bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a culture medium for large‐scale production of cellulolytic enzymes by Trichoderma reesei
Authors: Warzywoda M. , Ferre V. , Pourquie J. 
Published: December 2004

AbstractCulture filtrates of CL‐847 strain of Trichoderma reesei grown on different carbon sources have been compared. The highest enzyme production is obtained with Whatman C 41 cellulose: 17.9 mg/mL of soluble proteins and 13.7 units of filter paper (FP) activity. Wood pulps gave lower production values and more viscous culture media. About one‐third of maximal enzyme production is obtained on lactose as the sole carbon source. Addition of 0.5% cellulosic inducer to 6% lactose media enhances enzyme production up to the following levels: 14.1 mg/mL of soluble proteins and 8.4 units of FP activity.
A generalized kinetic model for the study of microbial growth
Authors: Hiss Haroldo , Borzani Walter 
Published: December 2004

AbstractThe following general equation is proposed to represent the kinetics of microbial growth

,
where ϕ and ψ depend on several parameters of the fermenting system. The values of ϕ and ψ were calculated based on results obtained in a batch lactic acid fermentation, a batch cultivation of yeast on diesel oil, and a continuous cultivation of yeast on sugarcane molasses.
Adsorption of cellulase from Trichoderma viride on cellulose
Authors: Ooshima Hiroshi , Sakata Masaru , Harano Yoshio 
Published: December 2004

AbstractThe adsorption of cellulase from Trichoderma viride (Meicelase CEP) on the surface of pure cellulose was studied. The adsorption was found to obey apparently the Langmuir isotherm. From the data concering the effects of temperature and the crystallinity of cellulose on the Langmuir adsorption parameters, the characteristics of the adsorption of the individual cellulase components, namely CMCase (endoglucanase) and Avicelase (exoglucanase), were discussed. While β‐glucosidase also adsorbed on the surface of cellulose at 5°C, it did not at 50°C.
Biological oxidation of organic constituents in tar–sand combustion‐process water
Authors: Torpy M. F. , Luthy R. G. , Raphaelian L. A. 
Published: December 2004

AbstractA study was performed to characterize a sample of reverse‐forward, tar‐sand combustion process water, and to conduct an initial evaluation of activated sludge treatment of the process water. No pretreatment of the wastewater was considered necessary prior to biological oxidation other than addition of ca. 0.006M caustic/L influent to maintain reactor pH in the desired range of 7.0–7.5. The process water was treated successfully by biological oxidation, achieving an 88% reduction of both COD and soluble organic carbon and a 97% reduction of BOD. The disposition of about 150 organic compounds was evaluated and it was shown that a variety of carboxylic acids and aromatic compounds were removed by treatment. Quinolines and certain higher molecular weight carboxylic acids were not removed as effectively as other compounds. These preliminary results should assist in the design of future investigations with tar‐sand process water for purposes of optimizing process treatment and improving sample characterization.
Preparative resolution of D,L‐threonine catalyzed by immobilized phosphatase
Authors: Scollar Mark P. , Sigal George , Klibanov Alexander M. 
Published: December 2004

AbstractHydrolysis of L‐ and D‐O‐phosphothreonines catalyzed by four different phosphatases, alkaline phosphatases from calf intestine and E. coli and acid phosphatases from wheat germ and potato, has been kinetically studied. Alkaline phosphatases were found to have comparable reactivities towards the optical isomers. On the other hand, both acid phosphatases displayed a marked stereoselectivity, hydrolyzing the L‐ester much faster than its D counterpart. Wheat germ acid phosphatase was the most stereoselective enzyme: VL/VD = 24 and Km,L/Km,D = 0.17. This enzyme was immobilized (in k‐carrageenan gel, followed by crosslinking with glutaraldehyde) and used for the preparative resolution of D,L‐threonine: the latter was first chemically O‐phosphorylated and then asymmetrically hydrolyzed by the immobilized phosphatase. As a result, gram quantities of L‐threonine of high optical purity and O‐phospho‐D‐threonine were prepared. Immobilized wheat germ phosphatase has been tested for the resolution of other racemic alcohols: serine, 2‐amino‐1‐butanol, 1‐amino‐2‐propanol, 2‐octanol, and menthol. In all those cases, the enzyme was either not sufficiently stereoselective or too slow for preparative resolutions.
Mathematical simulation of pseudo‐crystallofermentation of hydrocortisone by Arthrobacter simplex
Authors: Chen Kuo‐Cheng , Chang Ching‐Chuan , Chiu Chuang‐Fan , Ling Alvin C. 
Published: December 2004

