bluuebunny/crossref_metadata_2025_split huggingface dataset:
A CSTR‐hollow‐fiber system for continuous hydrolysis of proteins. Factors affecting long‐term stability of the reactor
Authors: Deeslie W. David , Cheryan Munir 
Published: December 2004

AbstractFactors affecting the long‐term operational stability of a CSTR‐hollow‐fiber reactor for continuous hydrolysis of proteins were studied. The activity declined in a stepwise manner during a run. Declining from 92% conversion to 60% conversion in about ten hours at a space time of four minutes. Initial decay appears to be due to leakage of small active fragments of the enzyme mixture (Pronase) through the membrane, and later decay due to thermal degradation and loss of activators such as calcium through the membrane. The rate of buildup of unconverted substrate in the reaction vessel was controlled by operational variables, but did not appear to affect the reactor output or the operation of the reactor. The decay of the reactor could be partially compensated for by appropriate manipulation of the space‐time variables.
Acid‐bacterial and ferric sulfate leaching of pyrite single crystals
Authors: Keller Ludwig , Murr L. E. 
Published: December 2004

AbstractPyrite single‐crystal cubes were cut, polished. and x‐rayed to produce orientations of (100), (110), (111), and (112). These crystallographically developed surfaces then were prepared to expose an area of 1 cm2, and the remainder of the crystal was coated with an acid‐resistant silicone cement. Crystals with representative orientations then were leached in ferric sulfate solutions adjusted to a pH of 2.3 with H2SO4 containing up to 6 × 103 ppm of Fe3+ at 30 and 55°C. Leaching was also conducted in acid‐bacterial lixiviants containing Thiobacillus ferrooxidans at 30°C and a thermophilic microorganism at 55°C. Surface corrosion and pitting associated with pyrite leaching were examined by scanning electron microscopy. Pyrite leaching in ferric sulfate solutions was observed to be different when compared to acid‐bacterial leaching. Ferric sulfate leaching required nearly 2 × 103 ppm of Fe3+ at 30°C while acid‐bacterial leaching at 30°C occurred without additions of Fe3+, and values of Fe3+ never exceeded 102 ppm. Because of precipitate formation, an accurate assessment of the role of crystallographic orientation on the leaching of pyrite is difficult.
Immobilization of glucose oxidase on sepharose by UV‐initiated graft copolymerization
Authors: D'angiuro L. , Cremonesi P. 
Published: December 2004

AbstractThe performance of a new method of enzyme immobilization based on photochemically initiated direct graft copolymerization was recently investigated. The immobilization reaction can be carried out in a simple way and by carefully selecting the reaction conditions, the enzyme‐graft copolymer can be obtained as the main reaction product. Coupling efficiency of glucose oxidase has been found to depend only on the amount of photocatalyst (FeCl3) fixed on Sepharose used as polysaccharide support. Small quantities of glycidymethacrylate (GMA) (0.25 g/g dry Sepharose) are sufficient but necessary to achieve the best enzyme coupling efficiency (20–40%). Enzyme immobilization occurs very rapidly and the entire reaction occurs within 60 min. Reaction patterns and physicochemical characteristics of the obtained enzyme‐graft copolymers exclude the glucose oxidase entrapment: therefore a covalent attachment mechanism may be proposed. The kinetic parameters of immobilized glucose oxidase (Km′ = 2.0 × 10−2M) are quite similar to those of free enzyme (Km = 1.93 × 10−2M), and no diffusion limitation phenomena are evidenced in samples having different enzyme or polymer content. Lyophilization, thermostability, and long‐term continuous operation also have been investigated. The advantages of this method over that using vinylenzyme copolymerization are discussed.
A study of acetic acid production by immobilized Acetobacter Cells: Oxygen transfer
Authors: Ghommidh C. , Navarro J. M. , Durand G. 
Published: December 2004

AbstractThe immobilization of living Acetobacter cells by adsorption onto a large‐surface‐area ceramic support was studied in a pulsed flow reactor. The high oxygen transfer capability of the reactor enabled acetic acid production rates up to 10.4 g L−1 h−1 to be achieved. Using a simple mathematical model incorporating both internal and external mass transfer coefficients, it was shown that oxygen transfer in the microbial film controls the reactor productivity.
Predominant role of hydrocarbon solubilization in the microbial uptake of hydrocarbons
Authors: Reddy P. G. , Singh H. D. , Roy P. K. , Baruah J. N. 
Published: December 2004

