bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of formation of maltose and isomaltose through condensation of glucose by glucoamylase
Authors: Adachi Shuji , Ueda Yasuo , Hashimoto Kenji 
Published: December 2004

AbstractA kinetic model was devised for the hydrolysis and synthesis of maltose and isomaltose by two glucoamylases from Rhizopus niveus and Aspergillus niger, and the validity of the model was verified experimentally at 313 K and pH 5.0. For both enzymes, the formations of maltose and isomaltose from glucose were parallel reversible reactions, and glucosyl transfer between maltose and isomaltose was not observed. The enzymes catalyzed rapid hydrolysis and synthesis of maltose. Isomaltose was hydrolyzed and synthesized more slowly, but the level produced from glucose was much higher than that of maltose. These hydrolysis and condensation reactions were expressed well by the model.
Equations and calculations for fermentations of butyric acid bacteria
Authors: Papoutsakis Eleftherios Terry 
Published: December 2004

AbstractA stoichiometric equation has been derived which describes the interrelations among the various products and biomass in fermentations of butyric acid bacteria. The derivation of the equation is based on an assumed ATP yield, two biological regularities, and the biochemistry of product formation of the fermentations. The equation obeys the constraints imposed on growth and product formation by thermodynamics and the biochemical topology. The validity of the equation is tested using a variety of fermentation data from the literature. The uses, improvements, limitations, and extensions of the equation are also discussed in detail. For example, the fermentation equation is used to calculate the maximal possible yields of the main fermentation products.
The growth of Saccharomyces cerevisiae CBS 426 on mixtures of glucose and succinic acid: A model
Authors: Bonnet J. A. B. A. F. , Koellmann C. J. W. , Dekkers‐de Kok Hermine E. , Roels J. A. 
Published: December 2004

AbstractSaccharomyces cerevisiae CBS 426 was grown in continuous culture in a defined medium with a mixture of glucose and succinic acid as the carbon source. Growth on succinic acid was possible after long adaptation periods. The flows of glucose, succinic acid, oxygen, carbon dioxide, and biomass to and from the system were measured. It proved necessary to expand our previous model to accommodate the active transport of succinic acid by the cell. The values found for the efficiency of the oxidative phosphorylation (P/O) and the amount of ATP needed for production of biomass from monomers gave the same values as found for substrate mixtures taken up passively.
Purification and some properties of pure Cochliobolus lunatus fibrinolytic Enzyme
Authors: Abdel‐Fattah Ahmed F. , Ismail Abdel‐Mohsen S. 
Published: December 2004

AbstractPurification of partially purified fibrinolytic enzyme was attempted by chromatography on DEAE‐cellulose (D‐52) column. The results indicated the resolution of three protein components and one minor component. It was shown that the first component was the major of the applied sample. Examination of fibrinolytic activity of the different fractions of components one and two indicated that only the first component possessed fibrinolytic activity. Fibrinolytic activity of the applied sample was completely recovered by the first enzyme component, and the most active fraction of this enzyme component showed 3.3‐fold purification. The pure fibrinolytic enzyme was relatively more stable at pH 6.98, which was also optimal for its activity. After heating the enzyme solution (pH = 6.98) at 55 and 60°C for 15 min, the enzyme still retained 34.7 and 17.3% of its original activity, respectively. Zinc ions partially inhibited the enzyme. Copper ions activated the enzyme. Iodine partially inhibited the fungal fibrinolytic enzyme at a final concentration of 10−4M; at 10−2M complete inactivation was brought about. The p‐chloromercuribenzoate at a final concentration of 10−2M brought about partial inhibition whereby the enzyme lost about 33% of its original activity. Reduced glutathione brought about activation of the enzyme, while trypsin inhibitor did not show any effect on enzyme activity.
Competitive adsorption of cellulase components and its significance in a synergistic mechanism
Authors: Ryu Dewey D. Y. , Kim Cheol , Mandels M. 
Published: December 2004

