bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical and gamma‐ray‐modified bagasse as substrates for bioproduction of cellulases and protein
Authors: Lillehoj E. B. , Han Y. W. 
Published: December 2004

AbstractProduction of enzymes in the cellulolytic complex was determined in culture filtrates of six fungal isolates grown on chemically treated or gamma‐irradiated bagasse. The enzymatic activities of the filtrates were determined by measurement of glucose release from cotton, filter paper, carboxymethylcellulose, cellobiose, and cellobiose octaacetate. Cultures grown on base‐treated and gamma‐irradiated plus acid‐treated bagasse provided culture filtrates with the highest enzymatic activities whereas α‐cellulose, untreated, and acid‐treated bagasse were the poorest substrates for enzyme production. Filtrates of Trichoderma reesei QM 9414 yielded the highest cellulolytic activity in all test media. The largest accumulation of fungal‐derived, extracellular protein was observed in media containing gamma‐irradiated bagasse as the carbon substrate.
A simple algal production system designed to utilize the flashing light effect
Authors: Laws E. A. , Terry K. L. , Wickman J. , Chalup M. S. 
Published: December 2004

AbstractArrays of foils similar in design to airplane wings have been placed in an algal culture flume to create systematic mixing. Vortices are produced in the culture due to the pressure differential created as water flows over and under the foils. In a flume having a flow rate of 30 cm/s, the foil arrays produced vortices with rotation rates of ca. 0.5−1.0 Hz. This rotation rate is satisfactory to take advantage of the flashing light effect if the culture is sufficiently dense. Solar energy conversion efficiencies in an experimental culture of P. tricornutum increased 2.2–2.4 fold with the foil arrays in place versus controls with no foil arrays and solar energy conversion efficiencies averaged 3.7% over a three‐month period. Five‐day running means of solar energy conversion efficiencies reached as high as 10% during the three‐month period. The use of foil arrays appears to be an effective and inexpensive way to utilize the flashing light effect in a dense algal culture system.
Productions of cellulase from Pestalotiopsis versicolor
Authors: Rao M. N. A. , Mithal B. M. , Thakur R. N. , Sastry K. S. M. 
Published: December 2004

AbstractProduction of cellulase from Pestalotiopsis versicolor was studied in a shake flask culture. The cellulase system was found to be rich in β‐glucosidase. Kinetic parameters such as pH and temperature have been optimized for the various enzyme components.
Automatic on‐line fermentation headspace gas analysis using a computer‐controlled gas chromatograph
Authors: Comberbach D. Martin , Bu'lock John D. 
Published: December 2004

AbstractA computer‐controlled headspace gas chromatograph was used to monitor the progress of ethanol production from both aerobic batch and anaerobic continuous fermentations. Using an automatic, electropneumatic sampling system, aliquots of fermentation headspace gas were injected directly onto the column for quantitative ethanol determinations every six minutes. A sample volume of 1 mL permitted liquid ethanol concentrations from 2 to 100 g/L to be measured with better than 3% standard deviation on five repeated injections. Provided fermenter liquid temperature and ionic strength were maintained constant, the signal‐tohyphen;concentration ratio remained linear to 80 g/L ethanol. This quantitative gas chromatographic (GC) method is suitable for accurate, precise analysis of multiple solvent fermentations, and is limited only by the elution rate and separating capacity of the GC column.
Mathematical description of anaerobic treatment of wastewater in upflow reactors
Authors: Van Der Meer R. R. , Heertjes P. M. 
Published: December 2004

AbstractA quantitative description has been presented of anaerobic treatment in an upflow reactor of dilute wastewater containing lower fatty acids as the main pollutant. It contains as its principal elements mathematical descriptions of the dynamic behavior and the distribution of both the fluid and the anaerobic sludge in the reactor, and a quantification of the kinetics of the anaerobic conversion of the organic waste and of the formation of bacterial products and methane. These elements have been taken together in mass (organic carbon) balances for the substrate, the methane, and the bacterial products, over the two most important reactor parts: the sludge bed and the sludge blanket. In the second part of this article, the description has been used for prediction and determination of the optimum reactor dimensions and process conditions. These optimum values can be used for the design of new reactors and for the establishment of the best suited process operation, which is important for obtaining the best purification results and process reliability at minimum investment and operation costs.
Factors effecting cell attachment, spreading, and growth on derivatized microcarriers: II introduction of hydrophobic elements
Authors: Reuveny Shaul , Mizrahi Avshalom , Kotler Moshe , Freeman Amihay 
Published: December 2004