AbstractA mathematical model has been developed to simulate the pseudo‐crystallofermentation process of hydrocortisone by Arthrobacter simplex. The model describing the process included considerations on the kinetics of microbial growth, the rate of enzyme formation, the rate of substrate dissolution, the rate of solute crystallization, and the kinetics of enzymatic reaction. The system of equations was solved numerically by the Runge‐Kutta‐Gill method. The good agreement between prediction and experiment indicated the reliability of the established model. The simulation was capable of predicting the time when the crystallization of product occurred, which could be further verified by microscopic observation on the culture medium, as well as cell growth, enzyme synthesis, product formation, and the composition of the final product crystals.
Enzymatic hydrolysis and fermentation of corn for fuel alcohol
Authors: Mullins J. Thomas 
Published: December 2004

AbstractThe integration of enzyme saccharification with fermentation reduces the total time required to produce acceptable levels of ethanol. The use of a more concentrated mash (84.8 L total mash/bu corn) results in a 26.6% increase in ethanol productivity and a 21.4% increase in beer ethanol concentration compared to standard corn mash (96.6 L total mash/bu corn). Thus, the energy requirement and cost of distillation can be reduced. The addition of waste cola syrup at 30 g invert sugar/L total mash gave a 19% increase in ethanol concentration in the final beer and required only a small increase in the period of fermentation. Surplus laundry starch can replace 30–50% of the weight of corn normally used in fermentation without influencing ethanol production or the time required for fermentation. Both of these waste materials reduce the unit cost of ethanol and demonstrate the value of such substances in ethanol systems.
Effect of different gas environments on bench‐scale solid state fermentation of oat straw by white‐rot fungi
Authors: Levonen‐Munoz Eeva , Bone Derek H. 
Published: December 2004

AbstractThree white‐rot fungi, Phanerochaete chrysosporium, Polyporus tulipiferae, and Polyporus sp. A336 were grown on 100‐g amounts of chopped oat straw in gassed 4.5 L (diameter 16 cm, height 23 cm) solid‐state reactors for two weeks. The different gas atmospheres were regulated by (1) air diffusion through foam plugs, (2) intermittent or continuous air flow, (3) intermittent oxygen, 50 or 100% continuous oxygen flow, and (4) continuous 10% carbon dioxide in oxygen flow. The fermented straw was analyzed for total weight loss, Klason lignin loss, and enzymatic (cellulase) hydrolysis. P. chrysosporium grown on straw in continuous oxygen at 35°C caused a 41% weight loss and 33.5% hydrolysis was obtained when the pretreated straw was hydrolyzed with cellulase enzyme. P. tulipiferae caused a 27% weight loss and 34.3% cellulase hydrolysis in the straw at 30°C. Polyporus sp. A336 selectively degraded lignin of the straw and under intermittent oxygen resulted in an 18% weight loss and 33.6% cellulase hydrolysis at 35°C. When the straw was supplemented with 10% xylose (straw basis) and was continuously gassed with 50% oxygen, Polyporus sp. A336 produced a 14.5% weight loss and 38.7% cellulase hydrolysis. Oxygen and carbon dioxide exchange rates were measured for some of these bench‐scale fermentations.
Studies on chemically aggregated pepsin using glutaraldehyde
Authors: Khan Seemi S. , Siddiqi A. M. 
Published: December 2004

AbstractPorcine pepsin was immobilized by chemical aggregation using glutaraldehyde as a bifunctional crosslinking agent. The immobilzed pepsin followed Michaelis–Menten kinetics (Km = 5.3 × 10−5 M) and the yield of immobilization was 91%. The activation energy of the immobilized preparation was 90,613 cal/mol as compared to 67,532 cal/mol for native pepsin. Using acid‐denatured hemoglobin and N‐acetyl phenyl‐alanyl‐3, 5‐diiodotyrosine (APDT) as substrates, the activities shown by the immobilized pepsin were, respectively, 67 and 79% that of the soluble pepsin. The immobiized pepsin showed marked stabilization against pH, temperature, urea, and guanidine hydrochloride. The activity of the immobilized preparation in the presence of urea was greater when hemoglobin was used as the substrate than when APDT was used as substrate. Storage of the preparation under refrigerated conditions for 160 days showed 58% retention in enzyme activity. The immobilized pepsin can be removed from the reaction mixture volume easily, retaining nearly 100% of its activity even after being used in seven consecutive assays.
Suggestions for the operation of radial flow cells in cell adhesion and biofouling studies
Authors: Fryer P. J. , Slater N. K. H. , Duddridge J. E. 
Published: December 2004