AbstractSome studies on the adsorption of cellulase on cellulose revealed part of the mechanisms involved in the enzymatic hydrolysis of cellulose and provided some clues to the synergistic mechanism of cellulase complex. The adsorption of cellulase was significantly affected by the reaction conditions and physical chemical characteristics of cellulose. Endoglucanase consisted of adsorbable and nonadsorbable components. Cellobiohydrolase had the strongest adsorption affinity. Each cellulase component is postulated to have distinctly different adsorption sites on cellulose, corresponding to the active sites in the hydrolysis reaction. Competitive adsorption kinetics between cellulase components were also observed during the adsorption process. The degree of competitive adsorption was most remarkable when the composition of cellulase components was nearly the same as that in the crude cellulase complex. This seems to show the optimal relative composition of cellulase components. The synergism between cellobiohydrolase and endoglucananse could be elucidated more clearly by this competitive adsorption model of the reaction mechanism.
Acid phosphatase deactivation by a series mechanism
Authors: Gianfreda Liliana , Marrucci Giuseppe , Grizzuti Nino , Greco Guido 
Published: December 2004

AbstractAcid phosphatase (E.C.3.1.3.2.) thermal deactivation at pH 3.77 has been investigated by monitoring the enzyme activity as a function of time in the hydrolysis of p‐nitrophenyl phosphate. The experimental curves obtained show a two‐slope behavior in a log (activity)versus‐time plot, which indicates that deactivation occurs via a complex mechanism. From the dependence of the kinetic parameters on both deactivation and hydrolysis temperatures, it is inferred that the deactivation mechanism involves intermediate, temperature‐dependent, less‐active forms of the enzyme. This interpretation is confirmed by the results of additional tests in which the temperature was suddenly changed during the deactivation process.
The construction and operation of a low‐cost poultry waste digester
Authors: Steinsberger Scott C. , Shih Jason C. H. 
Published: December 2004

AbstractA simple and low‐cost poultry waste digester (PWD) was constructed to treat the waste from 4000 caged laying hens on University Research Unit No. 2 at North Carolina State University. The system was built basically of a plastic lining with insulation, a heating system, a hot‐water tank, and other metering equipment. It was operated at 50°C and pH 7.5–8.0. The initiation of methane production was achieved using the indigenous microflora in the poultry waste. At an optimal loading rate (7.5 kg volatile solids/m3 day), the PWD produced biogas (55% methane) at a rate of 4.0 m3/m3 day. The PWD was biologically stable and able to tolerate temporary overloads and shutdowns. A higher loading rate failed to maintain a high gas production rate and caused drops in methane content and pH value. Under optimal conditions, a positive energy balance was demonstrated with a net surplus of 50.6% of the gross energy. For methane production, the PWD system was proved to be technically feasible. The simple design and inexpensive materials used for this model could significantly reduce the cost of digestion compared to more conventional systems. More studies are needed to determine the durability, the required maintenance of the system, and the most economical method of biogas and solid residue utilization.
Oxidative assimilation treatment of a nitrogen‐deficient toxic waste
Authors: Rozich A. F. , Lowe W. L. 
Published: December 2004

AbstractBatch growth tests were performed under both replicating and nonproliferating (no nitrogen source in medium) conditions with acclimated heterogenous populations that utilized phenol as a sole source of carbon and energy. It was shown that the acclimated populations could efficiently remove the toxic waste component phenol under nonproliferating conditions by utilizing an oxidative assimilation mechanism. The phenol was assimilated and converted into nonnitrogenous storage products. During the assimilation process, the cells had a tendency to excrete some product (nonsubstrate) chemical oxygen demand (COD). Bench‐scale oxidative assimilation units were operated by sequentially feeding a carbon source (phenol) and nitrogen source (ammonium sulfate) to heterogeneous populations. This demonstrated that, subsequent to the addition of the nitrogen source to the medium, the cells utilized the stored carbon for replication. Four of these units were operated at different phenol COD‐to‐ammonia‐nitrogen ratios of 10:1, 20:1, 40:1, and 50:1. All of these units demonstrated excellent removal of phenol using an oxidative assimilation mechanism. These results suggested the feasibility of utilizing a continuous flow oxidative assimilation process for the treatment of nitrogen‐deficient phenolic wastes. This process would be advantageous over conventional treatment processes in that it would realize a savings in chemical costs (ammonia as nitrogen source) and prevent leakage of excess ammonia from the system.
Study of models of single populations: Development of equations used in microorganism cultures
Authors: Qiwu Cui , Lawson G. J. , Deen Gao 
Published: December 2004

