bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of nitrification and denitrification reactions
Authors: Shah Dhananjai B. , Coulman George A. 
Published: December 2004

AbstractNitrification and denitrification are important microbiological reactions of nitrogen. In this work, the kinetics of these reactions have been investigated based on a Monod‐type expression involving two growth limiting substrates: ammonium nitrogen and dissolved oxygen for nitrification and nitrate nitrogen and dissolved organic carbon for denitrification. The kinetic constants and yield coefficients were evaluated for both these reactions. Past experimental work was used to determine the constants for the nitrification reaction. For the denitrification reaction, experiments were performed in a stirred tank reactor under conditions such that only one substrate was growth limiting. Steady‐state values of the substrate concentrations in the reactor were determined at various dilution rates. These data were analyzed to obtain the kinetic and stoichiometric constants. From these constants it was concluded that in the range of nitrate nitrogen concentrations encountered in waste water, the denitrification reaction can be considered a first‐order reaction. It was also found that three times as much organic carbon is required as nitrate nitrogen for complete nitrogen removal.
Single cell protein from various chemically pretreated wood substrates using Chaetomium cellulolyticum
Authors: Moo‐Young M. , Chahal D. S. , Vlach D. 
Published: December 2004

AbstractThe growth behavior of Chaetomium cellulolyticum, a new cellulolytic fungus, has been examined in slurry fermentation systems using various chemically pretreated sawdusts from hardwoods as substrates. Both acid‐ and alkali‐pretreatment methods were used and the fermentation media included the spent pretreatment liquor in an attempt to concurrently maximize substrate utilization and minimize the biological oxygen demand (BOD) level in the process effluent. Diauxic growth patterns were found in the three cases studied, suggesting an initial utilization of soluble hemicellulose sugars followed by utilization of the insoluble cellulose. This behavior patterns was supported by separate growth experiments using the major sugars of hemicellulose as carbon sources. The organism was found to be a good convertor of both cellulose and hemicelluloses into single cell protein (SCP). In terms of rate and extent of protein production in the insoluble biomass product, acid pretreatment appears to be better than alkali pretreatment if the product is intended as ruminant feed.
Citric acid production from glucose. I. Growth and excretion kinetics in a stirred fermentor
Authors: Briffaud Joseph , Engasser Jeanmarc 
Published: December 2004

AbstractThe growth and citric acid production kinetics of Saccharomycopsis lipolytica on glucose are investigated in an aerated stirred fermentor. Cellular growth first proceeds exponentially until exhaustion of ammonia in the fermentation medium. Cells then continue to grow at a reduced rate with a concomitant decrease in intracellular nitrogen content. Citric and isocitric acid production starts at the end of the growth phase. During about 80 hr excretion proceeds at a constant rate of 0.7 g/liter/hr for citric acid and 0.1 g/liter/hr for isocitric acid. The final citric and isocitric acid concentrations are 95 and 10g/liter, respectively. During acid excretion cellular respiration accounts for 60 and 35% of consumed oxygen and glucose. Both acid and CO2 production rates follow a Michaelis–Menten‐type dependence on oxygen concentration with Michaelis–Menten constants of 0.9 and 0.15 mg/liter for acid and CO2 productions, respectively.
Citric acid production from glucose. II. Growth and excretion kinetics in a trickleflow fermentor
Authors: Briffaud Joseph , Engasser Jeanmarc 
Published: December 2004

AbstractThe growth and citric acid production kinetics of Saccharomycopsis lipolytica on glucose is investigated in a trickle‐flow fermentor. Liquid hold‐up and oxygen‐transfer coefficient in the reactor column filled with cylindrical wood chips have been determined and found in agreement with chemical engineering correlations. Citric acid production starts at the end of the growth phase and proceeds at a constant specific rate of 0.025 hr−1for about 80 hr. The fermentor can then be regenerated by addition of ammonia, which induces new growth and excretion phases. Comparing the metabolic behavior of free and immobilized cells, two main kinetic differences are observed. First, the growth phase is linear with the bound cells instead of exponential in the stirred fermentor. Second, in the trickle‐bed fermentor acid productivity and oxygen acid yield are reduced by 30%. Oxygen diffusional limitations, mainly in the biomass film, and alterations in bound cell metabolism are shown to be responsible of the kinetic modifications. Simple modelizations of oxygen diffusion effects are also presented to support the interpretation of the experimental data.
Production of ethanol from raw cassava starch by a nonconventional fermentation method
Authors: Ueda Seinosuke , Zenin Celia T. , Monteiro Domingos A. , Park Yong K. 
Published: December 2004