AbstractUsing EDTA and proteolytic enzymes to suppress hydrocarbon solubilization, direct evidence is presented in support of the mechanism of liquid hydrocarbon uptake by microbial cells predominantly from the solubilized or accommodated substrate. EDTA (2–5mM) strongly inhibited growth of three yeast species and one bacterial species on n‐hexadecane and the inhibition was removed by surfactant‐emulsified and surfactant‐solubilized alkane and also by excess addition of Ca2+. EDTA had no inhibitory effect on the growth of the organisms on soluble substrates such as sodium acetate and nutrient broth or on n‐pentane, a volatile alkane which was primarily transported by diffusion from gas phase. EDTA was shown to have no significant effect on the adsorption of cells on alkane drops. EDTA inhibition of growth was considered to be due to suppression of alkane solubilization, brought about by the solubilizing factor(s) produced by cells. It was shown that this chelating agent did not inhibit the growth of yeast on solubilized alkane but strongly inhibited its growth on alkane drops. It was demonstrated that adherent capacity of microbial cell to oil phase was closely related to the state of hydrocarbon emulsification and had no relationship to the ability of organisms to grow on hydrocarbon. Certain proteolytic enzymes inhibited the growth of yeast on alkane, presumably by digesting the alkane solubilizing protein, but not on glucose, and the inhibition was removed by a supply of surfactant‐emulsified and surfactant‐solubilized alkane. Specific solubilization of various hydrocarbon types during growth of the prokaryotic bacterial strain was demonstrated. The specific solubilization of hydrocarbon was strongly inhibited strain was demonstrated. The specific solubilization of hydrocarbon was strongly inhibited by EDTA, and the inhibition was removed by excess Ca2+. It was concluded that specific solubilization of hydrocarbons is an important mechanism in the microbial uptake of hydrocarbons.
Studies on the characteristics of alginate gels in relation to their use in separation and immobilized applications
Authors: Kierstan M. , Darcy G. , Reilly J. 
Published: December 2004

AbstractStudies on diffusion of NAD and hemoglobin from calcium and barium gels are reported where alginate grade, concentration, and gel dimensions were varied. These show that NAD diffusion characteristics are unaffected by alginate and ion concentrations; however, hemoglobin diffusion is affected by alginate concentration. Both hemoglobin and NAD diffusion patterns were shown to be affected by alginate gel dimensions. Studies are reported that show that polymannuronic alginate gels posses good porosity characteristics while polyguluronic alginates from gels with lower porosity, specifically with respect to high‐molecular‐weight compounds. These findings are discussed with the view to the use of alginate gels for immobilization, solids separation, and diffusion chromatography techniques.
Effects of ethanol and other alkanols on the kinetics and the activation parameters of thermal death in Saccharomyces cerevisiae
Authors: Leão Cecília , Van Uden N. 
Published: December 2004

AbstractEthanol, isopropanol, propanol, and butanol enhanced thermal death in Saccharomyces cerevisiae by increasing ΔS‡, the entropy of activation of thermal death while ΔH‡, the enthalpy of activation, was not significantly affected. The relation between ΔS‡ and alkanol concentration was linear with a different slope for each alkanol: ΔS‡X = ΔS‡0 + CAEX, where X is the alkanol concentration and CAE the entropy coefficient for the aqueous phase defined as increase in entropy of activation per unit concentrations of the alkanol. CAE was correlated with the lipid‐buffer partition coefficients of the alkanols while CME, the entropy coefficient for the lipid phase, was nearly identical for the four alkanol and averaged 37.6 entropy units per mole of alkanol per kilogram of membrane. As predicted by these results, the specific death rates (Kd) at constant temperature were an exponential function of the alkanol concentration and behaved in agreement with the following equation: In KXd = In K0d + (CAE/R)X, where R is the gas constant. It was concluded that the alkanols enhanced thermal death through nonspecific action on membrane structure.
Fungal treatment of mechanical pulps—its effect on paper properties
Authors: Pilon L. , Barbe M. C. , Desrochers M. , Jurasek L. , Neumann P. J. 
Published: December 2004