AbstractIn a previous publication, the authors described the establishment of a working system for studing effects of factors involved in the chemical nature of a microcarrier on cell attachment, spreading, and growth. The first part of the rsearch dealt with the influence of the type and amount of the positively charged groups. In the present article, the authors will describe the effect of the introduction of hydrophobic elements onto primary amino derivatized polyacrylamide microcariers. It was found that cell attachement kinetics were gradually enhanced in parallel to a gradual increase in hydrophobicity via elongation of the hydrocarbon side‐chain carrying the primary amino charged group. A threshold effect of the amount of charge required for cell attachment spreading and growth was exhibited on all the tested primary amino derivatized microcarriers. Optimum cell growth was recorded for the butylamine and hexylamine polyacrylamide microcarris. Lowre cell yields were recorded for ethylamine and octylamine derivatives. The location of the introduced hydrophobic element has a profound effect on cell propagation. Introduction of hydrophobicity onto the polymeric backbone of the microcarrier (via copolymerization of hydrophobic comonomer) lead to negative influence on cell attachement and growth yields. Out of the series of derivatized polyacrylamide microcarriers tested, it seems that the hexylamine derivative may be a potential alternative for the commonly used tertiary amine microcariers.
Isoelectric precipitation of soy protein: I. Factors affecting particle size distribution
Authors: Petenate Angela M. , Glatz Charles E. 
Published: December 2004

AbstractThe particle size distribution (PSD) of soyabean protein aggregates obtained by acid precipitation in a continuous stirred reactor was measured with a Coulter Counter model TA II. Effects of changes in the operating variables pH, concentration, mean residence time, power input, and ionic strength were investigated. Power input affects both growth and breakup while pH and ionic strength seem to exert their influence through solubility and aggregate strength. Changes in ζ‐potential can explain most of these observations.
Effect of air supplement on the performance of continuous ethanol fermentation system
Authors: Ryu Dewey D. Y. , Kim Y. J. , Kim J. H. 
Published: December 2004

AbstractFor the purpose of improving ethanol productivity, the effect of air supplement on the performance of continuous ethanol fermentation system was studied. The effect of oxygen supplement on yeast concentration, cell yield, cell viability, extracellular ethanol concentration, ethanol yield, maintenance coefficient, specific rates of glucose assimilation, ethanol production, and ethanol productivity have been evaluated, using a high alcohol tolerant Saccharomyces cerevisiae STV89 strain and employing a continuous fermentor equipped with an accurate air metering system in the flow rate range 0–11 mL air/L/h. It was found that, when a small amount of oxygen up to about 80μ mol oxygen/L/h was supplied, the ethanol productivity was significantly enhanced as compared to the productivity of the culture without any air supplement. It was also found that the oxygen supplement improved cell viability considerably as well as the ethanol tolerance level of yeast. As the air supply rate was increased, from 0 to 11 mL air/L/h while maintaining a constant dilution rate at about 0.06 h−1, the cell concentration increased from 2.3 to 8.2 g/L and the ethanol productivity increased from 1.7 to 4.1 g ethanol/L/h, although the specific ethanol production rate decreased slightly from 0.75 to 0.5 g ethanol/g cell/h. The ethanol yield was slightly improved also with an increase in air supply rate, from about 0.37 to 0.45 ethanol/g glucose. The maintenance coefficient increased by only a small amount with the air supplement. This kind of air supplement technique may very well prove to be of practical importance to a development of a highly productive ethanol fermentation process system especially as a combined system with a high density cell culture technique.
A rapid and simplified procedure for purification of a cellulase from Fusarium lini
Authors: Vaidya Madhavi , Seeta R. , Mishra Chittra , Deshpande Vasanti , Rao Mala 
Published: December 2004

