bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of startup and operation of four anaerobic processes treating a synthetic meat waste
Authors: Stephenson Tom , Lester John N. 
Published: May 2005

AbstractTwo continuous stirred tanks reactors (CSTR) and four anaerobic fluidized bed reactors (AFBR) were used to study the treatment of a synthetic meat waste during single‐and two‐stage anaerobic treatment. Four configurations were investigated; a single‐stage CSTR and AFBR and the two‐stage systems CSTR–AFBR and AFBR–AFBR. Startup of the anaerobic reactors was achieved within 50 days by use of a regime that included stepped increases in influent COD, methanol substitution of the substrate, and addition of essential trace metals such as cobalt and nickel. Two‐stage reactors removed up to 85% of influent COD concentrations of 5000 mg/L, whereas the single‐stage AFBR and CSTR removed 76 and 9%, respectively. The proportion of methane in the effluent gases increased as the influent COD concentration was increased. Volumetric production of methane was greatest for the first stage of the AFBR–AFBR system. Solids retention times calculated for the AFBRs ranged from 7 to 12 days, sufficient to support methanogenesis. The AFBRs and two‐stage systems were more resistant to an influent pH shock from the operating value of pH 6.8 down to pH 3 than the CSTRs and single‐stage reactors. It was concluded that high‐rate anaerobic treatment systems were applicable to meat industry wastewaters and that two‐stage digestion produced a better quality effluent.
Enzymatic analyses in organic solvents
Authors: Kazandjian Rafi Z. , Dordick Jonathan S. , Klibanov Alexander M. 
Published: May 2005

AbstractHorseradish peroxidase has been found to vigorously act as a catalyst in a number of water‐immiscible organic solvents. The rates of peroxidase‐catalyzed oxidation of p–anisidine with H2O2 in toluene, benzene, ethyl and butyl acetates, and ether are in the range of 10–25% of that in water (pH 7.0) at the same reactant concentrations. Per oxidase was coupled with cholesterol oxidase (which was also found to be catalytically active in organic media), and the bienzymic system was successfully used for accurate, reliable, and reproducible determination of cholesterol in toluene.
Membrane separation of protein precipitates: Studies with cross flow in hollow fibers
Authors: Devereux N. , Hoare M. 
Published: May 2005

AbstractHollow fiber ultrafiltration and microfiltration membranes are examined for the processing of isoelectric soya protein precipitate suspensions. A model based on the various resistances to permeate flux is used to describe membrane performance. The main resistance to permeate flux is due to the interaction between the active membrane and the soluble and precipitated protein; that is, as compared with resistances due to the active membrane itself or the membrane support structure, or arising from concentrated soluble or precipitated protein layers over the membrane surface. Soluble protein rejection and precipitate mean particle diameter are correlated with observed values of this main resistance.In contract to the ultrafiltration of soluble proteins, the flux rates observed when processing protein precipitate suspensions under a similar range of operating conditions do not approach a limiting value with increased transmembrane pressure. At high protein concentrations, greater flux rates may be achieved for precipitated as compared with soluble proteins. The use of a microfiltration membrane does not give further improvement in flux rate; this may be attributed to problems of pore fouling with precipitate particles.
Immobilization of hydrogenase in nylon gel containing electron mediator and application to an artificial photosystem
Authors: Nosaka Yoshio , Kuwabara Atsushi , Kobayashi Takaomi , Miyama Hajime 
Published: May 2005

AbstractHydrogenase of Desulfovibrio vulgaris was immobilized in nylon gel containing an electron mediator. With the immobilization, the stability for storage and repeated use increased and the optimal pH was shifted to the acidic side. Photoinduced hydrogen production was observed in an artificial photosystem consisting of the hydrogenase gel, metal porphyrin, and mercaptethanol.
An integrated microprocessor‐based fermenter control system
Authors: Merrill Roy D. , Bauer Keith 
Published: May 2005

