bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pretreatment of wheat straw for fermentation to methane
Authors: Hashimoto Andrew G. 
Published: December 2004

AbstractThe effects of pretreating wheat straw with gamma‐ray irradiation, ammonium hydroxide, and sodium hydroxide on methane yield, fermentation rate constant, and loss of feedstock constituents were evaluated using laboratory‐scale batch fermentors. Results showed that methane yield increased as pretreatment alkali concentration increased, with the highest yield being 37% over untreated straw for the pretreatment consisting of sodium hydroxide dosage of 34 g OH−/kg volatile solids, at 90°C for 1 h. Gamma‐ray irradiation had no significant effect on methane yield. Alkaline pretreatment temperatures above 100°C caused a decrease in methane yield. After more than 100 days of fermentation, all of the hemi‐cellulose and more than 80% of the cellulose were degraded. The loss in cellulose and hemicellulose accounted for 100% of the volatile solids lost. No consistent effect of pretreatments on batch fermentation rates was noted. Semicontinuous fermentations of straw‐manure mixtures confirmed the relative effectiveness of sodium and ammonium‐hydroxide pretreatments.
Prevention of formation of acid drainage from high‐sulfur coal refuse by inhibition of iron‐ and sulfur‐oxidizing microorganisms. II. Inhibition in “run of mine” refuse under simulated field conditions
Authors: Dugan P. R. 
Published: December 2004

AbstractThe combination of sodium lauryl sulfate and benzoic acid effectively inhibits iron‐ and sulfur‐oxidizing bacteria in coal refuse and prevents the conversion of iron pyrite to sulfate, ferric iron, and sulfuric acid, thereby significantly reducing the formation of acidic drainage from coal refuse. The inhibitors were effective in a concentration of 1.1 mg/kg refuse, and data indicate that the SLS was in excess of the concentration required. The treatment was compatible with the use of lime for neutralization of acid present prior to inhibition of its formation.
Hydrolysis of dilute acid pretreated mixed hardwood and purified microcrystalline cellulose by cell‐free broth from Clostridium thermocellum
Authors: Lynd L. R. , Grethlein H. E. 
Published: December 2004

AbstractThe cellulase activity in cell‐free broths from the thermophilic, ethanol‐producing anaerobic bacterium Clostridium thermocellum is examined on both dilute‐acid‐pretreated mixed hardwood (90% maple, 10% birch) and Avicel. Experiments were conducted in vitro in order to distinguish properties of the cellulase from properties of the organism and to evaluate the effectiveness of C. thermocellum cellulase in the hydrolysis of a naturally occurring, lignin‐containing substrate. The results obtained establish that essentially quantitative hydrolysis of cellulose from pretreated mixed hardwood is possible using this enzyme system. Pretreatment with 1% H2SO4 and a 9‐s residence time at 220, 210, 200, and 180°C allowed yields after enzymatic hydrolysis (percentage of glucan solubilized/ glucan potentially solubilized) of 97.8, 86.1, 82.0, and 34.6%, respectively. Enzymatic hydrolysis of mixed hardwood with no pretreatment resulted in a yield of 10.1%. Hydrolysis yields of >95% were obtained from ∼0.6 g/L mixed hardwood pretreated at 220°C in 7 h at broth strengths of 60 and 80% (v/v) and in approximately 48 h with 33% broth. Hydrolysis of pretreated mixed hardwood is compared to hydrolysis of Avicel, a pure microcrystalline cellulose studied previously. The initial rate of Avicel hydrolysis saturates with respect to enzyme, whereas the initial rate of hydrolysis of pretreated wood is proportional to the amount of enzyme present. Initial hydrolysis rates for pretreated wood and Avicel at 0.6 g/L are greater for wood at low broth dilutions (1.25: 1 to 5 :1) by up to 2.7‐fold and greater for Avicel at high broth dilutions (5 : 1 to 50 : 1) by up to 4.3‐fold. Maximum rates of hydrolysis are achieved at <2 g substrate/L for both pretreated wood and Avicel. The substrate concentration at one‐half the maximum observed rate for C. thermocellum broths is smaller for pretreated mixed hardwood than for Avicel and decreases with increasing broth dilution for both substrates. An initial activity per volume broth of approximately 11 μmol soluble glucose equivalent produced/L broth/min is observed for mixed hardwood pretreated at 220°C and for Avicel at high broth dilutions; the initial activity per volume broth for Avicel is lower at low broth dilutions. The results indicate that pretreated wood is hydrolyzed at rates comparable to Avicel under many conditions and at rates significantly faster than Avicel under several conditions.
Cellulase immobilized on poly‐L‐glutamic acid
Authors: Takeuchi Tamio , Makino Keisuke 
Published: December 2004

