bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐Rate two‐phase process for the anaerobic degradation of cellulose, employing rumen microorganisms for an efficient acidogenesis
Authors: Gijzen Huub J. , Zwart Kor B. , Verhagen Frank J. M. , Vogels Godfried P. 
Published: December 2004

AbstractA novel two‐stage anaerobic process for the microbial conversion of cellulose into biogas has been developed. In the first phase, a mixed population of rumen bacteria and ciliates was used in the hydrolysis and fermentation of cellulose. The volatile fatty acids (VFA) produced in this acidogenic reactor were subsequently converted into biogas in a UASB‐type methanogenic reactor.A stepwise increase of the loading rate from 11.9 to 25.8 g volatile solids/L reactor volume/day (g VS/L/day) did not affect the degradation efficiency in the acidogenic reactor, whereas the methanogenic reactor appeared to be overloaded at the highest loading rate. Cellulose digestion was almost complete at all loading rates applied. The two‐stage anaerobic process was also tested with a closed fluid circuit. In this instance total methane production was 0.438 L CH4g VS added, which is equivalent to 98% of the theoretical value. The application of rumen microorganisms in combination with a high‐rate methane reactor is proposed as a means of efficient anaerobic degradation of cellulosic residues to methane. Because this newly developed two‐phase system is based on processes and microorganisms from the ruminant, it will be referred to as “Rumen Derived Anaerobic Digestion” (RUDAD‐) process.
Characterization of fractionated polyclonal antibodies for immunoaffinity chromatography
Authors: Sada Eizo , Katoh Shigeo , Kiyokawa Atsuo , Kondo Akihiko 
Published: December 2004

AbstractPolyclonal anti‐BSA antibodies were ractionated by stepwise elution from an immobilized BSA column by decreasing pH or increasing the concentration of NaSCN. The binding affinities of each fraction and original globulin under physiological conditions and their dependence on pH and ionic environments were compared. Fractions with high association constant under physiological conditions did not necessarily show antigen binding affinity over a wide pH range, but they retained a high affinity at higher ionic strength of NaSCN. Consequently, by combining these two fractionation procedures, a fraction with high affinity and which dissociated at moderate pH was obtained. It is clear that high affinity is not always incompatible with ease of dissociation accompanying a change in conditions.
Activated sludge systems with biomass particle support structures
Authors: Nicol Jean‐Paul , Benefield Larry D. , Wetzel Edward D. , Heidman James A. 
Published: December 2004

AbstractA mathematical model was developed to simulate the operation of an activated sludge system with biomass support particles. Based on the results of this simulation study, it would appear that a system with biomass particle supports offers several advantages not offered by conventional systems. These include the ability to resist failure from large hydraulic surges; stable nitrification under transient inhibitory conditions resulting from temperature changes, hydraulic surges, and/or toxic chemicals; and the ability to establish stable operating conditions with respect to both carbon oxidation and nitrification at short hydraulic retention times and low sludge ages.
Preparation and activity of carbonic anhydrase immobilized on porous silica beads and graphite rods
Authors: Crumbliss A. L. , McLachlan K. L. , O'Daly J. P. , Henkens R. W. 
Published: December 2004

AbstractTechniques for the immobilization of bovine carbonic anhydrase (BCA) on porous silica beads and graphite are presented. Surface coverage on porous silica beads was found to be 1.5 × 10−5 mmol BCA/m2, and on graphite it was 1.7 × 10−3 mmol BCA/m2 nominal surface area. Greater than 97% (silica support) and 85% (graphite support) enzyme activity was maintained upon storage of the immobilized enzyme for 50 days in pH 8 buffer at 4°C. After 500 days storage, the porous silica bead immobilized enzyme exhibited over 70% activity. Operational stability of the enzyme on silica at 23°C and pH 8 was found to be 50% after 30 days. Catalytic activity expressed as an apparent second‐order rate constant K′Enz for the hydrolysis of p‐nitrophenyl acetate (p‐NPA) catalyzed by BCA immobilized on silica beads and graphite at pH 8 and 25°C is 2.6 × 102 and 5.6 × 102 M−1s−1 respectively. The corresponding KENZ value for the free enzyme is 9.1 × 102 M−1s−1. Activity of the immobilized enzyme was found to vary with pH in such a manner that the active site pK, on the porous silica bead support is 6.75, and on graphite it is 7.41. Possible reasons for a microenvironmental influence on carbonic anhydrase pKa, are discussed. Comparison with literature data shows that the enzyme surface coverage on silica beads reported here is superior to previously reported data on silica beads and polyacrylamide gels and is comparable to an organic matrix support. Shifts in BCA‐active site pKa values with support material, a lack of pH dependent activity studies in the literature, and differing criteria for reporting enzyme activity complicate literature comparisons of activity; however, immobilized BCA reported here generally exhibits comparable or greater activity than previous reports for immobilized BCA.
Increased digestibility of cedar by pretreatment with peracetic acid and steam explosion
Authors: Ando Shingo , Kakimoto Takahiro , Itoh Kazuyoshi , Arai Isamu , Kiyoto Koichi , Hanai Shiro 
Published: December 2004