AbstractThis article derives a number of equations which can be used in both continuous and the semicontinuous cultures of microorganism populations in chemostat systems. Using these equations, some phenomena which have been known for many years can be explained reasonably in terms of chemical kinetics, and a number of analytical solutions can be obtained instead of numerical solutions previously published.
An enzyme coimmobilized with a microorganism: The conversion of cellobiose to ethanol using β‐glucosidase and Saccharomyces cerevisiae in calcium alginate gels
Authors: Hahn‐Hägerdal Bärbel 
Published: December 2004

AbstractThe efficiency of β‐glucosidase and Saccharomyces cerevisiae in directly converting cellobiose to ethanol was studied for various combinations of the two catalytic species, both free and immobilized, in order to elucidate the advantages of using a coimmobilized system. The coimmobilized preparation was superior to a combination of separately immobilized biocatalysts. However, in this preparation, one‐half the enzyme activity was lost within a week when incubated at the operational temperature in the absence of substrate. In continuous experiments, an 80% conversion of cellobiose to ethanol was obtained using the coimmobilized preparation, compared to 40% using separately immobilized biocatalysts when applying a dilution rate of 0.1 h−1 in a packedbed reactor. The immobilized biocatalysts showed no decline in productivity during two weeks of continuous operation.
Microbial validation of vent filters
Authors: Robertson John H. , Frieben W. R. 
Published: December 2004

AbstractThe Upjohn Company uses filtration to remove microorganisms and particulates from air and other gases which may come in contact with sterile products. To validate the microbial retentivity of these filters, they were challenged with an aerosol of Bacillus subtilis var niger spores. An aerosol challenge was used because it more closely simulated the use for which these filters were designed. The test apparatus was constructed of autoclavable components using a jet‐type nebulizer and heated air mixing tube. Characterization of the aerosol particle size distribution with a particle size analyzer demonstrated that 80% of the particles had a diameter of × 3.0 times;m and that the particles had a mean mass diameter of 1.9 times;m with a geometric standard deviation of 1.8 times;m. Studies conducted with aerosols of Bacillus subtilis var niger spores demonstrated that the test apparatus could recover ca. 50% of the spores that were aerosolized. Hydrophobic filters from various manufactures were challenged with an aerosol of at least 108 spores of Bacillus subtilis. All filters tested could retain at least 109 spores when physical integrity of the filter was verfield.
Electrochemical and enzymatic activity of flavin adenine dinucleotide and glucose oxidase immobilized by adsorption on carbon
Authors: Miyawaki Osato , Wingard Lemuel B. 
Published: December 2004

AbstractFlavin adenine dinucleotide (FAD) and glucose oxidase were adsorbed on medium porosity spectroscopic graphite (SG) and on low porosity glassy carbon (GC) with retention of electrochemical activity, as measured by cyclic and differential pulse voltammetry. Adsorption on the SG was very strong, while that on GC was much weaker. Enzyme activity could be partially restored by the addition of the apoenzyme of glucose oxidase to the SG‐adsorbed FAD preparation. The holoenzyme of glucose oxidase also was adsorbed on SG with retention of enzyme activity. The mechanism for the reconstitution of active enzyme from adsorbed FAD and soluble apoenzyme is not clear. The data suggest that the reconstituted enzyme stays adsorbed to the SG, but it is not clear whether the FAD or protein portions (or both) are adsorbed after reconstitution. The data also indicate that substrate mass transfer resistance may be important with the reconstituted–adsorbed enzyme.
Genetically structured models for lac promoter–operator function in the chromosome and in multicopy plasmids: Lac promoter function
Authors: Lee Sun Bok , Bailey James E. 
Published: December 2004

AbstractA mathematical model based on molecular mechanisms for regulation of the lactose (lac) operon in Escherichia coli has been extended and applied to investigate the lac promoter function in the chromosome and in multicopy plasmids. The model simulates the influence of certain host cell mutations and also mutations in the lac promoter sequence in the chromosome in reasonable agreement with previous experimental measurements. The effect of the plasmid copy number and the cloning vector size on the promoter function of a cloned lac regulatory sequence in multicopy plasmids has also been examined. Model results indicate that the efficiency of the cloned lac promoter function is significantly decreased as the number of promoters per cloning vector and size of the vector are increased. The simulation results predict a maximum in the cloned gene transcription rate with respect to the plasmid copy number.
Two‐phase anaerobic fermentation of liquid swine waste to methane
Authors: Cseh Tibor , Czakó Lajos , Czakó Jenö , Tengerdy Robert P. 
Published: December 2004