AbstractAn integrated microprocessor‐based fermenter controller was developed in 1980 for an operational environment at Cetus Corp. The main goals in the design and construction of the system were (1) to facilitate scale‐up; (2) to provide flexibility and high performance for optimizing fermentation processes; and (3) to be cost‐effective for 15 in‐house systems. It was also developed to work in conjunction with a laboratory minicomputer for on‐line optimization experiments. The controller controls temperature, agitation, dissolved oxygen, pH, and foam throughout each fermentation run without manual intervention. The feedback control parameters have been optimized to provide very accurate control over a wide range of setpoint conditions and under rapidly changing metabolic conditions such as induced during an Escherichia coli batch run. The controller has also been configured to monitor, display, and record each of the controlled variables; support the interactive operator console; and communicate with the laboratory computer. In over 4 years of operation, these systems have met the design goals and have proven to be very reliable. The controller is described, its operational performance presented, and a typical fermentation run delineated.
Studies on the thermal inactivation of immobilized enzymes
Authors: Ulbrich Renate , Schellenberger Alfred , Damerau Werner 
Published: May 2005

AbstractThe thermal inactivation of a great number of immobilized enzymes shows a biphasic kinetics, which distinctly differs from the first‐order inactivation kinetics of the corresponding soluble enzymes. As shown for α‐amylase, chymotrypsin, and trypsin covalently bound to silica, polystyrene, or polyacrylamide, the dependence of the remaining activities on the heating time can be well described by the sum of two exponential terms. To interpret this mathematical model function, the catalytic properties of immobilized enzymes (number of active sites in silica‐bound trypsin, KM and Ea values in silica‐bound α‐amylase and chymotrypsin) at different stages of inactivation and the influence of various factors (coupling conditions, addition of denaturants or stabilizers, etc.) on the thermal inactivation of silica‐bound α‐amylase were studied. Furthermore, conformational alterations in the thermal denaturation of spin‐labeled soluble and silica‐bound β‐amylase were compared by electron spin resonance (ESR) studies. The results suggest that the biphasic inactivation kinetics reflects two different pathways according to which catalytically identical enzyme molecules are predominantly inactivated.
Acetonobutylic fermentation: Improvement of performances by coupling continuous fermentation and ultrafiltration
Authors: Ferras E. , Minier M. , Goma G. 
Published: May 2005

AbstractThe technology of coupling ultrafiltration and fermentation has been tested with the acetonobutylic fermentation in continuous mode. The device developed was sterilizable by steam and permitted drastic cleaning of the ultrafiltration (UF) membrane without interrupting the continuous fermentation. It has been shown to be an easily operated and reliable experimental tool for studying high‐cell‐density cultures and inhibition phenomena. With total recycle of biomass, a dry weight concentration of 125 g/L was attained, which greatly enhanced the volumetric solvent productivity of acetonobutylic fermentation in averaging 4. 5 g/L h for significant periods of time (>70 h) and maintaining solvent concentration and yield at acceptable levels.
Elimination of ethanol inhibition by perstraction
Authors: Matsumura Masatoshi , Märkl Herbert 
Published: May 2005

AbstractPerstraction (membrane‐aided solvent extraction) was utilized for elimination of ethanol inhibition in continuous ethanol fermentation using high sugar concentrate. Hollow fibers for an artificial kidney were used as a permeable membrane, and their capacity to extract ethanol was examined by using several organic solvents. When tri‐n‐butylphosphate was used as an extractant, a 500 g/L feed glucose medium was successfully fermented by immobilized yeast cells. During this continuous fermentation a high ehtanol productivity of 48 g/h‐L‐gel was held, and the solvent requirement per consumed glucose was 6 L‐solvent/kg‐glucose.
Production of cellulase enzymes and hydrolysis of steam‐exploded wood
Authors: Martin R. San , Blanch H. W. , Wilke C. R. , Sciamanna A. F. 
Published: May 2005