AbstractA type of steam explosion method combined with chemical pretreatment was studied. Peracetic acid was an effective reagent to assist the steam explosion reaction and greatly improved the enzymatic saccharification of cedar compared with single steam explosion. The extent of saccharification was directly proportional to the amount of peracetic acid absorbed in the chips, and the function of peracetic acid was revealed as an acid catalyst and as a radical initiator in the steam explosion reaction.
Inhibiting action of chlorophenols on biodegradation of phenol and its correlation with structural properties of inhibitors
Authors: Beltrame Paolo , Beltrame Pier Luigi , Carniti Paolo , Guardione Donatella , Lanzetta Cecilia 
Published: December 2004

AbstractAn activated sludge conditioned to a low concentration of phenol was used for the biodegradation of phenol in the presence of Chlorophenols, measuring the inhibiting action of all the latter compounds and expressing it as p/50. As a structural property to be correlated with the measured values, the lipophilicity (log P) of the Chlorophenols was reevaluated with a new apparatus. Values of p/50p are better correlated with the number of chloro substituents in the inhibitor, provided a specific effect of substituents ortho to the phenolic function is considered. New results are compared with previous measurements effected on a different activated sludge.
Repeated batch production of L‐phenylalanine from phenylpyruvate and NH4Cl by immobilized cells of Nocardia opaca under hydrogen high pressure
Authors: Matsunaga Tadashi , Higashijima Michio , Sulaswatty Anny , Nishimura Shigeo , Kitamura Takanori , Tsuji Masao , Kawaguchi Toshio 
Published: December 2004

AbstractAmong various microbial cells examined under screening conditions, Nocardia opaca showed the highest activity for production of phenylalanine from phenylpyruvate. Here NH4Cl as well as amino acids were used as an amino donor for phenylalanine production. The phenylalanine production rate increased with increasing hydrogen pressure. The specific activity of phenylalanine dehydrogenase was increased by culturing N. opaca cells in nutrient broth containing 0.3% phenylalanine. As a result, the phenylalanine production rate increased from 0.69 to 4.4 μmol/min g dry cells. Immobilized cells were activated in nutrient broth containing ZnCl2 before phenylalanine production. Phenylalanine dehydrogenase activity and cell number in the gel increased with increasing incubation time, and the maximum phenylalanine dehydrogenase activity was obtained at 36 h incubation. Then, phenylalanine was produced from phenylpyruvate, NH4Cl, and 100 atm H2 with the activated immobilized cells. The rate of phenylalanine production was 0.24 μmol/min cm3 gel. The conversion of phenylpyruvate to phenylalanine was 82%. Immobilized cells retained 76% of the initial phenylalanine production rate after 10 h reactions were repeated 11 times with two intervening reactivations.
Protein precipitate recovery using microporous membranes
Authors: Bentham A. C. , Ireton M. J. , Hoare M. , Dunnill P. 
Published: December 2004