AbstractAn analysis of the radial flow cell is presented to show that the assumption of creeping laminar flow should be used cautiously. Simple models which account for the influence of fluid inertial forces over most of the width of the plate are reviewed. A modified Reynolds number is introduced which may be used to test the validity of the creeping flow solution.
Kinetics of cellobiose hydrolysis using cellobiase composites from Ttrichoderma reesei and Aspergillus niger
Authors: Grous William , Converse Alvin , Grethlein Hans , Lynd Lee 
Published: December 2004

AbstractThe enzymatic hydrolysis of cellulose to glucose involves the formation of cellobiose as an intermediate. It has been found necessary1 to add cellobiase from Aspergillus niger (NOVO) to the cellobiase component of Trichoderma reesei mutant Rut C‐30 (Natick) cellulase enzymes in order to obtain after 48 h complete conversion of the cellobiose formed in the enzymatic hydrolysis of biomass. This study of the cellobiase activity of these two enzyme sources was undertaken as a first step in the formation of a kinetic model for cellulose hydrolysis that can be used in process design. In order to cover the full range of cellobiose concentrations, it was necessary to develop separate kinetic parameters for high‐ and low‐concentration ranges of cellobiose for the enzymes from each organism. Competitive glucose inhibition was observed with the enzymes from both organisms. Substrate inhibition was observed only with the A. niger enzymes.
Isomaltulose production using immobilized cells
Authors: Chhetham Peter S. J. , Garrett Christine , Clark Jeremy 
Published: December 2004

AbstractThree strains of Erwinia rhapontici especially suitable for use in the form of nongrowing immobilized cells were selected by screening strains of cells for high activity and operational stability in an immobilized form. Immobilization in calcium alginate gel pellets was easily the best method of immobilizing E. rhapontici. Much greater operational stabilities were obtained than when other immobilization methods were used. Conditions of operation which optimize the activity, stability, and yield and the ease of operation of the immobilized cell columns working in a steady state are described. These include the effects of substrate concentration, diffusional restrictions and water activity, the concentration of cells immobilized, and the type of reactor used. Thus, the immobilized cells produce about 1500 times their own weight of isomaltulose during one half‐life of use (ca. 1 year). Loss of activity was most closely correlated with the volume of substrate processed and so presumably is due to the presence of low concentrations of a cummulative inhibitor in the substrate. Methods for regenerating the activity of the immobilized cells by the periodic administration of nutrients, of forming isomaltulose by continuously supplying nutrients to growing immobilized cells, and of crystallizing isomaltulose from the column eluate are also described.
Purification and characterization of endo‐xylanases from Aspergillus niger. III. An enzyme of pl 3.65
Authors: Ricardo Fournier A. , Frederick Mary M. , Frederick James R. , Reilly Peter J. 
Published: December 2004

AbstractAn endo‐xylanase (1,4‐β‐D‐xylan xylanohydrolase, EC 3.2.1.8) from Aspergillus niger was purified to homogeneity by chromatography with Ultrogel AcA 54, SP‐Sephadex C‐25 at pH 4.5, DEAE‐Sephadex A‐25 at pH 5.4, Sephadex G‐50, and DEAE‐Sephadex A‐25 at pH 5.15. The enzyme was active on soluble xylan, on insoluble xylan only after arabinosyl‐initiated branch points were removed, and on xylooligosaccharides longer than xylotetraose. There was slight activity on carboxymethyl‐cellulose, arabinogalactan, glucomannan, and p‐nitrophenyl‐β‐D‐glucopyranoside. The main products of the hydrolysis of soluble and insoluble xylan were oligosaccharides of intermediate length, especially the tri‐ and pentasaccharides. The isoelectric point of the enzyme was 3.65. It had a molecular weight of 2.8 × 104 by SDS‐gel electrophoresis, and was high in acidic amino acids but low in those containing sulfur. Highest activity in a 20‐min assay at pH 5 was between 40 and 45°C, with an activation energy up to 40°C of 11.1 kJ/mol. The optimum pH for activity was at 5.0. The enzyme was strongly activated by Ca2+.
Kinetic characterization of the extracellular xylanases of Thermomonospora sp.
Authors: Ristroph D. L. , Humphrey A. E. 
Published: December 2004