AbstractSteam‐exploded aspen has been examined as a candidate feedstock for both cellulose production and enzymatic hydrolysis of wood. Batch and fed‐batch cultivation methods were evaluated and compared with previous experiments using ball‐milled, crystalline cellulose (Solka Floe). Batch cultivation of Trichoderma reesei Rut C‐30 on 9 wt% water‐washed aspen yielded enzyme productivities and activities comparable to those obtained on Solka Floe (40 FP IU/L–h; 7. 5 FP IU/mL). Fed‐batch cultivation of Rut C‐30 resulted in higher enzyme productivities and tilers than batch cultivation (50 FP IU/L–h; 15 FP IU/mL). However, the overall enzyme production performance was lower than on Solka Floe at comparable cellulose feeding rates and concentrations. This may be due to the accumulation of steam explosion by‐products and lignin in the fermentor.The hydroiysis of water‐washed steam‐exploded aspen was performed at different enzyme loadings and wood concentrations. Glucose production, using 10 and 15wt% suspension, showed that while glucose concentration increased with wood load, the yield of glucose derived from cellulose decreased. With 10wt% suspensions, it was possible to obtain a cellous conversion to glucose above 95%. Low cellulose levels in the hydrolyzates indicated that the filter paper activity ratios (approximately 1.5), a significant result since the fungus was grown exclusively on wood. mIt also suggested that the observed yield decrease is more likely to be caused by glucose than cellobiose inhibition of the enzymes.
Bubble coalescence in air‐sparged bioreactors
Authors: Oolman Timothy O. , Blanch Harvey W. 
Published: May 2005

AbstractCoalescence frequency has been measured in an air‐sparged bubble column by observing the rate with which insoluble tracer gases were mixed within the dispersed gas phase. The effects of gas‐sparge rate and salt concentration were examined. Coalescence frequencies increased with increasing gas‐sparge rates approximately in proportion to the increase in gas‐phase hold up. The coalescence frequency decreased with NaCI concentration to a minimum frequency about half the frequency observed in pure water. Bubble size distributions were also measured in the air‐sparged column. The size distribution changed significantly over the same range of NaCI concentration as variations in the coalescence frequency were observed. The gas‐sparge rate showed no effect on the bubble size.
Recent developments in hydrogen management during anaerobic biological wastewater treatment
Authors: Harper Stephen R. , Pohland Frederick G. 
Published: May 2005

AbstractA comprehensive review of the microbial kinetics, energetics, and substrate specificities of anaerobic waste‐water treatment systems is presented with descriptions of three different state‐of‐the‐art reactor configurations. Each of these reactor systems is intended to enrich different populations of anaerobic acidogens and methan‐ogens as a result of design and operational strategies for control of hydrogen and volatile acids. Imposition of these strategies results in different substrate utilization patterns, conversion kinetics, and operational stabilities as are currently being demonstrated in laboratory‐scale investigations.
On‐line adaptive control of a fed‐batch fermentation of Saccharomyces cerevisiae
Authors: Williams D. , Yousefpour P. , Wellington E. M. H. 
Published: May 2005

AbstractThe feasibility of applying an adaptive control technique to a fermentation process is investigated. The nonlinear, time‐variant parameters of a fermentation process were estimated on‐line as a series of linearized describing matrices. The matrices were used to update a suboptimal feedback law which controlled the process in real time over the linear region. Experiments were performed on a small‐scale fully instrumented fermenter with the online, real‐time adaptive control package. Results are presented for both single‐ and multivariable control, and indicate successful control of yeast cell growth.
Continuous hybridoma growth and monoclonal antibody production in hollow fiber reactors–separators
Authors: Altshuler Gordon L. , Dziewulski David M. , Sowek Judith A. , Belfort Georges 
Published: May 2005

AbstractGrowth of a hybridoma culture, along with production of monoclonal antibody, was demonstrated over extended periods in polysulfone hollow fiber membrane modules. The molecular weight cutoffs of the membranes were 70,000, 50,000, and 100,000 daltons. The hybridoma cell line, designated 65/26, produced IgG (2b/κ) directed at mouse thymus cell surface antigen, TL.1. Cell growth occurred in the shell space of the reactor, using supplemented RPMI 1640 (20% fetal bovine serum) supplied from a separate reservoir vessel through the hollow fiber lumen. The reservoir contained 125 mL media, which was changed every 4 days. Concentrations of immunoglobulin were determined by an enzyme immunoassay (using protein A and alkaline phosphatase‐labeled antibody conjugate). For the 10K, 50K, and 100K hollow fiber membrane modules, the maximum IgG concentrations detected in the 2.5‐mL shell space were 47.5–80, 510, and 740 μg/mL, respectively. In the 125‐mL reservoir for the 100K hollow fiber membrane module, the IgG concentration was measured at 260 μg/mL These values compare with an IgG concentration of 1 μg/mL when grown in a standard tissue culture flask and 3.2–7.6 μg/mL when grown in 100 ml media in a spinner flask. In addition, 10K and 50K hollow fiber membrane modules were run in a mode that decreased the fetal bovine serum supplement with time. Differences between these systems suggest that it is possible to obtain high IgG accumulation rates, both during and after the exponential growth phase of the hybridoma population.
Control of nitrate concentration in fermentations of Corynebacterium glutamicum
Authors: Kole M. M. , Thompson B. G. , Gerson Donald. F. , Senechal J. 
Published: May 2005