AbstractThe use of microporous membranes has been examined for the recovery of precipitated protein suspensions and related soluble protein. Membrane flux rates and soluble protein transmissions are reported for unstirred batch‐cell studies and cross‐flow experiments. The unstirred batch‐cell gave soluble protein transmissions in the range 80–100% for feeds containing either soluble protein or a mix of soluble and isoelectrically precipitated protein. In all cases a sharp decline in flux was observed which was, for example, considerably greater for soluble protein at its isoelectric point, pH 4.6, than at pH 8.8. The presence of precipitated protein led to a further decrease in flux rate. In cross‐flow studies, flux decline was eventually accompanied by a significant decline in soluble protein transmission. The flux protein‐transmission characteristics of microporous membranes are discussed in terms of the interaction of the soluble and precipitated protein with the membrane.
Effects of carbon dioxide on Penicillium chrysogenum: An autoradiographic study
Authors: Edwards Alfred G. , Ho Chester S. 
Published: December 2004

AbstractPrevious research has shown that dissolved carbon dioxide causes significant changes in submerged penicillin fermentations, such as stunted, swollen hyphae, increased branching, lower growth rates, and lower penicillin productivity. Influent carbon dioxide levels of 5 and 10% were shown through the use of autoradiography to cause an increase in chitin synthesis in submerged cultures of Penicillium chrysogenum. At an influent 5% carbon dioxide level, chitin synthesis is ca. 100% greater in the subapical region of P. chrysogenum hyphae than that of the control, in which there was no influent carbon dioxide. Influent carbon dioxide of 10% caused an increase of 200% in chitin synthesis, it is believed that the cell wall must be plasticized before branching can occur and that high amounts of dissolved carbon dioxide cause the cell to lose control of the plasticizing effect, thus the severe morphological changes occur.
Correlation of cell volume fractions with cell concentrations in fermentation media
Authors: Ju Lu‐Kwang , Ho Chester S. 
Published: December 2004

AbstractCell volume fractions and cell concentrations were measured in submerged cultures of Saccharomyces cerevisiae, Escherichia coli, and Penicillium chrysogenum. Correlations for cell volume fractions with cell concentrations in fermentation media of the microorganisms were established accordingly. Other key properties of microorganisms, such as cell water content, wet cell density, and dry cell density, can also be obtained with the use of the current method. The results are in good agreement with data available in the literature.
Application of fed‐batch culture to citric acid production by Aspergillus niger: The effects of dilution rate and dissolved oxygen tension
Authors: Dawson M. W. , Maddox I. S. , Boag I. F. , Brooks J. D. 
Published: December 2004

AbstractStudies in conventional batch culture confirmed that the maximum citric acid production rate occurred prior to exhaustion of the growth‐limiting nutrient, i.e., when the growth rate was nonzero. The effects of dilution rate and the culture dissolved oxygen tension (DOT) were studied in chemostat culture. Maximum citric acid yield and production rate were observed at low dilution rate (0.017 h−1) and high DOT value (90% of saturation). These findings were applied to a nitrogen‐limited fed batch culture, and allowed a productivity increase of 100% when compared with conventional batch culture.
Fermentation of corn starch to ethanol with genetically engineered yeast
Authors: Inlow D. , McRae J. , Ben‐Bassat A. 
Published: December 2004

AbstractExpression of the glucoamylase gene from Aspergillus awamori by laboratory and distiller's strains of Saccharomyces cerevisiae allowed them to ferment soluble starch. Approximately 95% of the carbohydrates in the starch were utilized. Glycerol production was significantly decreased when soluble starch was used instead of glucose. Ethanol yield on soluble starch was higher than that on glucose. The rate of starch fermentation was directly related to the level of glucoamylase activity. Strains with higher levels of glucoamylase expression fermented starch faster. The decline in starch fermentation rates toward the end of the fermentation was associated with accumulation of disaccharides and limit dextrins, poor substrates for glucoamylase. The buildup of these products in continuous fermentations inhibited glucoamylase activity and complete utilization of the starch. Under these conditions maltose‐fermenting strains had a significant advantage over nonfermenting strains. The synthesis and secretion of glucoamylase showed no deleterious effects on cell growth rates, fermetation rates, and fermentation products.
Modeling, optimization, and computer control of the cephalosporin C fermentation process
Authors: Chu Wey‐Bang Z. , Constantinides Alkis 
Published: December 2004