AbstractRefiner mechanical pulp was biologically treated with several higher fungi in order to test their potential for increasing the strength of paper. It was among the white‐rot fungi that the best results were obtained. Polyporus versicolor gave the best overall improvement in handsheet properties with no reduction in tear. The strength improvement is due to attack on lignin and to an increase in fiber flexibility as measured by water retention values and by acidic group content of the treated pulps. The brown‐rot fungi had a detrimental effect on paper properties.
Activated sludge system design for large variations or organic loading
Authors: Vasiliev V. B. , Vavilin V. A. 
Published: December 2004

AbstractAn aeration tank/sedimentation tank system is considered for large variations of organic loading. In this case, it is important to take into account the variability of the characteristics describing the oxidation of activated sludge as well as its sedimentation. The minimum cost of the treatment system is also evaluated.
Sorption of Talaromyces emersonii cellulase on cellulosic substrates
Authors: Moloney Aidan , Coughlan Michael P. 
Published: December 2004

AbstractThe sorption characteristics of the cellulase system of Talaromyces emersonii on various cellulosic substrates were examined. Analysis of reaction mixture supernatants by electrophoresis and enzyme assay showed that all components of the cellulase system were rapidly adsorbed by cellulose and then gradually returned to the liquid phase as the hydrolysis of the substrate progressed. The extent of adsorption in the rapid phase was influenced by pH, temperature, the nature of the substrate, and its concentration.
Isolation and functional characterization of hydrocarbon emulsifying and solubilizing factors produced by a Pseudomonas species
Authors: Reddy P. G. , Singh H. D. , Pathak M. G. , Bhagat S. D. , Baruah J. N. 
Published: December 2004

AbstractPseudomonas PG‐1 cultivated on pristane produced in good amount a heat‐stable polymeric substance which showed strong hydrocarbon emulsifying and solubilizing properties. The substance was isolated in crude form and was found to contain 34% protein, 16% carbohydrate, and 40% lipid. The hydrocarbon solubilizing activity of the isolate was strongly inhibited by EDTA but the chelating agent had no effect on the hydrocarbon emulsifying activity. Both activities of the isolate were strongly inhibited by chymotrypsin treatment indicating the importance of the protein moiety for its activity. Hydrocarbon solubilization by the isolate showed a certain degree of specificity to pristane in modest agitation generally used in microbial cultivation, but this specificity was lost by vigorous agitation in a Waring blender. It was proposed that in the first case, solubilization was effected by a solubilizing factor specific to pristane, whereas in the latter case, nonspecific solubilization occurred due to the action of the emulsifying factor. The rate of pristane solubilization by heat‐treated culture broth under the conditions of agitation used in cultivation (rotary shaker, 120 rpm) was found to be ca. 750 mg L−1 h−1 which was much larger than the maximal pristane uptake rate of 170 mg L−1 h−1 observed during microbial growth on the substrate. It was concluded that hydrocarbon solubilization could satisfactorily account for the substrate uptake and growth.
A kinetic model of starch hydrolysis by α‐ and β‐amylase during mashing
Authors: Marc A. , Engasser J. M. , Moll M. , Flayeux R. 
Published: December 2004

AbstractKinetics of malt starch hydrolysis by endogeneous α‐ and β‐amylases has been experimentally investigated in laboratory‐, pilot‐ and industrial‐scale reactors. The production rates of glucose, maltose, maltotriose and total extract, and the separate α‐ and β‐amylases deactivation rates are measured at varying mashing temperature and different initial starch concentrations and qualities. Based on the experimental results, a model is proposed that takes into account the initial carbohydrates and enzymes dissolution, the starch gelatinization, the separate hydrolytic action of α‐and β‐amylases on insoluble and soluble starch and dextrins, and the influence of temperature both on enzyme activities and thermal denaturation rate. The model can predict, at the three scales, the final sugars concentrations in the wort for given initial malt concentrations and enzymatic contents, and for a fixed temperature profile during the mashing process.
Characterization of cellobiose fermentations to ethanol by yeasts
Authors: Freer S. N. , Detroy R. W. 
Published: December 2004