AbstractRaw cassava root starch was transformed into ethanol in a one‐step process of fermentation, in which are combined the conventional processes of liquefaction, saccharification, and fermentation to alcohol. Aspergillus awamori NRRL 3112 and Aspergillus niger were cultivated on wheat bran and used as Koji enzymes. Commercial A. niger amyloglucosidase was also used in this experiment. A raw cassava root homogenate–enzymes–yeast mixture fermented optimally at pH 3.5 and 30°C, for five days and produced ethanol. Alcohol yields from raw cassava roots were between 82.3 and 99.6%. Fungal Koji enzymes effectively decreased the viscosity of cassava root fermentation mashes during incubation. Commercial A. niger amyloglucosidase decreased the viscosity slightly. Reduction of viscosity of fermentation mashes was 40, 84, and 93% by commercial amyloglucosidase, A. awamori, and A. niger enzymes, respectively. The reduction of viscosity of fermentation mashes is probably due to the hydrolysis of pentosans by Koji enzymes.
Organic acid production from CO2/H2 and CO/H2 by mixed‐culture anaerobes
Authors: Levy P. F. , Barnard G. W. , Garcia‐Martinez D. V. , Sanderson J. E. , Wise D. L. 
Published: December 2004

AbstractThe gases CO, CO2, and H2 were used as substrates in anaerobic fermentations producing organic acids. Various mixed bacterial sources were used, including sewage sludge digester effluent, rabbit feces, and soil. Nonsterile microorganism selection was carried out using CO2/H2 and CO/H2 as the primary carbon and energy sources. Cultures were grown in specially designed, high‐pressure (to 70 psig) flasks. Methanogenic bacteria were eliminated from the cultures. Liquid products of the fermentations were acetic through caproic acids, with the even‐numbered acids predominating. Carbon balances showed conclusively that acetic acid was formed from carbon contained in the CO or CO2 feed gas. Measurements made included rates of acid product formation, cell density, and degree of gas utilization. Limited characterization of the microorganisms was also performed. Production of organic acids by mixed culture inocula from CO2/H2 or CO/H2 had not been reported previously. Application of this work is to the production of organic chemicals from synthesis gas (SNG), produced by the gasification of fossil fuels (peat, lignite, and various ranks of coals), biomass (agricultural and forest residues, and various biomass crops grown expressly for energy recovery), and municipal solid waste.
Effect of compression milling on cellulose structure and on enzymatic hydrolysis kinetics
Authors: Ryu Dewey D. Y. , Lee Sun Bok , Tassinari T. , Macy C. 
Published: December 2004

AbstractThe changes in the cellulose structure by compression milling were studied and expressed in terms of crystallinity, accessibility, specific surface area, and degree of polymerization. The kinetic parameters, maximum reaction rate, and Michaelis constant were determined experimentally. Based on the experimental results a two‐phase model, which is based on the degradation of cellulose by simultaneous actions of the cellulase complex on the crystalline and amorphous phases, is proposed. The relationships between cellulose accessibility and the kinetic parameters were compared with those predicted by the model. A good agreement was found, although the two‐phase hypothesis is a simplification of the true state of order in cellulose.
Ethanol production by immobilized Saccharomyces cerevisiae, Saccharomyces uvarum, and Zymomonas mobilis
Authors: McGhee J. E. , Julian G. St. , Detroy R. W. , Bothast R. J. 
Published: December 2004

