bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dephenolization of industrial wastewaters catalyzed by polyphenol oxidase
Authors: Atlow Stuart C. , Bonadonna‐Aparo Lucia , Klibanov Alexander M. 
Published: December 2004

AbstractA new enzymatic method for the removal of phenols from industrial aqueous effluents has been developed. The method uses the enzyme polyphenol oxidase which oxidizes phenols to the corresponding o‐quinones; the latter then undergo a nonenzymatic polymerization to form water‐insoluble aggregates. Therefore, the enzyme in effect precipitates phenols from water. Polyphenol oxidase has been found to nearly completely dephenolize solutions of phenol in the concentration range from 0.01 to 1.0 g/L. The enzymatic treatment is effective over a wide range of pH and temperature; a crude preparation of polyphenol oxidase (mushroom extract) is as effective as a purified, commercially obtained version. In addition to phenol itself, polyphenol oxidase is capable of precipitating from water a number of substituted phenols (cresols, chlorophenols, naphthol, etc.). Also, even pollutants which are unreactive towards polyphenol oxidase can be enzymatically coprecipitated with phenol. The polyphenol oxidase treatment has been successfully used to dephenolize two different real industrial waste‐water samples, from a plant producing triarylphosphates and from a coke plant. The advantage of the polyphenol oxidase dephenolization over the peroxidase‐catalyzed one previously elaborated by the authors is that the former enzyme uses molecular oxygen instead of costly hydrogen peroxide (used by peroxidase) as an oxidant.
Use of catalase from Escherichia coli in model experiments for oxygen supply of microorganisms with hydrogen peroxide
Authors: Nies D. , Schlegel H. G. 
Published: December 2004

AbstractA catalase has been purified from aerobically grown Escherichia coli K12. The enzyme exhibits unorthodox properties compared with catalyse from bovine liver and seems to be identical to hydroperoxidase II from E. coli. A mathematical model is presented which makes it possible to calculate the steady‐state concentration of hydrogen peroxide in an open system. The model has been verified experimentally. It has been shown that the catalase from E. coli is better suited than the bovine liver enzyme for oxygen supply to cell suspensions using hydrogen peroxide.
The HCH‐1 model of enzymatic cellulose hydrolysis
Authors: Holtzapple Mark T. , Caram Hugo S. , Humphrey Arthur E. 
Published: December 2004

AbstractSolka Floc BW200 was enzymatically hydrolyzed in a batch reactor using a commercial cellulase preparation. A total of 50 different hydrolysis conditions were run within a 10‐fold range in enzyme concentration and a 30‐fold range in cellulose concentration. The data were evaluated in three ways using five different models. Previous literature models were not as successful in correlating the data as the HCH‐1 Model derived in this work.
Effect of ferric tartrate/sodium hydroxide solvent pretreatment on enzyme hydrolysis of cellulose in corn residue
Authors: Hamilton T. J. , Dale B. E. , Ladisch M. R. , Tsao G. T. 
Published: December 2004

AbstractLignocellulose containing 62% cellulose was prepared from corn residue by dilute acid hydrolysis using 5% H2SO4at 90°C. The lignocellulose was then treated with a cellulose solvent consisting of a ferric sodium tartrate complex in 1.5Nsodium hydroxide at levels ranging from 4:1 to 12:1 (solvent volume: corn residue lignocellulose) or a 1.5Nsodium hydroxide solution alone. Subsequent hydrolysis with cellulase enzymes fromTrichoderma reeseigave cellulose conversions which were two to three times higher than untreated lignocellulose (30%) and approached 90% conversion after 24 h in the best cases. It was found that increasing cellulase enzyme levels from 3.74 lU/g lignocellulose to 7.71 lU/g lignocellulose increased cellulose conversion by 50% at all pretreatment conditions, while an increase from 7.71 to 10.1 lU/g gave only an additional 5–10% increase. Pretreatment with sodium hydroxide resulted in 5–25% lower conversions than observed for cellulose treated with the solvent, depending on enzyme levels and treatment levels. At high enzyme levels, sodium hydroxide pretreatment is almost as effective in enhancing cellulose conversion after 24 h as is pretreatment using the cellulose solvent.
Acidogenic and methanogenic fermentation of causticized straw
Authors: Baccay Romeo A. , Hashimoto Andrew G. 
Published: December 2004