AbstractThis study deals with characterizing the extracellular xylanases produced by a strain of the thermophilic bacterial genus Thermomonospora. Supernatant from centrifuged fermentation broth was used as a crude enzyme preparation. From pH 5.5 to pH 7.7 the temperature optimum based on a 10‐min assay of activity was 80°C. The crude enzyme had a half‐life of approximately 1 month when stored at 55°C at pH 6.5. The enzyme produced a mixture of xylose oligomers from xylan, with xylobiose occuring in greatest quantity on a molar basis. Only trace quantities of xylose were produced by this hydrolysis.
Application of L‐(+)‐Lactate electrode for clinical analysis and monitoring of tissue culture medium
Authors: Tsuchida T. , Takasugi H. , Yoda K. , Takizawa K. , Kobayashi S. 
Published: December 2004

AbstractL‐(+)‐Lactate oxidase (EC 1.1.3.2) was immobilized onto the porous side of a cellulose acetate membrane with asymmetric structure which has selective permeability to hydrogen peroxide. The lactate electrode was constructed by combination of a hydrogen peroxide electrode with the immobilized enzyme membrane. Properties of the enzyme membrane and characteristics of the lactate electrode were clarified for the determination of L‐(+)‐lactic acid. The lactate electrode responded linearly to L‐(+)‐lactic acid over the final concentration 0‐0.25 mmol/L within 30 s. When the enzyme electrode was applied to the determination of L‐(+)‐lactic acid in control serum, within‐day precision (CV), analytical recovery, and correlation coefficient between the electrode method and the colorimetric method were 1.4% with a mean value of 4.54 mmol/L, 98.0%, and 0.986, respectively. The lactate electrode was sufficiently stable to perform 1040 assays over 13 days operation for the determination of L‐(+)‐lactic acid. The dried immobilized enzyme membrane retained 84% of its initial activity after storage at 4°C for 12 months. Moreover, the enzyme electrode was applied to the monitoring of culture medium for human melanoma cells. L‐(+)‐Lactate production and D‐glucose consumption were closely related to cell numbers.
Fundamental studies of glucose oxidase immobilization on controlled pore glass
Authors: Hossain Md. M. , Do D. D. 
Published: December 2004

AbstractImmobilization experiments have been performed with glucose oxidase as enzyme and controlled‐pore glass of different pore sizes as support for chemical coupling. The experimental results have been analyzed for comparison with the theoretical model predictions. Analysis of the initial stage of the process gives the fundamental characteristic of the immobilization reaction. These investigations allow us to study the influence of the degree of diffusional restriction on the evolution of the immobilization process and spatial distribution of immobilized enzyme. Nonuniformly distributed concentrations have been achieved within the porous matrix, and suggestions have been made in designing such profiles by choosing appropriate experimental parameters.
Liquid level control in an aerated continous‐flow fermentor
Authors: Anderson K. W. , Grulke E. , Gerhardt Philipp 
Published: December 2004

AbstractAn electronic liquid level control system was developed to maintain constant working volume in a continuously fed and aerated fermentor from which spent medium was continously withdrawn by microfiltration in an external recycle loop. The level control system was comprised of an admittance sensor in the fermentor and an external transmitter and controller, which together regulated the speed of a recycle pump and thus the rate of liquid withdrawal from the fermentor. During test bacterial culture the liquid level was maintained usually within ± 1% and always within ± 5%. The control system could be applied to various other types and scales of continuous‐flow fermentors.
Reaction kinetics of cephalexin synthesizing enzyme from Xanthomonas citri
Authors: Nam Doo H. , Kim Cheol , Ryu Dewey D. Y. 
Published: December 2004