AbstractCellulase (Cellulosin AC‐8) was immobilized on poly‐L‐glutamic acid. This immobilized cellulase (IC) is water soluble in the neutral and alkaline solutions, where IC has the activity, while IC can be made insoluble by lowering the pH so that it can be recovered from the reaction mixture with its activity. The optimum pH and temperature were determined to be 5.5 and 55°C, respectively. The stability of IC against change in the pH and temperature was improved by the immobilization. Solvolysis of 3N‐NaOH‐treated cellulose, with IC under the optimum conditions found here, led to the production of low‐molecular‐weight compounds.
Modeling and static optimization of the ethanol production in a cascade reactor. II. Static optimization
Authors: Dourado A. , Calvet J. L. , Sevely Y. , Goma G. 
Published: December 2004

AbstractIn Part I1 of this research a complex model was obtained for describing the ethanol fermentation in a cascade reactor. This complexity is due to both the nonlinearity and the large scale representation. Based on techniques of partitioning and relaxation, a decentralized successive approximation method is developed for static optimization. The influence of the way of fermentation during continuous culture in multistage fermentors is studied in the case of a double inhibition of cell growth and product formation by both substrate and final product. The optimal number of reactors is discussed with respect to the strength of the ethanol inhibition, while the interest of head feeding or distributed feeding is evaluated in relation to the strength of substrate inhibition.
Chronocoulometric techniques in the study of computerized enzyme electrode systems
Authors: Rishpon J. 
Published: December 2004

AbstractThe electrochemical transient of a two‐substrate enzyme electrode was studied theoretically and experimentally. Operation of such electrodes in the chronocoulometric mode leads to increased electrode sensitivity and makes possible the retrieval of useful information on transport and kinetics parameters. Digital simulation was used to solve the kinetics and transport equations and to produce the theoretical chronocoulometric response. A glucose electrode based on glucose oxidase crosslinked to different matrices was tested with air oxygen and p‐benzoquinone as the cosubstrate. A computerized electrochemical system was employed for electrode potential control and data acquistion and analysis.
Oxidation of hydrogen sulfide by Thiobacillus denitrificans: Desulfurization of natural gas
Authors: Sublette Kerry L. , Sylvester Nicholas D. 
Published: December 2004

AbstractIt has been demonstrated that Thiobacillus denitrificans may be readily cultivated anaerobically in batch reactors on H2S (g) under sulfide‐limiting conditions. Under these conditions sulfide concentrations in the culture medium were less than 1 μM, resulting in very low concentrations of H2S in the reactor outlet gas. The stoichiometry of the reaction was determined, and stable reactor operation was demonstrated at reactor loadings as high as 4–5 mmol H2S oxidized/h g biomass. Maximum loading was estimated at 5.4–7.6 mmol H2S/h g biomass under the conditions employed in this study. Indicators of reactor upset were determined and recovery from upset conditions demonstrated. Barotolerance of T. denitrificans to 12.5 MPa as well as a relative insensitivity to pressurization–depressurization cycles were also demonstrated. T. denitrificans was observed to be very sensitive to CH3SH but relatively tolerant of CS2, COS, and CH3SCH3.
Modeling bisubstrate removal by biofilms
Authors: Namkung Eun , Rittmann Bruce E. 
Published: December 2004

AbstractA bisubstrate secondary utilization model is based on the concept that an individual substrate can be utilized not only by the biomass by its utilization but also by the biomass made from the utilization of the other substrate. When substrate concentrations are low, a key factor is having sufficient substrate to initiate biofilm growth. Modeling results for three characteristic cases demonstrate that satisfying a total Smin concentration for a bisubstrate system is the necessary condition for initiating biofilm growth and simultaneous utilization of both substrates. Because having more than one substrate supporting biofilm growth enhances the removal of each compound, the utilization rate of a specific compound can be increased by the concentration of other compounds, and the total Smin concentration can be less than the weighted average of individual Smin values.
Energetic analysis of the growth of Methanobrevibacter arboriphilus A2 in hydrogen‐limited continuous cultures
Authors: Morii Hiroyuki , Koga Yosuke , Nagai Shiro 
Published: December 2004