AbstractThe effects of pretreatment process variables [straw concentration between 20 and 90 kg volatile solids (VS)/m3, temperature between 30 and 85°C, and alkaline dosage between 0 and 80 g NaOH/kg VS] on acidogenesis and methanogenesis were investigated. Rates of acidogenesis and methanogenesis were determined using firstorder kinetics, and ultimate acid and methane yields were measured. The acid yield was not affected by pretreatment concentration or temperature, but increased as alkaline dosage increased. The acidogenesis rate was not affected by pretreatment temperature or alkaline dosage, but decreased as the substrate concentration increased. This decrease in the acidogenesis rate was attributed to a decrease in the inoculum: substrate ratio as the substrate concentration increased. The methane yield and methanogenesis rate were not affected by pretreatment substrate concentration or temperature, and both increased with alkaline dosage up to about 40 g NaOH/kg VS, then remained relatively constant above 40 g NaOH/kg VS.
Cellulose degradation and monitoring of viscosity decrease in cultures of Cellulomonas uda grown on printed newspaper
Authors: Rapp Peter , Reng Hansgeorg , Hempel Dietmar‐Christian , Wagner Fritz 
Published: December 2004

AbstractThe rheological behavior of cultures of Cellulomonas uda with shredded printed newspaper as the carbon source was studied. The initial substrate concentrations ranged from 23 to 60 g/L. The changes in apparent viscosity were followed on‐line by applying a commercially available process viscometer and discretely using a rotational viscometer with an anchor impeller. During the time of highest cellulose degradation, the broths exhibited a pseudoplastic behavior which could be explained satisfactorily by the power‐law model. At the end of cultivation when cellulose degradation slowed down, the broths became Newtonian in behavior. Endo‐1,4‐β‐glucanase, 1,4‐β‐xylanase, β‐glucosidase, and β‐xylosidase activities were also determined during cultivation as well as cellulose degradation and cell mass production. The beginning of endoglucanase formation and the start of the final viscosity decrease of the bacterial paper pulp suspensions could be correlated.
Enzymatic hydrolysis of cellulosic materials: A kinetic study
Authors: Beltrame Pier Luigi , Carniti Paolo , Focher Bonaventura , Marzetti Annamaria , Sarto Virginio 
Published: December 2004

AbstractA kinetic study of the enzymatic hydrolysis of two celluloses with different structural features was performed at various temperatures (26–50°C). The enzymatic system consisted of three types of enzymes: E1—β‐1,4‐glucan glucanohydrolase; E2—β‐1,4‐glucan cellobiohydrolase; and E3—β‐glucosidase. A mathematical model for the mechanism of the hydrolysis of cellulosic materials catalyzed by a multienzymatic system was checked and a good rationalization of the experimental results was achieved. Uncompetitive and competitive glucose inhibition on E1 and E2, respectively, appeared to occur for both substrates. Inhibition by cellobiose was checked at 34°C on one substrate. The Vmax, Km, and glucose inhibition constants were optimized and their dependence on temperature determined.
A simple algorithm for on‐line prediction of BOD5 by a microprocessor‐based system
Authors: Raviv Roni , Ben‐Yaakov Sam 
Published: December 2004

AbstractA novel algorithm for predicting BOD5 from the dissolved oxygen (DO) concentration after a relatively short incubation period is presented and evaluated experimentally. Test runs on synthetic and experimentally derived raw data suggest that BOD5 can be predicted to within 15% ca. 36 h. The method can be improved by filtering out, via a digital filter, noise from the raw data. The suggested algorithm does not require elaborate computations or large data storage and can therefore be implemented on a low‐cost microcomputer for fast on‐line determination of BOD5.
Spectral shifting by dyes to enhance algae growth
Authors: Prokop A. , Quinn M. F. , Fekri M. , Murad M. , Ahmed S. A. 
Published: December 2004