AbstractSaccharomyces cerevisiae NRRL Y‐2034, S, uvarum NRRL Y‐1347, and Zymomonas mobilis NRRL B‐806 each were separately immobilized in a Ca‐alginate matrix and incubated in the presence of a free‐flowing and continuous 1, 3, 5, 10, or 20% (w/w) glucose solution. In general, the yeast cells, converted 100percnt; of the 1, 3, and 5% glucose to alcohol within 48 h and maintained such a conversion rate for at least two weeks. The bacterium converted ca. 90% (w/w) of the 1, 3, and 5% glucose to alcohol continuously for one week. However, both the yeast and bacterium were inhibited in the highest glucose (20% w/w) solution. All of the immobilized cultures produced some alcohol for at least 14 days. Immobilized S. cerevisiae was the best alcohol producer of all of the glucose concentrations; the yeast yielded 4.7 g ethanol/100 g solution within 72 h in the 10% glucose solution. After 7–8 days in the 10% solution, S. cerevisiae produced ethanol at 100% of theoretical yield (5.0 g ethanol/100 g solution), with a gradual decrease in alcohol production by 14 days. Immobillized S. uvarum produced a maximum of 4.0 g ethanol/100 g solution within 2 days and then declined to ca. 1.0 g ethanol/100 g solution after 7 days continuous fermentation in the 10% glucose solution. Zymomonas mobilis reached its maximum ethanol production at 4 days (4.7 g/100 g solution), and then diminished similarly to S. uvarum. The development of a multiple disk shaft eliminated the problem both of uneven distribution of alginate‐encapsulated cells and of glucose channeling within the continuous‐flow fermentor column. This invention improved alcohol production about threefold for the yeast cells.
Development of a direct digital‐controlled fermentor using a microminicomputer hierarchical system
Authors: Rolf Michael J. , Hennigan Paul J. , Mohler Robert D. , Weigand William A. , Lim Henry C. 
Published: December 2004

AbstractA computerized fermentation system was developed for use in a research environment. Major goals in the design and construction of the system were flexibility and versatility. Direct digital control is employed for all low‐level and high‐level control loops. A microminicomputer hierarchical configuration is used to implement this control structure. The microcomputer is also utilized to simplify the interface with the fermentor, both at the hardware and minicomputer software levels. This computerized fermentation system provides accurate data acquisition, excellent control, and flexibility in the fermentation operation.
Continuous ethanol production from Jerusalem artichoke tubers. II. Use of immobilized cells of Kluyveromyces marxianus
Authors: Margaritis Argyrios , Bajpai Pratima 
Published: December 2004

AbstractKluyveromyces marxianus UCD (FST) 55–82 cells were immobilized in Na alginate beads and used in a packed‐bed bioreactor system for the continuous production of ethanol from the extract of Jerusalem artichoke tubers. Volumetric ethanol productivities of 104 and 80 g ethanol/ L/h were obtained at 80 and 92% sugar utilization, respectively. The maximum volumetric ethanol productivity of the immobilized cell bioreactor system was found to be 15 times higher than that of an ordinary‐stirred‐tank (CST) bioreactor using cells of K. marxianus. The immobilized cell bioreactor system was operated continuously at a constant dilution rate of 0.66 h−1 for 12 days resulting in only an 8% loss of the original immobilized cell activity, which corresponds to an estimated half‐life of ca. 72 days. The maximum specific ethanol productivity and maximum specific sugar uptake rate of the immobilized cells were found to be 0.55 g ethanol/g/biomass/h and 1.21 g sugars/g biomass/h, respectively.
Hydrogen production by a green alga, Chlamydomonas reinhardtii, in an alternating light/dark cycle
Authors: Miura Yoshiharu , Yagi Kiyohito , Shoga Mitsuru , Miyamoto Kazushisa 
Published: December 2004

AbstractThe evolution of H2 in the dark period of a light/dark cycle by a green alga, Chlamydomonas reinhardtii, was studied with the aim of developing a two/stage biophotolysis system. The algal cells accumulated starch during the growth period in light. When these cells were incubated microaerobically in the dark, hydrogenase activity was induced was induced without an appreciable lag time and therapy H2 evolution was observed for several hours to more than 10 h, depending upon the amount of added O2. The cells harvested in the midlogarithmic growth phase were the most efficient in production of H2 in the dark. H2 evolution was highly dependent on temperature, but rather incentive to pH values from 5–9. Based on these observations, altering production of O2 and H2 was demonstrated repeatedly in a light/dark cycle.
Immobilization of mold and bacterial amylases on silica carriers
Authors: Kvesitadze G. I. , Dvali M. Sh. 
Published: December 2004

AbstractThe immobilization of α‐amylase and glucoamylase was investigated by several coupling methods on silica carriers, different types of Silokhroms, and silica gels. The most active immobilized mold and bacterial α‐amylases and mold glucoamylase were obtained with titanium salts. These activities were twice the value of that obtained by glutaraldehyde or azo coupling. The half‐lives of A. oryzae α‐amylase, B. subtilis α‐amylase, and A. niger glucoamylase, immobilized to silica carriers at 45°C and under continuous operation at a high concentration of substrate, were 14, 35, and 65 days, respectively.
Exploitation of plant cells for the production of natural compounds
Authors: Deus B. , Zenk M. H. 
Published: December 2004