AbstractTwenty‐two different yeasts were screened for their ability to ferment both glucose and cellobiose. The fermentation characteristics of Candida lusitaniae (NRRL Y‐5394) and C. wickerhamii (NRRL Y‐2563) were selected for further study because their initial rate of ethanol production from cellobiose was faster than the other test cultures. C. lusitaniae produced 44 g/L ethanol from 90 g/L cellobiose after 5–7 days. When higher carbohydrate concentrations were employed, fermentation ceased when the ethanol concentration reached 45–60 g/L. C. lusitaniae exhibited barely detectable levels of β‐glucosidase, even though the culture actively fermented cellobiose. C. wickerhamii produced ethanol from cellobiose at a rate equivalent to C. lusitaniae; however, once the ethanol concentration reached 20 g/L, fermentation ceased. Using p‐nitrophenyl‐β‐D‐glucopyranoside (pNPG) as substrate, β‐glucosidase (3–5 U/mL) was detected when C. wickerhamii was grown anaerobically on glucose or cellobiose. About 35% of the β‐glucosidase activity was excreted into the medium. The cell‐associated activity was highest against pNPG and salicin. Approximately 100‐fold less activity was detected with cellobiose as substrate. When empolying these organisms in a simultaneous saccharification‐fermentation of avicel, using Trichoderma reesei cellulase as the saccharifying agent, 10–30% more ethanol was produced by the two yeasts capable of fermenting cellobiose than by the control, Saccharomyces cerevisiae.
Estimation of true growth and product yields in aerobic cultures
Authors: Oner M. D. , Erickson L. E. , Yang S. S. 
Published: December 2004

AbstractIn the microbial production of useful products, it is important to understand the allocation of substrate energy for maintanance, growth, and product formation. Methods are presented to obtain point and 95% confidence interval estimates for the true growth yield parameter, true product yield parameter, and the maintenance parameter. Methods are presented which allow all data to be used simultaneously for those cases where more than the minimum number of measurements are made at each specific growth rate (or dilution rate). Three estimation methods and two forms of the energy allocation equations are investigated. Point estimates are similar for the three methods, but interval estimates are considerably larger for one of the three methods. The results depend on the form of the equations.
Preparative separation of α‐ and β‐naphthols catalyzed by immobilized sulfatase
Authors: Pelsy Gilles , Klibanov Alexander M. 
Published: December 2004

AbstractIt has been found that sulfatase from Helix pomatia hydrolyzes β‐naphthyl sulfate much faster than α‐naphthyl sulfate; e.g., at pH 7.8, while the former is readily hydrolyzed, the latter undergoes no appreciable hydrolysis. Kinetic investigations of both enzymatic and acid hydrolysis of naphthyl sulfates and their analogs indicate that in the enzymatic reaction the difference in reactivities is due to steric hindrances exerted in α‐naphthyl sulfate by the benzene ring adjacent to the one bearing the sulfate group. (In the β‐ester this ring is remote from the site of hydrolysis.) The enzyme was immobilized and employed for the preparative resolution of α‐ and β‐naphthols: a mixture of the isomers was first sulfated with chlorosulfonic acid and then incubated with sulfatase covalently attached to alumina. The β‐naphthol produced was extracted with benzene, followed by acid hydrolysis of α‐naphthyl sulfate in the remaining aqueous solution and extraction of the α‐naphthol formed. Helix pomatia sulfatase also expresses a marked regiospecificity in the hydrolysis of ortho and para substituted phenyl sulfates. Therefore, the enzyme can be used for the preparative separation of naphthols as well as a variety of isomeric phenols.
Structure‐function relationships in immobilized chymotrypsin catalysis
Authors: Clark Douglas S. , Bailey James E. 
Published: December 2004

AbstractSpecific activities and the amounts of active immobilized enzyme were determined for several different preparations of α‐chymotrypsin immobilized on CNBr‐activated Sepharose 4B. Electron paramagnetic resonance (EPR) spectroscopy of free and immobilized enzyme with a spin label coupled to the active site was used to probe the effects of different immobilization conditions on the immobilized enzyme active site configuration. Specific activity of active enzyme decreased and rotational correlation time of the spin label increased with increasing immobilized enzyme loading. Enzyme immobilized using an intermediate six‐carbon spacer arm exhibited greater specific activity and spin label mobility than directly coupled enzyme. The observed activity changes due to immobilization were completely consistent with corresponding active site structure alterations revealed by EPR spectroscopy.
Immobilization of the exo‐maltohexaohydrolase by the irradiation method
Authors: Nakakuki Teruo , Hayashi Toru , Monma Mitsuru , Kawashima Koji , Kainuma Keiji 
Published: December 2004