AbstractAn endo‐β‐1,4‐glucanase (EC 3.2.1.4) was obtained in high yields in purified form a culture filtrate of Fusarium lini by an extremely simple method. The method consists of precipitation of the culture filtrate with ammonium sulphate (290 g/L), followed by chromatography of the precipitated fraction on Biogel P‐150. The purification is based on the unusual property of the enzyme being eluted after cytochrome C, even though it molecular weight is 2.8 × 104 (by SDS PAGE). The yield of pure enzyme was 6.8 mg/L culture broth. The homogeneity of the enzyme was established by ultracentrifugation, isoelectric focusing, and electrophoresis in polyacrylamide gels containing SDS. The enzyme was isoelectric at pH 8.3 and contained 2.9% carbohydrate. The Km value for carboxymethyl (CM) cellulose was 11.6 mg/mL. The enzyme showed high viscosity reducing activity towards CM cellulose but very low activity with Walseth cellulose and crystalline celluloses such as Avicel and cotton. The purified enzyme has activity towards xylan. The amino acid analysis showed a predominance of acidic and neutral amino acids and low contents of histidine, arginine, and methionine. One‐half of the cysteine content was 11 residues/mol enzyme, and no free–SH group was detectable.
Diffusion characteristics of substrates in Ca‐alginate gel beads
Authors: Tanaka Hideo , Matsumura Masatoshi , Veliky I. A. 
Published: December 2004

AbstractThe diffusion characteristics of several substrates of varying molecular sizes into and from Ca‐alginate gel beads in well‐stirred solutions were investigated. The values of the diffusion coefficient (D) of substrates such as glucose, L‐tryptophan, and α‐lactoalbumin [with molecular weight (MW) less than 2 × 104] into and from the gel beads agreed with those in the water system. Their substrates could diffuse freely into and from the gel beads without disturbance by the pores in the gel beads. The diffusion of their substrates into and from the gel beads was also not disturbed by increasing the Ca‐alginate concentration in the beads and the CaCl2 concentration used in the gel preparation. In the case of higher molecular weight substances such as albumin (MW = 6.9 × 104), γ‐globulin (MW = 1.54 × 105) and fibrinogen (MW = 3.41 × 105), the diffusion behaviors of the substrates into and from the gel beads were very different. No diffusion of their substrates into the gel beads from solutions was observed, and only albumin was partly absorbed on the surface of the gel beads. The values of D of their substrates from the gel beads into their solutions were smaller than their values in the water system, but all their substrates could diffuse from the gel beads. The diffusion of high molecular weight substrates was limited more strongly by the increase of Ca‐alginate concentration in the gel beads than by the increase of the CaCl2 concentration used in the gel preparation. Using these results, the capacity of Ca‐alginate gel as a matrix of immobilization was discussed.
Effect of dissolved oxygen on nitrogen fixation by A. vinelandii. II. Ionically adsorbed cells
Authors: DiLuccio Robert C. , Kirwan Donald J. 
Published: December 2004

AbstractContinuous culture studies of Azotobacter vinelandii cells immobilized by ionic adsorption to Cellex E anion exchange resin were conducted under oxygen‐limited conditions for comparison to free‐cell cultures. Immobilization had little effect upon the specific respiration and sucrose consumption rates as compared to free cells. However, maxima in specific nitrogen fixation rate and nitrogenase activity as a function of dissolved oxygen occurred at a C value of approximately 0.005 mM as opposed to 0.02 mM for free cells. Further, in contrast to free‐cell culture, most of the fixed nitrogen appeared in the medium rather than within intact cells. There were strong indications that reproduction of bound cells often resulted in cell lysis accounting for the fixed nitrogen content in solution.
Continuous bacterial coal desulfurization employing Thiobacillus ferrooxidans
Authors: Myerson Allan S. , Kline Paul C. 
Published: December 2004

