitfalls in the assay of carboxymethylcellulase activity
Authors: Lindner W. A. , Dennison C. , Quicke G. V. 
Published: December 2004

AbstractA purified endocellulase from Sclerotium rolfsii and a crude cellulase preparation from Trichoderma reesei are used to illustrate several pitfalls associated with the assay of carboxymethylcellulase activity and the subsequent attainment of linear enzyme dilution curves. It is shown that the nature of both the enzymes and the substrate make the assay unsuitable for use in the calculation of enzyme recovery and purity.
Continuous simultaneous saccharification and fermentation of starch using Zymomonas mobilis
Authors: Lee J. H. , Pagan R. J. , Rogers P. L. 
Published: December 2004

AbstractA continuous process involving simultaneous saccharification and fermentation of liquefied starch has been developed using Zymomonas mobilis. Amyloglucosidase retention and cell recycle have been effected by using an Amicon hollow‐fiber membrane system with a MW cutoff of 5000. Relatively high productivities of up to 60 g L−1 h−1 have been achieved at ethanol concentrations of 60–65 g/L. The system also offers the potential for reduced enzyme requirements for saccharification.
The performance of immobilized glucose isomerase supported by shrimp chitin in various types of reactors
Authors: Chen Fu‐Sen , Weng Hung‐Shan , Lai Ching‐Liang 
Published: December 2004

AbstractFive different types of reactors were employed for glucose isomerization using shrimp shell as the support on which to immobilize the glucose isomerase. The Michaelis–Menten constants and effective diffusivity of glucose in the immobilized enzyme bed were experimentally determined and used in a theoretical analysis of the radial‐flow reactor. The fractional conversions of the radial‐flow, fluidizedbed, and packed‐bed reactors with the same ‐residence time were found experimentally to be almost the same. This result reveals that the use of radial‐flow and fluidized‐bed reactors for this immobilized enzyme system is highly feasible.