AbstractExomaltohexaohydrolase (E.C.3.2.1.98) was immobilized by radiocopolymerization of some synthetic monomers which were mixed in various combinations. Irradiation was carried out while the mixture of monomers and enzymes was frozen in petroleum ether–dry‐ice bath. Recovery of the immobilized enzyme was 44–75%.The optimum pH of the enzyme slightly shifted to the acidic side. The pH stability was improved remarkably by immobilization. The enzyme was stable retaining more than 90% of its original activity in the range pH 4–11. The optimum reaction temperature of the enzyme increased about 2°C. Heat stability was also improved by immobilization, and that the enzyme retained about 40% of its original activity after treatment at 75°C for 15 min. The immobilized enzyme was stable to the repeated use of 20 cycles. The Km value of the enzyme for short‐chain amylose was almost the same as that of native enzyme. When soluble starch was used as the substrate, the Km, value of the enzyme was three times as large as that of native enzyme. Effects of various metal ions and inhibitors on the immobilized enzyme were also studied compared to the native enzyme.
Fermentation air filtration upgrading by use of membrane cartridge filters
Authors: Bruno C. F. , Szabo Louis A. 
Published: December 2004

AbstractThe evolution of the use of improved, hydrophobic air filters in industrial plant germinators and fermentors is described, with the improved filters replacing Fiberglas media. The history and problems associated with use of Fiberglas media are described, as are the advantages of the hydrophobic filter.
Anaerobic filters for the treatment of coal gasification wastewater
Authors: Suidan Makram T. , Siekerka Gerald L. , Kao Shu‐Wen , Pfeffer John T. 
Published: December 2004

AbstractA process train consisting of the following sequence of unit processes, a berl‐saddle‐packed anaerobic filter, an expanded bed, granular activated carbon anaerobic filter, and an activated sludge nitrification system was evaluated for the treatment of a synthetically prepared coal gasification wastewater. The first‐stage anaerobic filter resulted in very little removal of organic matter and no methane production. Excellent reduction in organic matter occurred in the granular activated carbon anaerobic filter. The removal mechanism was initially adsorptive and near the end of the study, removal of organic matter was primarily through conversion to methane gas. It is felt that the success of the activated carbon anaerobic filter was due to the ability of the activated carbon to sequester some components of the wastewater that were toxic to the mixed culture of anaerobic microorganisms. The activated sludge nitrification system resulted in complete ammonia oxidation and was very efficient in final effluent polishing.
Effects of the inability of suspension‐feeding protozoa to collect all cell sizes of a bacterial population
Authors: Pavlou Stavros , Fredrickson A. G. 
Published: December 2004

AbstractThe effects of the inability of suspension‐feeding protozoa to collect bacteria over the whole range of sizes in the bacterial size distribution were examined by constructing mathematical models based on this assumption. Systems of suspension‐feeding protozoa grown on both growing and nongrowing bacteria were examined in both batch and continuous culture. The models were able to predict three experimental observations common in such systems. Some additional features of the systems which should be useful in interpreting results of experiments with suspension feeding protozoa and in designing new experiments were predicted, also.
Removal of color from kraft mill wastewaters with cultures of white‐rot fungi and with immobilized mycelium of Coriolus versicolor
Authors: Livernoche D. , Jurasek L. , Desrochers M. , Dorica J. , Veliky I. A. 
Published: December 2004

AbstractScreening fifteen strains of white‐rot fungi for their ability to decolorize combined bleached kraft effluent showed that Coriolus versicolor in liquid culture removed over 60% of the color of the effluent within six days in the presence of sucrose. Treatment of the same effluent with this fungus, immobilized in beads of calcium alginate gel, resulted in 80% decolorization after three days in the presence of sucrose. Caustic extraction E1 effluent was also decolorized by the immobilized fungus. Decolorization was achieved more rapidly at pH 5.0 than at pH 7.0. Recycled beads could remove color efficiently and repeatedly in the presence of air but not under anaerobic conditions.