AbstractTwo‐phase anaerobic digestion of liquid swine manure has been developed with options for single‐cell protein (SCP) or methane production. In the acidogenic phase at two to four days retention time, and 2.5–7.0% dry matter (DM) concentration, 8–46% of the volatile solids was solubilized. Maximum reactor capacity was 3.86 g/L at 7.0% DM concentration, but optimal operation was achieved at 4.5% DM concentration at four days retention time. The second methanogenic phase was operated continuously and had a maximum specific methane production rate of 0.70 L/L day at 12 days retention time. With recirculation, the rate was 1.16 L/L day at 8.5 days retention time with 52.7% conversion of organic matter. Maximum digestibility was 66% of the lignin free organic matter.
Biological denitrification in a fluidized bed
Authors: Narjari N. K. , Khilar Kartick C. , Mahajan S. P. 
Published: December 2004

AbstractA fluidized bed biofilm reactor using sand as the carrier particle was employed to study the effects of superficial velocity on the removal of nitrates as well as on the growth of the biofilm. Velocity was found to affect significantly both nitrate removal and biofilm growth. An analysis based on heterogenous catalysis was used to describe the denitrification process. There is good agreement between analysis and experimental measurements for startup and steady‐state operating conditions.
Kinetics of enzymatic starch liquefaction: Simulation of the high‐molecular‐weight product distribution
Authors: Rollings James E. , Thompson Robert W. 
Published: December 2004

AbstractEnzymatic corn starch liquefaction with α‐amylase was carried out. Molecular weight distributions of the resulting hydrolysates are presented using aqueous size exclusion chromatographic techniques. It is demonstrated that despite the fact that the enzyme employed reacts in a random endoacting manner, the product distributions are nonrandom. The results are explained in part by a multimerization process whereby the polymeric substrate molecules preferentially associate, forming intermolecular aggregates. These aggregates are either a consequence of the manner in which the material is deposited into the native granular structure of starch or due to intrinsic physical chemical properties of the polysaccharide. In the latter case, the results are shown to correspond to known multimerized amylose, although complete characterization of the polysaccharide is currently not available. The results presented are used to develop a simplified kinetic model of starch liquefaction and shown to simulate the product distributions accurately.
Kinetic study of instability of recombinant plasmid pPLc23trpAl in E. coli using two‐stage continuous culture system
Authors: Siegel R. , Ryu Dewey D. Y. 
Published: December 2004

AbstractDerepression of the phage λ pL promoter on recombinant plasmid pPLc 23‐trpAl caused a rapid increase of plasmid free segregants in the population. In continuous culture, increased production of trpA protein follwing derepression was accompanied by a continuous deceleration of specific growth rate. In the repressed condition, plasmid loss per generation in continuous culture decreased as dilution rate increased from 0.06 to 1.08 h−1. Over this range, the concentration of plasmid DNA within the cell decreased eightfold corresponding to a decrease in plasmid number from 74 to 32 molecules/cell. The use of a two‐stage continuous culture system coupled with a temperature sensitive expression system allows a high trpA productivity from the derepressed plasmid for more than 48 h and also offers a possibility of minimizing the instability problem of high expression recombinants. Such a system also permits the critical study of the effects of fermentation and other regulatory parameters on expression under better controlled conditions than is possible in a batch culture or single‐stage continous culture.
Isolation and partial characterization of a mutant of Penicillium funiculosum for the saccharification of straw
Authors: Hoffman R. M. , Wood T. M. 
Published: December 2004

AbstractClearing of agar plates containing ball‐milled, delignified straw has been used for screening mutants of Penicillium funiculosum IMI 87160 iii. The effects of glycerol and a number of sugars on the clearing were investigated for selecting derepressed mutants. The β‐glucosidase synthesis by one such mutant, C22c, in shake flasks containing straw was not repressed by 5% glycerol, whereas activities on filter paper, CM‐cellulose, and p‐nitrophenyl‐β‐xylosidase were only partially derepressed; xylanase was extensively derepressed. The evidence for separate control of the enzymes involved in the solubilization of straw is discussed.
Hydroxylation of biphenyl by Aspergillus parasiticus: Approaches to yield improvment in fermenter cultures
Authors: Cox John C. , Golbeck John H. 
Published: December 2004