AbstractThe photosynthetic growth action spectrum of a green alga at three bands of visible light (blue, orange, and red) at fixed quanta input and under light‐limiting conditions was measured in a batch cultivation system. Quantum efficiencies (biomass dry weight increment per quanta absorbed) were better in the yellow–red region than in the blue region. Results served as a basis for the design and optimization of a dye system that would shift the energy of solar radiation to the required wavelength range by absorbing ultraviolet to blue radiation and emitting in the yellow–red, thus enhancing algae growth. Direct incorporation of dyes into the growth medium, although theoretically expected to enhance growth, in fact resulted in dye decomposition, toxicity to algae and consequently in growth inhibition. Indirect application of dyes in a double tubular reactor (algae inside and dye solution outside) demonstrated growth enhancement for certain dyes with high quantum yields and stability, which had suitable absorption/emission spectra for artificial light sources used. The maximum indirect growth enhancement was obtained using rhodamine 6G at a concentration of 3×10−5M with tungsten filament lamp sources.
Stimulation of hydrogen photoproduction in algae by removal of oxygen by reagents that combine reversibly with oxygen
Authors: Rosenkrans Addison M. , Krasna Alvin I. 
Published: December 2004

AbstractHydrogen photoproduction from water by Scenedesmus cells was achieved in the presence of reagents that combine reversibly with oxygen. The oxygen can be subsequently released, and H2 and O2 are obtained in the 2:1 ratio expected for H2O photolysis. This was accomplished in an experimental design which facilitates rapid transfer of gases and the use of a variety of water‐soluble and DMSO‐soluble chelates of cobalt which combine reversibly with oxygen.
The growth dynamics of a methanol‐utilizing bacterium L3 in a batch bioreactor
Authors: Agrawal Pramod , Lim Henry C. 
Published: December 2004

AbstractThe growth dynamics of a methanol utilizing bacterium, L3, in batch bioreactors were experimentally investigated. Formaldehyde, a key intermediate of methanol oxidation, is indicated to have a significant role in the complex batch growth behavior of L3. The intricate batch growth dynamics of many microorganisms can be elegantly characterized by examining the specific rates of exchange of nutrients and products between the cells and the cellular environment. Following such an analysis, the batch growth of L3 on methanol was characterized by the presence of unbalanced and balanced growth phases. The nature and significance of nutrient and product concentration profiles or semilog‐arithmic profiles of nutrient and product exchange rates during balanced and unbalanced growth phases are also outlined.
The impulse response of Chlamydomonas reinhardii in nitrite‐limited chemostat culture
Authors: Cunningham Alexander 
Published: December 2004

AbstractThis article presents a clear experimental determination of the behavior of nutrient uptake rate, mean cell nutrient content, and specific growth rate following the injection of pulses of additional limiting nutrient into a chemostat culture of Chlamydomonas reinhardii. The uptake rate per cell is a hyperbolic function of external nutrient concentration. The specific growth rate is related to the mean cell nutrient content by a hysteresis loop. The data obtained is used to test the performance of the Caperon–Droop mean cell quota model. It is demonstrated that this model cannot be used under severe transient conditions, even when modified by the introduction of a discrete time delay, a simple memory function, or time‐dependent intracellular nutrient processing.
Comparison of different strategies for the lipase‐catalyzed preparative resolution of racemic acids and alcohols: Asymmetric hydrolysis, esterification, and transesterification
Authors: Cambou Bernard , Klibanov Alexander M. 
Published: December 2004

AbstractLipase from Candida cylindracea has been found to be a highly stereospecific catalyst suitable for preparative resolution of racemic acids and alcohols. Using (R, S)−2‐(p‐chlorophenoxy) propionic acid (whose R isomer is a herbicide) and (R, S)‐sec‐butanol (a versatile synthon) as model compounds, three alternative approaches to lipase‐catalyzed resolutions—asymmetric hydrolysis, esterification, and transesterification—have been compared. Enzymatic esterification in biphasic systems has been ruled out for preparative resolutions because addition of the acids lowers the pH of the aqueous phase thereby greatly reducing the efficiency of the procedure. Both enzymatic hydrolysis and biphasic transesterification afforded resolution of the racemates on a gram scale. From the standpoint of productivity, ease of product separation, and the amount of steps required, lipasecatalyzed asymmetric hydrolysis has been judged to be superior for the practical resolution of racemic acids, and lipase‐catalyzed asymmetric transesterification to be the method of choice for the practical resolution of racemic alcohols.
The kinetics and physiology of stipitatic acid and gluconate production by carbon sufficient cultures of Penicillium stipitatum growing in continuous culture
Authors: Linton J. D. , Austin R. M. , Haugh D. E. 
Published: December 2004