AbstractIn enzymatic synthesis of cephalexin from D‐α‐phenylglycine methyl ester (PGM) and 7‐amino‐3‐deacetoxy‐cephalosporanic acid (7‐ADCA) using α‐acylamino‐β‐lactam acylhydrolase from Xanthomonas citri, it was found that this enzyme catalyzes all three reactions including PGM hydrolysis, cephalexin synthesis, and cephalexin hydrolysis. Based on our experimental results, a mechanistic kinetic model for cephalexin synthesizing enzyme system having acyl‐enzyme intermediate was proposed. From this kinetic model, the reaction rate equations for three reactions were derived, and the kinetic parameters were evaluated. A good agreement between the simulation results and the experimental results was found.
Simulation of the growth pattern of a single cell of Escherichia coli under anaerobic conditions
Authors: Ataai M. M. , Shuler M. L. 
Published: December 2004

AbstractA computer model based on a previous model for aerobic growth of Escherichia coli is described which simulates cell composition, size, and shape; length of C and D periods; cell yields; and the rate of product formation of anaerobically grown cells of E. coli B/r‐A on glucose‐limited minimal medium. To verify the simulation results, the values of cell volume, cell content of DNA, RNA, and protein, substrate yield, ATP yield, and fermentation products for various growth rates were obtained experimentally. Model predictions are in good agreement with experimental results. Such agreement supports a hypothesis that only those equations describing energy metabolism need to be modified and other cell functions are not grossly altered by a switch from aerobic to an aerobic growth. The model's ability to predict reasonable growth responses under anaerobic conditions by only modifying energy metabolism is a further indication of the robust nature of the description of cell physiology included in the development of the aerobic model.
Enzyme reactor with knitted fabric made of poly(vinyl alcohol) superfine filaments
Authors: Ichijo Hisao , Suehiro Tetsuro , Nagasawa Junichi , Yamauchi Aizo , Sagesaka Michiaki 
Published: December 2004

AbstractVarious supports and bio‐reactors have been proposed. Packed bed reactors with polymer material in granular shape are most often employed in both laboratory and industry. But they have a disadvantage related to an increase in pressure drop. We already developed filter paper composed of short cut pieces of superfine filaments (SFF). It shows high performance, but its hydrodynamic resistance increases when substrate solution passes through it. A new type of enzyme reactor equipped with knitted SFF has been proposed. In this reactor, substrate does not pass through the support but flows along the thin channel and parallel to the support. Therefore, it is able to maintain flow rate constant during a considerable period. The productivity of the reactor fairly increases by reducing the thickness of the channel because linear velocity increases with the reduction of the thickness and that contributes to the decrease in mass transfer resistance.
Effect of ultrasound treatment on the extraction of insulin
Authors: Zayas Joseph 
Published: December 2004

AbstractInsulin production requires a prolonged extraction process. An ultrasound method of insulin extraction was developed to increase efficiency. Application of ultrasound resulted in a significant increase in the extraction process as a result of pancreas tissue dispergation, destruction of the pancreas cells, intensive mixing, separation of particles, and increase in the interphase pancreas‐extractive medium. Optimal technological parameters of insulin extraction were established: ultrasound frequency, 19.5 kHz, specific intensity of ultrasound, 3.3 W/cm2; time of ultrasound exposure, 5–10 min; and influence of cavitation process. Effectiveness of insulin extraction depends on the properties of the extractive medium. Optimal conditions were pH, 1.6–1.7, concentration of alcohol, 75%, temperature of extractive mixture, 13–17°C; ratio of ground pancreas to liquid extractive medium, 1 : 3.
Induction of Cellulases in chaetomium cellulolyticum by cellobiose
Authors: Leisola Matti S. A. , Ulmer Duane C. , Pitkänen Kari , Fiechter Armin 
Published: December 2004

AbstractThe production of extracellular cellulases by Chaetomium cellulolyticum could be induced by slow feeding of cellobiose to the cultures. Both the rate of production and the amount of activity were comparable to that obtained in batch cultivation on cellulose. The specific filter paper activity of 2.06 U per mg protein was almost two times higher than that obtained in cellulose medium. Cellulases were not induced when glucose was slowly fed to the cultures. Changing the feed stream from glucose to cellobiose resulted in a rapid accumulation of cellulases. Thus cellobiose has a similar role in cellulase induction in C. cellulolyticum, as earlier shown for Trichoderma reesei.