AbstractIn this study, a cephalosporin C producing strain, Cephalosporium acremonium (ATCC 36225), was chosen to determine the optimal conditions that maximize antibiotic production in a mixed substrate of glucose and sucrose. A model for cell growth and cephalosporin C production at different pH and temperature was developed and the associated parameters were evaluated experimentally. Pontryagin's maximum principle, in conjunction with the model, was used to predict the optimal temperature and pH control profiles to maximize the production of antibiotic.
Scaleup of monoclonal antibody purification using radial streaming ion exchange chromatography
Authors: Jungbauer A. , Unterluggauer F. , Uhl K. , Buchacher A. , Steindl F. , Pettauer D. , Wenisch E. 
Published: December 2004

AbstractA scaleup study of the radial streaming chromatography (ZetaPrep technique) using hybridoma culture supernatant as model protein solution is described in this article. Lab and pilot cartridges were tested. Scaleup factors were calculated from the lab experiments and compared to the data obtained at pilot level. The procedure consists of three different steps: microfiltration, diafiltration, and the ZetaPrep technique using QAE cartridges. Diafiltration was used to condition the clarified culture supernatant. Calculating the elution volumes for the pilot level (ZetaPrep 800) from the smallest lab cartridge (ZetaPrep 15), a difference between calculated and experimental values of 230% was obtained. The difference between calculated and experimental values using results from ZetaPrep 100, a preparative cartridge, was 120%. At pilot level it is possible to purify 10 L culture supernatant within 3 h including regeneration and reequilibration of the cartridge. This procedure is useful for monoclonal antibodies (mAb) with a low isoelectric point (pl). The pl's of the mAb which was used in this work are in the range 5.4–6.1.
Enzymatic hydrolysis of lignocellulosic biomass from Onopordum nervosum
Authors: Martín C. , Negro M. J. , Alfonsel M. , Sáez R. 
Published: December 2004

AbstractSome properties of the cellulolytic complex obtained from Trichoderma reesei QM 9414 grown on Solka floc as carbon source and its ability to hydrolyze the lignocellulosic biomass of Onopordum nervosum Boiss were studied. The optimum enzyme activity was found at temperatures between 50 and 55°C and pH ranging from 4.3 to 4.8. Hydrolysis of 4‐nitropnenyl‐β‐D‐glucopyranoside (4‐NPG) and cellobiose by the β‐glucosidase of the complex, showed competitive inhibition by glucose with a Ki value of 0.8 mM for 4‐NPG and 2. 56 mM for cellobiose. Enzymatic hydrolysis yield of Onopordum nervosum, evaluated as glucose production after 48 h, showed a threefold increase by pretreating the lignocellulosic substrate with alkali. When the loss of glucose incurred by de pretreatment was taken into account, a 160% increase in the final cellulose to glucose conversion was found to be due to the pretreatment.
Mathematical descriptions of hybridoma culture kinetics: I. Initial metabolic rates
Authors: Glacken M. W. , Adema E. , Sinskey A. J. 
Published: December 2004

AbstractThe lack of quantitative descriptions of mammalian culture kinetics limits the ability to optimally design and control cell culture bioreactors. This limitation is ad dressed by developing mathematical equations relating the initial growth rate and the antibody productivity of the hybridoma cell line, CRL‐1606, to its environmental state. This initial rate approach, in contrast with steady state analysis of chemostat cultures, approximates steady state behavior, since the rates were measured over brief time intervals and at low cell concentrations (< 50,000 cells/mL). The advantage of this approach is that it is much faster than the chemostat approach.An equation for the growth rate was developed that superimpoed Monod equations in serum and glutamine with “noncompetitive” ‐type inhibition constants were inversely proportional to the lactate and ammonium concentrations. The Monod constant is critical for relating initial, low cell level culture states to other states.Lactate was found to be the only environmental parameter that significantly inhibited antifibronectin monoclonal antibody production by the CRL‐1606 hybridimas. Volumetric productivity was strictly related to culture viability, which was observed to decline at growth rates below 0.02h−1. Lactate was also found to significantly inhibit ammonium production.
Synthesis of aspartame precursor: α‐L‐aspartyl‐L‐phenylalanine methyl ester in ethyl acetate using thermolysin entrapped in polyurethane
Authors: Yang Chin‐Pin , Su Chein‐Shyong 
Published: December 2004