AbstractThe yield from glucose of ammonia‐grown carbon‐limited continuous cultures of Penicillium stipitatum was ca. 20% higher than that of nitrate‐grown cultures at all growth rates examined. However, the yield from oxygen was similar during growth on both nitrogen sources. Under phosphate limitation the specific rate of gluconic acid and stipitatic acid production increased with growth rate, but the former product accounted for virtually 100% of the excreted carbon. Stipitatic acid was not produced under nitrogen limitation, and glucose supplied to the culture in excess of that required for growth was virtually quantatively converted into gluconic acid. Productivities of 11.4 g gluconic acid/L/h were stably maintained in continuous culture. Under conditions of glucose excess the enzyme glucose oxidase was excreted into the culture. The specific activity of this extracellular enzyme increased when the input glucose concentration to the culture was progressively increased. The excretion of a protein under nitrogen limitation suggests that this enzyme plays an important role under these conditions. Indeed, it was demonstrated that nitrogen‐limited cultures did not overmetabolize gluconate at either pH 6.5 or 3.5, although up to 29 g/L gluconate was present in the culture. The Ygluconate and YO2 of C‐ and N‐limited gluconate‐grown cultures were similar indicating that the rapid conversion of glucose to gluconate probably affords a means of regulating carbon flow in this organism. Nitrogen‐limited cultures of P. stipitatum overmetabolized glucose to a much greater extent than acetate, fructose, or gluconate.
Optimization of solid substrate fermentation of wheat straw
Authors: Abdullah A. L. , Tengerdy R. P. , Murphy V. G. 
Published: December 2004

AbstractOptimal conditions for solid substrate fermentation of wheat straw with Chaetomium cellulolyticum in laboratory‐scale stationary layer fermenters were developed. The best pretreatment for wheat straw was ammonia freeze explosion, followed by steam treatment, alkali treatment, and simple autoclaving. The optimal fermentation conditions were 80% (w/w) moisture content; incubation temperature of 37°C; 2% (w/w) unwashed mycelial inoculum; aeration at 0.12 L/h/g; substrate thickness of 1 to 2 cm; and duration of three days. Technical parameters for this optimized fermentation were: degree of substance utilization, 27.2%; protein yield/substrate, 0.09 g; biomass yield/bioconverted substrate, 0.40 g; degree of bioconversion of total available sugars in the substrate, 60.5%; specific efficiency of bioconversion, 70.8%; and overall efficiency of biomass production from substrate, 42.7%. Mixed culturing of Candida utilis further increased biomass production by 20%. The best mode of fermentation was a semicontinuous fed‐batch fermentation where one‐half of the fermented material was removed at three‐day intervals and replaced by fresh substrate. In this mode, protein production was 20% higher than in batch mode, protein productivity was maintained over 12 days, and sporulation was prevented.
Kinetic characteristics of biochemical cyclic reaction systems: Amplification of substrate cycle system
Authors: Okamoto Masahiro , Hayashi Katsuya 
Published: December 2004

AbstractThe amplification of a substrate cycle system with reversible closed reaction of two substrates was represented by mathematical equations. The results are summarized as follows: the amplification was affected especially by the affinity of enzyme and substrate, by the rate constant in rate‐limiting reaction step, and by the saturation degree of enzyme by substrate. These amplifications were not simply determined by the values of Km and Vmax, because each rate parameter in the system can affect the degree of amplification independently. The conclusion is that the “apparent” equilibrium constant of this system cannot be uniquely estimated from only data of Km and Vmax even if the reaction occurs in a closed system.
A segregated model for plasmid content and product synthesis in unstable binary fission recombinant organisms
Authors: Seo Jin‐Ho , Bailey James E. 
Published: December 2004

AbstractPlasmid propagation in populations of unstable, binary fission recombinant organisms has been studied using a segregated, population balance mathematical model. Segregated models have the advantage of direct incorporation of basic information on mechanisms and kinetics of plasmid replication and segregation at the single‐cell level. The distribution of cellular plasmid content and specific rates of plasmid gene expression have been obtained for several single‐cell models of plasmid replication, partition, and gene expression. Plasmid replication kinetics during cell growth significantly influence the plasmid content distribution. In the case of transient growth of plasmid‐containing and plasmid‐free cells in partially selective medium, the degree of selection required for stable maintenance of plasmid‐containing cells has been determined. Guidelines are presented for applicability of simpler, nonsegregated models and for evaluation of the parameters in these models based on single‐cell mechanisms and associated parameters.
Primary particle formation in protein precipitation
Authors: Nelson C. D. , Glatz C. E. 
Published: December 2004