AbstractHydrogen‐limited chemostat cultures of Methanobrevibacter arboriphilus A2 were carried out. The available electron balance and carbon balance in M. arboriphilus A2 and other methanogenic strains grown on various substrates were well satisfied. This indicates that no extracellular organic products were formed during methanogenic growth. The molar growth yields for methane (Y) were calculated as 1.06–1.42 g cell/mol CH4 at dilution rate (0.21–0.43 day−1). The smaller Y of M. arboriphilus A2 compared with that of the other methanogenic strains was probably owing to the low growth rate of M. arboriphilus A2. The low value of Y may be favorable for methane fermentation because less sludge accumulation is expected. The efficiency of free energy transduction to ATP during methane formation from H2 + CO2 was 12–17% at the dilution rate (0.21–0.43 day−1) assuming that YATP was 6.5 g/mol and the free energy change of CO2 reduction to methane with H2 was −62.8 kJ/mol under physiological conditions.
The effect of pH and lactose concentration on solvent production from whey permeate using Clostridium acetobutylicum
Authors: Ennis B. M. , Maddox I. S. 
Published: December 2004

AbstractA study was performed to optimize the production of solvents from whey permeate in batch fermentation using Clostridium acetobutylicum P262. Fermentations performed at relatively low pH values resulted in high solvent yields and productivities, but lactose utilization was incomplete. At higher pH values, lactose utilization was improved but acid production dominated over solvent production. When operating at the higher pH values, an increase in the initial lactose concentration of the whey permeate resulted in lower rates of lactose utilization, and this was accompanied by increased solvent production and decreased acid production. Analysis of data from several experiments revealed a strong inverse relationship between solvent yield and lactose utilization rate. Thus, conditions which minimize the lactose utilization rate, such as low culture pH values or high initial lactose concentrations, favor solventogenesis at the expense of acid production.
Low‐pressure airlift fermenter for single cell protein production: I. Design and oxygen transfer studies
Authors: Chen N. Y. , Kondis E. F. , Srinivasan S. 
Published: December 2004

AbstractThe energy consumption of a fermenter constitutes a major part of the operating expense of a single cell protein process. A low‐pressure airlift fermenter was designed to reduce this cost. In this new design, the fermenter broth is kept below 120 cm in depth, and air alone is employed to fulfill the need of supplying oxygen, and cooling and agitating the broth. The use of low‐pressure air from air blowers instead of air compressors lowers the capital cost of air delivery and reduces the energy consumption in the fermenter section to below 1 kWh/kg protein, a saving of over 70% as compared to a conventional stirred tank fermenter. It also eliminates the investment of mechanical agitators, heat exchangers, and air compressors. Sulfite oxidation studies confirmed the design concepts.
Physicochemical factors affecting ethanol adsorption by activated carbon
Authors: Bradley K. J. , Hamdy M. K. , Toledo R. T. 
Published: December 2004

AbstractPowder and granular activated charcoal were evaluated for ethanol adsorptivity from aqueous mixtures using an adsorption isotherm. Ethanol adsorption capacity was more pronounced at 25°C as compared to 5, 15, and 40°C. When pH of the ethanol–buffer mixture (0.09 ionic strength) was changed from acidic (2.3) to neutral and then to alkaline (11.2), ethanol adsorption was decreased. Increasing ionic strength of the ethanol‐buffer mixtures from 0.05 to 0.09 enhanced ethanol adsorption but a further increase to 0.14 showed no significant effect. Ethanol adsorption was more efficient from an aqueous ethanol mixture as compared to semidefined and nondefined fermentation worts, respectively. Heating granular charcoal to 400°C for 1 h and 600°C for 3 h in N2 increased ethanol adsorptivity and heating to 1000°C (1 h) in CO2 decreased it when ethanol was removed from dilute solutions by simple pass adsorption in a carbon packed column. Granular charcoal was superior to powdered charcoal and an inverse relationship was noted between the weight of the granular carbon bed in the column and ethanol adsorbed/g carbon. Decreasing the column feed flow rate from 7.5 to 2.0 L aqueous ethanol/min increased the adsorption rate.
Evaluation of Escherichia coli and Candida utilis as a model continuous, competitive mixed culture system
Authors: Goochee Charles F. , Hatch Randolph T. , Cadman Theodore W. 
Published: December 2004