AbstractThe leaching of pyrite sulfur from coal employing Thiobacillus Ferrooxidans was studied in a continuous stirred tank reactor at a variety of dilution rates (0.02–0.11 h−1) and coal surface areas (0.25–1.0 m2/mL). The bacterial leaching rate was found to increase with increasing coal surface area concentration and increasing dilution rate. The bacterial concentration on the coal surface was related to the bacterial concentration in solution by a irreversible second‐order (of the second kind) kinetic equation. The concentration of bacteria on the coal in all experiments was the concentration at saturation. Step changes in the coal concentration were observed to result in dramatic declines in bacterial concentration in solution. A bacterial mass balance model was employed to calculate the specific growth rate on the solid which was observed to increase with increasing dilution rate.
Immobilized cell cross‐flow reactor
Authors: Chotani G. K. , Constantinides A. 
Published: December 2004

AbstractA cross‐current flow reactor was operated using sodium alginate gel entrapped yeast cells under growth conditions. Micron‐sized silica, incorporated into the biocatalyst particles (1 mm mean diameter) improved mechanical strength and internal surface adhesion. The process showed decreased productivity and stability at 35°C compared to the normal study done at 30°C. The increased number of cross flows diminish the product inhibition effect. The residence time distribution shows that the cross‐flow bioreactor system can be approximated to either a train of backmixed fermentors in series or a plug flow fermentor with moderate axial dispersion.
Application of immobilized invertase to continuous hydrolysis of concentrated sucrose solutions
Authors: Monsan P. , Combes D. 
Published: December 2004

AbstractInvertase immobilized onto corn grits was utilized in the hydrolysis of highly concentrated sucrose solutions producting liquid sugar solutions containing glucose and fructose. Comparisons of conversion efficiencies of this immobilized invertase in a continuous stirredtank reactor and a plug‐flow reactor indicated that the plug‐flow reactor has an higher efficiency. Continuous sucrose hydrolysis was then performed in 0.1‐ and 1‐L tubular reactors. This tenforld scaling‐up was achieved without any noticeable loss in efficiency. This process thus was scaled‐up to a 17.6‐L pilot reactor set in a cane sugar refinery. This reactor was fed with highly concentrated sucrose solutions [71% (w/w)] to produce invert sugar syrup with the desired inversion degree. It allows a productivity equal to 9.1 kg sucrose hydrolyzed/h in the case of a 69% (w/w) sucrose initial concentration with a 72% conversion rate.
Instability kinetics of trp operon plasmid ColEl‐trp in recombinant Escherichia coli MV 12[pVH5] and MV 12trp R [pVH5]
Authors: Kim Sung H. , Ryu Dewey D. Y. 
Published: December 2004

AbstractIn studying plasmid instability in recombinant microorganisms, Escherichia coli MV 12[p VH5] and MV 12 trpR[p VH5] harboring trp operon were used as experimental model systems. The host with the trp repression system was partially derepressed by 3‐beta‐indoleacrylic acid. The results from kinetic analysis of plasmid instability showed that the stability of p VH5 and the growth rate of MV 12[p VH5] decreased rapidly in presence of 3‐beta‐indoleacrylic acid at a concentration higher than 10 μg/mL, but beyond 30 g/mL no significant change was observed. This suggests that Trp− variants from MV 12[p VH5] could be produced from the host cells at a different frequency depending on the physiological condition. In another system, MV 12 trpR[p VH5] which was constructed by conjugation of E. coli MV 12[p VH5] with E. coli CSH61, the plasmid stability was much lower and the frequency of Trp− cell production was about 10 times higher as compared with the MV 12[p VH5] when treated with 3‐beta‐indoleacrylic acid. A kinetic model representing the plasmid instability was derived, and a fairly good agreement with the experimental results was found. The fraction of plasmid‐free cell (or negative variant) shows a different time course profile depending on the segregation coefficient (a, production rate of negative variants from positive cells during one generation), growth ratio (G, the ratio of growth rates of negative variants to positive cells), and other parameters. The negative variant fraction continues to increase (“run away” type) or it approaches to a finite value (“settling” type) depending on the relative values of a and G.
Streptomyces flavogriseus cellulase: Evaluation under various hydrolysis conditions
Authors: MacKenzie C. R. , Bilous D. , Johnson K. G. 
Published: December 2004