AbstractRecovery of proteins frequently involves a precipitation step in which ease of recovery of the solid protein depends on the size and density of the solid particles. The solid particles are actually aggregates of much smaller primary particles. In this work, possible influences on the aggregates of primary particle properties are postulated. The role of precipitation conditions during precipitation of soy protein with acid or CaCl2 is determined by measurement of zeta potential and size distribution. Results are consistent with a nucleation/growth model for determination of size. There is indirect evidence that fractionation occurs at the primary particle level, although the particles are homogeneous at the aggregate level.
Profile control scheme in a Bakers' yeast fed‐batch culture
Authors: Takamatsu Takeichiro , Shioya Suteaki , Okada Yoshiki , Kanda Masaaki 
Published: December 2004

AbstractThis article develops and discusses a practical and useful computer control scheme so that the biomass concentration or the specific growth rate will as accurately as possible follow a desired profile specified in advance. Many computer simulations certified the validity of the proposed control scheme. The control scheme proposed, called “programmed‐controller/feedback‐compensator (PF) system,” consists of a programmed controller that will follow the desired profile unless there is noise or disturbance and a feedback compensator that will compensate the noise and correct error in the model parameters. As the feedback compensator, the model reference adaptive control (MRAC) algorithm was also proposed. The PF system with MRAC, named PF–MRAC, could be used sufficiently for the profile control of the specific growth rate. For the profile control of the cell concentration, “predictive control algorithm” should be added to the PF system, and the consequent control scheme was named as the PFP system. Many numerical examples showed that the PFP system with MRAC, named PFP–MRAC, proposed here worked sufficiently well.
The acetone butanol fermentation on glucose and xylose. I. Regulation and kinetics in batch cultures
Authors: Fond Olivier , Engasser Jean‐Marc , Matta‐El‐Amouri Ghassam , Petitdemange Henri 
Published: December 2004

AbstractThe kinetics in batch culture of the acetone butanol fermentation by Clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. The fastest initial growth and transition from an acid to a solvent metabolism occurs on glucose, with a final 62 g/L glucose conversion. On xylose, an initial slower growth rate and a longer metabolic transition result in higher cellular and acids concentration, thus in a level of fermented sugar limited to 47 g/L. Batch fermentations on mixtures of glucose and xylose show that both sugars can be fermented, with a higher rate for glucose. However, xylose fermentation is inducible and inhibited at glucose level above 15 g/L. Mixtures of glucose and xylose yield the highest amount of fermented sugars, up to 68 g/L, as a result of both a fast metabolic transition on glucose and a strong acid reconsumption on xylose. In all cases, solvent production is triggered at a total acid concentration between 4 and 5 g/L, whereas the final inhibition of the fermentation takes place at a total butanol and acid concentration between 18 and 20 g/L.
The release of fermentable carbohydrate from peat by steam explosion and its use in the microbial production of solvents
Authors: Forsberg Cecil W. , Schellhorn Herb E. , Gibbins L. N. , Maine Frank , Mason Eileen 
Published: December 2004

AbstractSteam treatment of peat at 200°C for 3 min, followed by instantaneous decompression (steam explosion), solubilized up to 28% of the dry matter. Seventy‐five percent of the solubilized material was carbohydrate, 33% of which was composed of mono‐ and disaccharides, including galactose, glucose, xylose, mannose, arabinose, and cellobiose, in order of decreasing concentration. The solubilized materials served as the sole source of carbohydrate for growth and solvent production by Clostridium acetobutylicum and C. butylicum which utilized up to 40% of the carbohydrate. Of the saccharides in this mixture, galactose was the least readily utilized. Approximately 30% of the fermentable carbohydrate used was converted to fatty acids and solvents, with the primary fermentation product being butyrate. Clostridium thermohydrosulfuricum was able to utilize ca. 50% of the carbohydrate, and simultaneously produced slightly more than 1 mol ethanol/mol saccharide metabolized. This organism, like other strains tested, used galactose less readily than the other sugars. The residue from the steam explosion process contained 24% cellulose, but it could not serve as a source of carbohydrate for the growth of either Bacteroides succinogenes or Clostridium thermocellum, suggesting that inhibitors were released during the steam treatment.