AbstractThe yeast Candida utilis and the bacterium Escherichia coli B/r were evaluated as a candidate experimental, continous, competitive mixed culture system under ammonia–nitrogen limited conditions at 30°C. High dilution rates favored yeast dominance, while low dilution rates favored bacterial dominance. The hydrogen ion concentration was also demonstrated to be an effective manipulative variable for control of the yeast–bacterial mixed culture. Through trial‐and‐error manipulation of the pH for the mixed culture operating at constant dilution rate, it was possible to locate a metastable equilibrium point and to operate in the vicinity of that point for more than 24h. The reproducible emergence of a variant E. coli was also noted in this study.
Effect of a broad‐host range plasmid on growth dynamics of Escherichia coli and Pseudomonas putida
Authors: De Bernardez Eliana R. , Dhurjati Prasad S. 
Published: December 2004

AbstractHost–plasmid interactions were studied for the broad‐host range plasmid, pTJS26, a derivative of RK2. To isolate host and plasmid contributions to the growth dynamics and plasmid stability, separate experiments were performed with host and recombinant cells for two different gram‐negative hosts, Pseudomonas putida and Escherichia coli, at two different temperatures, 30 and 37°C. At the lower temperature (30°C) the growth kinetics were not affected by the plasmid, but plasmid instability was observed. At the higher temperature (37°C) growth rates and yields were lower than that for the hosts, but the plasmid was stable. This behavior can be explained by a combination of two phenomena. First, the copy number control mechanism may be temperature sensitive and, second, plasmid segregation may be inefficient. For both E. coli and P. putida the growth dynamics of the recombinant system was dictated by the presence of the plasmid.
Evaluation of organosolv processes for the fractionation and modification of corn stover for bioconversion
Authors: Lee Yong‐Hyun , Robinson Campbell W. , Moo‐Young M. 
Published: December 2004

AbstractCorn stover was pretreated for compositional fractionation and structural modification for maximum conversion of carbohydrate to soluble sugars. The process scheme consisted of three steps: (1) mild prehydrolysis in dilute sulfuric acid, (2) delignification with various organosolv solvents, and (3) enzymatic hydrolysis in an agitated bead reactor. Prehydrolysis of corn stover can be achieved at temperatures ranging from 95 to 120°C, which is a much milder condition than must be applied to wood. Various organosolv solvents, including several alcohols with acid as catalyst, ethylene glycol, and its derivatives, and amines were used for delignification of the prehydrolyzed corn stover. Aromatic alcohols were found to be more effective in solubilizing the prehydrolyzed corn stover than were the aliphatic alcohols. Butanol was the most effective among the aliphatic alcohols; on the other hand, phenol was the best among the aromatic alcohols. Ethylene glycol, methylcellosolv, and ethylcellosolv were effective in solubilizing the prehydrolyzed corn stover but not for enhancing the enzymatic hydrolysis. Various amines achieved delignification at the mild temperature of 95°C, but they tended to solubilize substantial amounts of carbohydrate in addition to lignin. n‐Butylamine was effective in enhancing the conversion during enzymatic hydrolysis; it was a good delignifying agent as well as one that achieved a concomitant swelling of the cellulose structure. The low enzymic conversion (20–37%) of prehydrolyzed and solvent‐extracted corn stover that was achieved implies that lignin is not the only major barrier for enzymatic hydrolysis. Modification of cellulose structure also should be accomplished to achieve a high degree of conversion. Enzymatic hydrolysis in the agitated bead system increased the rate and extent of conversion of corn stover substantially compared to systems without beads.
Coexistence of bacteria and feeding ciliates: Growth of bacteria on autochthonous substrates as a stabilizing factor for coexistence
Authors: Sambanis A. , Pavlou S. , Fredrickson A. G. 
Published: December 2004