AbstractA four‐step strategy is presented which allows the establishment of plant cell cultures producing high yields of secondary plant products. The application of suitable methods (radioimmunoassay, fluorescence screening) for the selection of overproducing differentiated plants and cell colonies is stressed. By precursor feeding and hormone application, plant cell cultures can greatly be influenced in their production behavior. A highly sensitive, selective regulatory mechanism for the uptake and storage of alkaloids in Catharanthus vacuoles is demonstrated. Overproducing variant cell strains are so far the most promising tool for the future biotechnological application of the plant cell culture method.
Methane from cattle waste: Effects of temperature, hydraulic retention time, and influent substrate concentration on kinetic parameter (k)
Authors: Hashimoto Andrew G. 
Published: December 2004

AbstractThe effects of temperature (35 and 55°C), influent volatile solids (VS) concentration (S0 = 43, 64, 82, 100, and 128 kg VS/m3) and hydraulic retention time (HRT = 4, 5, 8, 10, 15, and 25 days) on methane (CH4) production from cattle waste were evaluated using 3‐dm3 laboratoryscale fermentors. The highest CH4 production rate achieved was 6.11 m3 CH4 m−3 fermentor day−1 at 55°C, four days HRT, and S0 = 100 kg VS/m3. Batch fermentations showed an ultimate CH4 yield (B0) of 0.42 m3 CH4/kg VS fed. The maximum loading rates for unstressed fermentation were 7 kg VS m−3 day−1 at 35°C and 20 kg VS m−3 day−1 at 55°C. The kinetic parameter (K, an increasing K indicates inhibition of fermentation) increased exponentially as S0 increased, and was described by: K = 0.8 + 0.0016 e. Temperature had no significant effect on K for S0 between 40 and 100 kg VS/m3. The above equation predicted published K values for cattle waste within a mean standard error of 7%.
The properties of immobilized caldolysin, a thermostable protease from an extreme thermophile
Authors: Cowan Donald A. , Daniel Roy M. 
Published: December 2004

AbstractCaldolysin, the extracellular thermostable metal‐chelator‐sensitive lytic protease from Thermus T‐351 was immobilized to Sepharose 4B, CM‐cellulose, and controlled pore glass (CPG). Although protein binding efficiencies were high (96, 88, and 95%), some loss of enzyme activity occurred on immobilization (26, 69, and 89%). The pH optimum of both CM‐cellulose and CPG‐immobilized Caldolysin was decreased by about one pH unit. The Km for Sepharose‐Caldolysin was unchanged with respect to the free protease, while those for CM‐cellulose‐Caldolysin and CPG‐Caldolysin were lower by approximately one order of magnitude. Immobilization to both Sepharose and CM‐cellulose increased the thermostability of Caldolysin at high temperatures, while CPG‐Caldolysin was less thermostable than the free protease.
Bioconversion of waste cellulose by using an attrition bioreactor
Authors: Ryu S. K. , Lee J. M. 
Published: December 2004

AbstractA new type of reactor, an attrition bioreactor, was tested to achieve a higher rate and extent of enzymatic saccharification of cellulose than is possible with conventional methods. The reactor consisted of a jacketted stainless‐steel vessel with shaft, stirrer, and milling media, which combined the effect of the mechanical action of wet milling with cellulose hydrolysis. The substrates tested were newsprint and white‐pine heartwood. The performance of the reactor was excellent. The extent and rate of enzymatic hydrolysis could be markedly improved over other methods. The power consumption of the attrition bioreactor was also measured. The cellulase enzyme deactivation during attrition milling was not significant.
Reduction of acetoin to 2,3‐butanediol in Klebsiella pneumoniae: A new model
Authors: Voloch M. , Ladisch M. R. , Rodwell V. W. , Tsao G. T. 
Published: December 2004

AbstractFermentation of xylose by Klebsiella pneumoniae (ATCC 8724, formerly known as Aerobacter aerogenes) carried out in our laboratory yields 2,3‐butanediol as the major product. Experimental data obtained in this work cannot be explained by the model presently in the literature for the formation of 2,3‐butanediol isomers from acetoin isomers. A new model is proposed with the existence of two acetoin reductases and an acetoin racemase. The two reductases were separated and their stereospecificity determined. Extension of the model of other microorganisms is discussed.
Conversion of straw–manure mixtures to methane at mesophilic and thermophilic temperatures
Authors: Hashimoto Andrew G. 
Published: December 2004