AbstractA nitrate control system has been devised for the maintenance of stable nitrate concentrations throughout fed‐batch fermentations of Corynebacterium glutamicum. The feedback control system was based on the use of a nitrate‐ion‐selective electrode to directly monitor the nitrate levels in the fermentor and an automatic controller to activate a nitrate feed pump. The electrode which was used for controlling the nitrate level was stable through‐out the fermentation period. The apparent maximum specific growth rate, biomass production, protein production, biomass yields on glucose and nitrate, and amino acid production were all optimal at approximately 50mM nitrate.
Effect of immobilization on the physical and kinetic properties of soluble and insoluble trypsin–albumin polymers
Authors: Cohenford Menashi A. , Santoro Peter F. , Urbanowski Joseph C. , Dain Joel A. 
Published: May 2005

AbstractBovine trypsin was crosslinked to human serum albumin (HSA) with glutaraldehyde to form soluble and insoluble copolymers. The physical and kinetic properties of trypsin and trypsin‐HSA polymers were compared. Trypsin was heat labile, retaining only 24% of its enzymic activity after heating for 5 min at 60°C. In contrast, under the same condition both the soluble and insoluble trypsin‐HSA polymers showed enhanced resistance to heat in‐activation, retaining 81 and 100% of their original activities, respectively. The trypsin‐HSA polymers also showed shifts in pH optima, an increase in activation energy, and a broadening of their pH stability profiles.
Morphology of yeast cell wall as affected by genetic manipulation of β(1 → 6) glycosidic linkage
Authors: Jamas Spiros , Rha ChoKyun , Sinskey Anthony J. 
Published: May 2005

AbstractThe morphology of yeast cells as it is affected by the glycosidic linkages of constituent glucan was studied. Four different strains of Saccharomyces cerevisiae were studied. A cell wall matrix particle representing the intact original morphology and composed entirely of β‐glucan was prepared. Using prepared cell wall glucan particles, the morphology and cell wall matrix structure were examined. Genetic modification of the cell wall structure during growth results in the alteration of the shape and hydrodnamic volume of the intact cell wall particles. The shape and hydrodynamic volume of the cell wall particles can also be modified by in vitro chemical and enzymatic treatment. The shape factor and hydrodynamic volume of the whole glucan cell wall matrix particles were evaluated quantitatively using a rheological analysis. An increased degree of β(1 → 6) cross‐linking in the cell wall matrix induces a nearly 2‐fold increase in the shape factor and a 10‐fold increase in the compression modulus of the glucan particles. The disruption of β(1 → 6) glycosidic cross‐linking causes the particles to swell by up to 18% of their original volume. This was used as a strategy to isolate a yeast mutant with a high β(1 → 6) glycosidic content in the cell wall glucan.
Design of fluidized‐bed fermentors
Authors: Andrews G. F. , Przezdziecki J. 
Published: May 2005

AbstractDesigning a fluidized‐bed bioreactor requires choosing the best support particle (if any). Effectiveness factors (proportional to reactor volumetric productivity) are derived for flocs, solid spherical supports, porous supports, and adsorbent supports. The derivation demonstrates a mathematical procedure for reducing the diffusion/uptake equations for many components (substrates and inhibitory products) to a single equation, and for identifying the limiting component. With solid supports there exists a film thickness that maximizes the effectiveness, and the design objective is to keep the film near this optimum throughout the bed. This involves consideration of the effect of support particle density and film growth on bed stratification. Other considerations in picking support particles are obtaining reasonable values for bed height and diameter, minimizing mass transfer resistance between liquid and biomass, and preventing surface shear from stripping off the biomass.
Effect of temperature and pH on immobilized Zymomonas mobilis for continuous production of ethanol
Authors: Bajpai Pramod K. , Margaritis Argyrios 
Published: May 2005