AbstractCross‐linked polyurethane (PU) was prepared for entrapping thermolysin. Using the immobilized thermolysin (IT), Z‐L‐aspartic acid (ZA) was reacted with ‐Lphenylalanine methyl ester (L‐PM) in water‐saturated ethyl acetate to give only α‐Z‐L‐aspartylL‐phenylalanine methyl ester (α‐ZAPM). Ninety‐four percent conversion of α‐ZAPM was obtained for 30 h of reaction at 40°C when 46 mg of enzyme was entrapped. PU support prepared from polypropylene glycol (#2000) showed better properties than from polypropylene (#1000) and polyethylene (#1000). Addition of polyol could increase the gel fraction of PU. The IT PU‐ll‐G‐3, prepared from 1/2 mole ratio of PPG (#2000)/glycerin, gave the highest gel fraction and best swelling, and 89.0% of residual activity was obtained after four times of reuse (72 h). The stability of immobilized thermolysin was good; the activity loss resulting from degradatin and leak of enzyme in each time of reuse were found only about 2%. The kinetics of immobilized thermolysin‐catalyzed condensation reaction of ZA with L‐PM in water‐saturated ethyl acetate was found to be first order in L‐PM and the Lineweaver‐Burk plot of 1/V against 1/[ZA] yields a straight line, showing that the reaction involves consecutive reactions of ZA and L‐PM with the immobilized enzyme and with the ZA‐immobilized enzyme complex, with the second reaction being the rate determining step.
Separation and concentration of amino acids using liquid emulsion membranes
Authors: Thein M. P. , Hatton T. A. , Wang D. I. C. 
Published: December 2004

AbstractThe separation and concentration of amino acids using liquid emulsion membranes (LEMs) are discussed. Using L‐ phenylalanines as a model solute, it is experimentally shown using a facilitated transport system that separation and concentration can be simultaneously achieved. The rate of separation, final product concentration, and membrane swell are shown to increase with increasing chloride driving forces in the membrane, These effects are shown to be insensitive to the particular salt used as the driving force. Changes in the carrier concentration are shown to result in higher initial fluxes and higher swell rates. Hydrodynamically induced membrane breakage is minimal for the system under consideration. Experiments indicate that osmotically induced water transport (“swelling”) in the LEM system is mediated by both the carrier and the emulsion‐stabilizing surfactant. The data suggest that this swell is a diffusion‐limited process. The specificity of the carrier is examined and is found to be directly related to the hydrophobicity of the solute. Strategies for optimizing LEM formulations are discussed. Emphasis is placed on the hydration characteristics of the surfactant and the specificity of the carrier.
A numerical evaluation of a hollow fiber extractive fermentor process for the production of ethanol
Authors: Naser Samer Fahim , Fournier Ronald L. 
Published: December 2004

AbstractThe economics of a process for the production of ethanol employing a hollow fiber extractive fermentor have been investigated. A computer simulation of the process incorporating a mathematical model of the fermentor was used to calculate the mass and energy balances. The results of the process simulation were read into a computer spreadsheet programmed with the economic calculations from which a final ethanol product cost was obtained. The process was found to be as competitive as conventional fermentation processes even at the currently high cost — $4/sq ft — of hollow fibers. It was determined that the 1986 price of 46.2 cents/L of ethanol produced by the process would be reduced by 1.8 cents/L for every $1/sq foot drop in the price of hollow fibers. A comparison of this process with conventional fermentation processes indicates that its potential savings lie in its ability to use a concentrated sugar feed, and the fermentor's increased productivity and ability to produce a concentrated ethanol stream which is removed by the extracting solvent.
Release of periplasmic enzymes and other physiological effects of β‐lactamase overproduction in Escherichia coli
Authors: Georgiou George , Shuler Michael L. , Wilson David B. 
Published: December 2004

AbstractWhen Escherichia coli containing the plasmid ptac11 is induced with 10−4 M isopropyl‐β‐thiogalactopyranoside (IPTG), 90% of the β‐lactamase activity of an overnight culture is present in the medium. The high extracellular activity of β‐lactamase does not result from cell lysis but from an increase in the permeability of the outer membrane. The excreting cells release several other periplasmic enzymes into the extracellular fluid and are more sensitive to lysis by detergents. It was also shown that in these cells the level of two membrane proteins, OmpA and OmpC, is decreased. None of these phenomena were observed with the plasmid pDW17, which has a mutation in the tac promoter that reduces its activity to one fourth of the tac promoter.