AbstractThe effects of temperature (35 and 55°C) and straw–manure mixtures (90, 75, 50, and 0% straw) on methane (CH4) production were studied using laboratory‐scale fermentors. Batch fermentations showed that the ultimate CH4 yield (B0) of straw–manure mixtures was directly proportional to the relative proportion and B0 of the individual components. Also, hammer or ball milling did not increase the B0 of straw. Kinetic analysis showed that fermentation stress occurred when the straw content of straw–manure mixtures was higher than 40% at 35°C, or higher than 75% at 55°C. This fermentation stress was observed to occur when the free ammonia concentration was below 10 g/m3.
Immobilization of fumarase by entrapment of rat liver mitochondria in polyacrylamide gel using gamma rays
Authors: Godbole S. S. , Kaul Rajni , D'Souza S. F. , Nadkarni G. B. 
Published: December 2004

AbstractA stable immobilized preparation of fumarase (EC 4.2.1.2) was obtained by entrapment of rat liver mitochondria in acrylamide polymerized by using gamma irradiation (100 kR). The enhanced stability and the efficiency of the entrapped enzyme have shown potential for repeated use for the production of L‐malic acid from fumaric acid. The possible formation of succinic acid in the system could be controlled by incorporating malonate along with detergents such as sodium deoxycholate or sodium dodecylsulfate in the reactor system.
Preparation and performance of immobilized yeast cells in columns containing no inert carrier
Authors: Hsiao Humg‐Yu , Chiang Lin‐Chang , Yang Che‐Ming , Chen Li‐Fu , Tsao George T. 
Published: December 2004

AbstractSchizosaccharomyces pombe was cultivated in a medium of glucose (10 g/L) malt extract (3 g/L), yeast extract (3 g/L), and bactopeptone (5 g/L) to form flocs. More than 95% of the cell population were flocculated. Variation in glucose concentration (from 10 to 100 g/L) did not affect flocculation. Yeast extract helped induce flocculation. Application of the immobilized yeast for the continuous production of ethanol was tested in a column reactor. Soft yeast flocs (50–200 mesh) underwent morphological changes to heavy particles (0.1–0.3 cm diameter) after continuously being fed with fresh substrates in the column. Productivity as high as 87 g EtOH L−1 h−1 was obtained when a 150 g/L glucose medium was fed. The performance of this yeast reactor was stable over a two‐month period. The ethanol yield was 97% of the theoretical maximum based upon glucose consumed.
Kinetics and mechanism of acyl transfer by penicillin acylases
Authors: Konecny Jan , Schneider André , Sieber Meinrad 
Published: December 2004

AbstractThe hypothesis that at least some penicillin acylases react via an acyl–enzyme intermediate was tested by kinetic investigations involving the methyl ester of cyanoacetic acid as the acyl donor, deacetyl‐7‐aminocephalosporanic acid as the acyl receptor, and penicillin acylase (E.C.3.5.1.11) from B. megaterium ATCC 14945 as the catalyst. The results obtained at low concentrations of the acyl receptor are in accord with the derived rate equations. Deviations observed at higher concentrations of the acyl receptor are discussed together with some practical implications of the mechanism.
An immobilized two‐enzyme system (fungal α‐amylase/glucoamylase) and its use in the continuous production of high conversion maltose‐containing corn syrups
Authors: Hausser Alexander G. , Goldberg Bruce S. , Mertens John L. 
Published: December 2004

AbstractFungal α‐amylase (E.C. 3.2.1.1) and glucoamylase (E.C. 3.2.1.3) were chemically attached to separate reactor modules made from Microporous Plastic Sheet (MPS). Immobilization of enzymes and subsequent chemical reactions were accomplished by pumping reactants through the sheet, i.e., perpendicular to the surface. The expressed activity of the reactor modules was ca. 800 U/g for both fungal α‐amylase and glucoamylase. The kinetics and short‐term effects of pH and temperature on the expressed activity of the immobilized enzymes were investigated. Using commercially available DE‐42 corn syrup at 50% dissolved solids, half‐lives of 2000 and 5000 h were achieved for glucoamylase and fungal α‐amylase, respectively. The reactors were operated at 50°C and at pH 4.3 for glucoamylase and 5.5 for fungal α‐amylase. A typical DE‐62 corn syrup product was continuously produced in a two‐stage reactor system by pumping the feedstock through the glycoamylase reactor and then through the fungal α‐amylase reactor. Saccharide distributions at each stage were controllable to ±0.2%.