AbstractStreptomyces flavogriseus CMCase and Avicelase were very stable at 30°C but not at 40°C or higher. β‐Glucosidase was less stable at all temperatures tested. Stabilities were similar at pH values between 5.5 and 7, the optimal range for enzyme activity. Cellulose solubilizing activity was reduced by 40% at a cellobiose concentration of 150mM but glucose inhibited activity by only 10% at this concentration. β‐Glucosidase was inhibited by 40% at a glucose concentration of 10mM (ten times the substrate concentration). Relatively dilute S. flavogriseus cellulase extensively hydrolysed acid‐swollen cellulose at concentrations as high as 10%. More highly crystalline forms of cellulose were more resistant to attack.
A finite representation model for an asynchronous culture of E. coli
Authors: Domach M. M. , Shuler M. L. 
Published: December 2004

AbstractA computer model is described which models an asynchronous population of E. coli by using a large, but finite number of representative single cells. Asynchrony generation and maintenance occurs at the single cell level by modulating the activity of an enzyme responsible for septum formation. Such modulation introduces cycle time imprecision and does not require the introduction of any new parameters into the single‐cell model. Based on comparisons to experiment, reasonable predictions are possible for changes of cellular dry weight during exponential growth and turbidostat washout, and overall chemostat cell yields and changes in cell number, glucose concentration, and cell size distribution for a chemostat subject to a step change in dilution rate. Additionally, a correlation between cell RNA content and size is predicted as is an inertial effect when chemostat residence time is decreased under conditions of initially high glucose concentrations. Limitations imposed by the model's finite nature and their solutions are discussed.
The estimation of growth yield and maintenance parameters for photoautotrophic growth
Authors: Lee H. Y. , Erickson L. E. , Yang S. S. 
Published: December 2004

AbstractMethods are presented for examining the consistency of experimental data for microbial growth where light energy is converted to chemical energy through photosynthesis. True growth yield and maintenance parameters are estimated for several sets of available experimental data. Methods of parameter estimation are presented which allow all of the measured variables to be used simultaneously for parameter estimation. The results show that a wide range of values have been found for the true growth yield and maintenance parameters. Values of the true growth yield range from 0.04 to values above those predicted by the Z‐scheme model for photosynthesis.
Production of ethyl acetate from dilute ethanol solutions by Candida utilis
Authors: Armstrong David W. , Martin Stanley M. , Yamazaki Hiroshi 
Published: December 2004

AbstractThe conversion of ethanol to ethyl acetate has an advantage as a method of ethanol recovery since ethyl acetate is amenable to simple solvent extraction. The potential of Candida utilis in this conversion was studied. The kinetics of accumulation of ethanol and ethyl acetate in glucose‐grown C. utilis showed that ester formation resulted from ethanol utilization under appropriate aeration and was inhibited by Fe3+ supplementation. Candida utilis converted ethanol to ethyl acetate optimally at pH 5.0–7.0. The five‐hour rate of ester production increased as the ethanol concentration increased to 10 g/L, and rapidly declined to zero at concentrations exceeding 35 g/L. Thus, C. utilis has potential to recover dilute ethanol in the form of ethyl acetate.
An evaluation of single‐ and separated‐phase anaerobic industrial wastewater treatment in fluidized bed reactors
Authors: Bull Michael A. , Sterritt Robert M. , Lester John N. 
Published: December 2004

AbstractFour fluidized bed reactors were used to evaluate single‐and separated‐phase anaerobic treatments of a high strength wastewater. Two reactors were fed with a synthetic wastewater, containing glucose as the primary carbon source, with a COD of 1.2 × 104 mg/L while the remaining pair were fed with a wastewater with a COD of 6000 mg/L. AT each influent strength, one fluidized bed reactor was operated as a single‐phase system while the other was operated as a methanogenic reactor which was preceded by an acidification reactor in a separatedphase system. The reactors were operated under steady‐state and variable process conditions. The separated‐phase system consistently gave a better quality effluent with lower effluent suspended solids and total COD, and the methane yield was also improved. Under variable process conditions, the separated‐phase system was inherently more stable and recovered more rapidly following a shock loading. Propionate and acetate degradation studies indicated that the biomass in the methanogenic fluidized beds of the two‐phase systems was more adapted to volatile acid degradation than the biomass in the single‐phase fluidized beds.