AbstractThere is good evidence that the specific feeding and growth rates of a population of suspension‐feeding ciliates on a population of bacteria is described by the classic Monod model or something very like it. However, use of this model combined with the assumption that feeding of the ciliates is the only interaction between the populations leads to predictions grossly at variance with experimental observations. A second interaction between the populations, growth of the bacteria on products of lysis, and perhaps metabolism of the ciliates is known to occur and might be an important factor in determining the dynamics of ciliate–bacterial systems. Whether or not this is the case is examined in the present article. It is concluded that accounting for the second interaction does not remove the discrepancies between model predictions and experimental observations. It is concluded also that the second interaction is likely not important except in batchtype situations where the supply of available energy for supporting biological activity is not replenished.
Alcohol fermentation of corn starch digested by Chalara paradoxa amylase without cooking
Authors: Mikuni Katsuhiko , Monma Mitsuru , Kainuma Keiji 
Published: December 2004

AbstractAlcohol fermentation of corn starch without cooking was performed by using Chalara paradoxa glucoamylase preparation, which had stronger raw starch digesting activity than those of the conventionally known glucoamylases. A raw corn starch–enzyme–yeast mixture was fermented optimally at pH 5.0 and 30°C for five days and produced ethanol. The yields of ethanol were between 63.5 and 86.8% of the theoretical value by baker's yeast (Saccharomyces cerevisiae), and between 81.1 and 92.1% of the theoretical value by sake yeast (Saccharomyces sake).
Purification of an extracellular cellulose‐binding endoglucanase of Cellulomonas sp. ATCC 21399 by affinity chromatography on H3PO4‐swollen cellulose
Authors: Poulsen Otto M. , Petersen Lars W. 
Published: December 2004

AbstractA cellulose‐binding endoglucanase (endoglucanase A) of Cellulomonas sp. ATCC 21399 was purified to immunological homogeneity by affinity chromatography ob H3PO4‐swollen cellulose. This method of purification turned out to be an easy and very gentle method for obtaining a high yield of cellulose‐binding endoglucanase. The purified enzyme was immunologically homogeneous but appeared heterogeneous when analyzed by denaturing polyacrylamide gel electrophoresis. In addition to the cellulose‐binding of endoglucanase A, the enzyme also had a strong affinity for Concanavaline A, indicating that the enzyme was glycosylated. Purified endoglucanase A showed an endo mode of action on carboxymethylcellulose. The enzyme could hydrolyze microcrystalline cellulose when acting alone, and the enzyme had a high specific activity on H3PO4‐swollen cellulose.
Investigation of plasmid instability in amylase‐producing B. subtilis using continuous culture
Authors: Kadam Kiran L. , Wollweber Karen L. , Grosch Josephine C. , Jao Yun C. 
Published: December 2004

AbstractContinuous culture was employed to study plasmid instability in an amylase‐producing Bacillus subtilis 1A289 that was genetically manipulated. No true steady state could be obtained with 1A289(pEAA)‐strain (plasmid)‐due to its structural instability, which occurred both with glucose and Maltrin‐100 as limiting carbon sources. The plasmid, pEAA (CmR, amy+, i.e., chloramphenicol resistant, amylase positive) degenerated into a smaller plasmid, pEAA1 (CMR, amy−) that was stable. There was a direct correlation between amylase‐producing ability and this structural instability since famy (fraction of cells with amylase‐producing ability) reached zero at the same time that f (fraction of cells that are resistant to chloramphenicol) reached its maximum level. Since the deletion in pEAA was larger than the original amylase‐gene insert, either all of part of the insert is absent from pEAA1. Though on discernible change in 1A289(pHV33), where pHV33 is the vector plasmid, was observed during continuous cultivation, its behavior was different from that of the stable 1A289(pEAA1).
Isolation and purification of protease from human placenta by foam fractionation
Authors: Sarkar P. , Bhattacharya P. , Mukherjea R. N. , Mukherjea M. 
Published: December 2004

AbstractThe effect of operating parameters like pH, protein concentration, column geometry, and gas flow rate on the separation efficiency of proteolytic enzymes from crude human placental homogenate has been studied in a batch foam column. Purification has been found to be optimum at pH 8.0, close to the isoelectric pH, at which the surface adsorption of the protein on the foam bubbles is maximum. Both purification and recovery varied significantly with total protein concentration. Stable bubble formation was hindered at lower protein concentrations, while extraneous proteins rather than the protease were preferentially adsorbed at higher protein concentrations, decreasing the purification efficiency. Column diameter and column height should be optimized for any specific feed protein concentration and gas flow rate. However, the enrichment ratio was found to decrease with the increase in flow rate. The results indicate that foam fractionation is an effective separation process for recovering valuable biochemicals from biological materials.