AbstractWe carried out experiments designed to increase the rate of production of 4,4′‐dihydroxybiphenyl (biphenol) from biphenyl by Aspergillus parasiticus. We show that 0.5 mg/ml biphenyl, the substrate for the reaction, significantly inhibits growth of the organism and that at 0.04 mg/ml, 2‐hydroxybiphenyl or 4‐hydroxybiphenyl (an intermediate of the reaction) strongly inhibit oxygen uptake, probably by inhibition of mitochondrial electron transport. Both factors may contribute to the low hydroxylation rates observed previously [J. H. Golbeck and J. C. Cox, Biotechnol. Bioeng., 26, 434 (1984)]. We therefore adapted the organism to the presence of 0.08 mg/ml 2‐ and 4‐hydroxybiphenyl in the growth medium and found that cultures of adapted strains hydroxylated biphenyl at rates ca. three‐fold faster than control cultures. Once the fungal mycelia were grown, they could be recycled at least twice into fresh fermentation broth. Recycled organisms were capable of hydroxylating biphenyl more rapidly than cells in the primary fermentation culture and there was no lag period between introduction of biphenyl and the onset of hydroxylation. Cell recycle thus results in a considerable saving in carbon costs and fermentation time.
Effect of hydrogen peroxide pretreatment on the structural features and the enzymatic hydrolysis of rice straw
Authors: Wei Chia‐Jenn , Cheng Chung‐Yueh 
Published: December 2004

AbstractAssessment was made to evaluate the effect of hydrogen peroxide pretreatment on the change of the structural features and the enzymatic hydrolysis of rice straw. Changes in the lignin content, weight loss, accessibility for Cadoxen, water holding capacity, and crystallinity of straw were measured during pretreatment to express the modification of the lignocellulosic structure of straw. The rates and the extents of enzymatic hydrolysis, cellulase adsorption, and cellobiose accumulation in the initial stage of hydrolysis were determined to study the pretreatment effect on hydrolysis. Pretreatment at 60°C for 5 h in a solution with 1% (w/w) H2O2 and NaOH resulted in 60% delignification, 40% weight loss, a fivefold increase in the accessibility for Cadoxen, an one times increase in the water‐holding capacity, and only a slight decrease in crystallinity as compared with that of the untreated straw. Improvement on the pretreatment effect could be made by increasing the initial alkalinity and the pretreatment temperature of hydrogen peroxide solution. A saturated improvement on the structural features was found when the weight ratio of hydrogen peroxide to straw was above 0.25 g H2O2/g straw in an alkaline H2O2 solution with 1% (w/w) NaOH at 32°C. The initial rates and extents of hydrolysis, cellulase adsorption, and cellobiose accumulation in hydrolysis were enhanced in accordance with the improved structural features of straw pretreated. A four times increase in the extent of the enzymatic hydrolysis of straw for 24 h was attributed to the alkaline hydrogen peroxide pretreatment.
Cellulase production by a solid state culture system
Authors: Kim Jung Hoe , Hosobuchi Masahiko , Kishimoto Michimasa , Seki Tatsuji , Yoshida Toshiomi , Taguchi Hisaharu , Ryu Dewey D. Y. 
Published: December 2004

AbstractProduction of cellulase using solid culture systems of Trichoderma reesei QM9414 and Sporotrichum cellulophilum on wheat bran was studied. By using moisture‐controlled solid culture equipment, the effect of water content of wheat bran on cell growth and cellulase production was investigated. Cellular biomass grown on solid substrate was estimated by measuring oxygen consumption rate and glucosamine content of the cells. These parameters were shown to have a good linear correlation with the specific growth rate. This reliable method of estimating the cell growth rate enabled us to simulate the enzyme production in a solid culture system by means of multiple linear regression analysis which takes into account of the water content, cell mass, and the oxygen consumption rate as variables. The cell growth and cellulase production were maximized at different water content of the medium. A high water content, 57% for T. reesei and 70% for S. cellulophilum, favored mycelial growth, while the maximum cellulase activity was obtained at a lower water content such as 50% for both fungi. It was observed that cellulase production by T. reesei depended on the culture conditions that support the optimal growth rate for the maximum enzyme production.