AbstractThe effects of temperature and inlet pH of the medium on the ethanol productivity and activity of the immobilized Z. mobilis cells during continuous fermentation of glucose have been studied at various temperatures and pH. On changing the temperature from one steady state level to a new one, 6–8 h were required in order to fully experience the effect of a change in temperature; whereas 8–20 h were required on changing the pH. The optimum temperature of 37°C and a broad pH range of 4.4–6.0 were observed for maximum ethanol productivity and ethanol yield.
Continuous production of thienamycin in immobilized cell systems
Authors: Arcuri E. J. , Slaff G. , Greasham R. 
Published: May 2005

AbstractA novel 2‐L bubble column was used to study the continuous, immobilized cell production of thienamycin. Cells of Streptomyces cattleya were immobilized by culturing them in an appropriate growth medium containing 60/80 mesh celite particles. The dilution rate used during the continuous growth phase was 0.2 h−1. This growth phase was terminated upon the development of heavy cell films (100–500 μm thickness), and the medium was replaced with an appropriate thienamycin production medium. The system was then operated in a batch mode until thienamycin production began. At that time, continuous feeding of the production medium was initiated and the influence of medium composition and dilution rate on CO2, NH4, biomass, and thienamycin production investigated. With synthetic production medium, a doubling of the dilution rate from 0.05 to 0.10 h−1 resulted in a doubling of the thienamycin volumetric productivity. Rates of CO2 and NH4 production increased by ca. factors of three and two, respectively. The rate of PO4 utilization also doubled. When the dilution rate was decreased to 0.05 h−1, the rates of CO2 production and PO4 utilization quickly decreased (i.e., within 3 h). The rates of NH4 and thienamycin production also decreased but more slowly (i.e., ca. 100 h after the decrease in dilution rate). With complex production medium, the rates of CO2 production and PO4 utilization appeared to be a direct function of dilution rate at the dilution rates tested. Thienamycin production in this case was not a function of dilution rate. Comparing the synthetic medium with the complex medium at either dilution rate, the volumetric rate of thienamycin production was higher in the system being fed complex medium. However, the specific activity (units thienamycin/g cell/h) observed with complex medium was lower than that observed with synthetic medium. The higher volumetric productivity observed with complex medium was the result of a high cell loading. The above observations will be discussed in terms of control of thienamycin synthesis and film thickness effects.
Synergism of endoenzyme and exoenzyme on hydrolysis of soluble cellulose derivatives
Authors: Fujii Michihiro , Shimizu Masami 
Published: May 2005

AbstractA kinetic model that represents the reaction of hydrolysis of water‐soluble cellulose derivatives by a mixed endo‐ and exoenzyme system is proposed with the following assumptions: at an early stage of the reaction, endoenzymes split the substrate molecule in order to supply the newly formed nonreducing ends to exoenzymes until the molecular weight of the substrates reaches a low value; after that point, the reaction kinetics obeys only the rate equation of the reaction of the exoenzymes in which the reaction parameters change linearly with decrease of the molecular weight of the substrates. Hydrolysis experiments of soluble cellulose derivatives, carboxymethyl cellulose and hydroxyethyl cellulose, were carried out with endo‐and exoenzymes separated from Trichoderma Koningii cellulase. The critical molecular weight of the substrate, from that point the action of endoenzyme can be neglected, was determined from the experimental data. That was ca. 4000 D. With that value, the model fits well the experimental data. Synergism of both enzymes appears as enhancement of the rate of the reaction at the early stage of the reaction.
Fermentation kinetics of spent sulfite liquor by Saccharomyces cerevisiae
Authors: Safi B. F. , Rouleau D. , Mayer R. C. , Desrochers M. 
Published: May 2005

AbstractThe growth kinetics of the yeast Saccharomyces cerevisiae and the production rate of ethanol have been studied in batch fermentation under anaerobic conditions in a 20‐L fermentor. Two substrates were used in fermentation trials: a synthetic mixture of three fermentable sugars, D‐glucose, D‐mannose, and D‐galactose, and a low‐yield liquor originating from a bisulfite cooking process. The Monod model adequately described the system in relation to the specific growth rate μx and the specific product formation rate μP. Different fermentation parameters (growth rate, substrate utilization, and product formation) were determined for the synthetic mixture and the bisulfite liquor. It was observed that the specific growth rate is much lower in spent sulfite liquor than in a synthetic medium. However, the specific product formation rate remains the same in both media.