bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic flavor enhancement in food products: A commercial view
Authors: Marshall W. E. 
Published: December 2004

AbstractThis study illustrates approaches using botanical proteinases and a pancreatic lipase to improve the palatability of two types of food. A third example is presented to illustrate the use of a chelating agent in growing corn to increase the sugar content by over 50%, presumably by influencing enzyme activity in the corncob itself. The purpose is to show that one is not limited to using only the microbial approach for producing flavors but to point out the broader concept of food palatability which includes texture and flavor.
Pore diffusion model for a two‐substrate enzymatic reaction: Application to galactose oxidase immobilized on porous glass particles
Authors: Dahodwala S. K. , Humphrey A. E. , Weibel M. K. 
Published: December 2004

AbstractAn analysis of the pore diffusion model involving a two‐substrate enzymatic reaction is presented. The resulting equations have been applied to the case of galactose oxidase catalyzed oxidation of galactose when the enzyme is immobilized on porous glass particles. The physical constants of the system were obtained by theoretical predictions and the enzyme concentration in the porous medium was derived from the experimental results. The calculations were performed with the assumption that the kinetic parameters of the enzyme remain unchanged upon immobilization. The theoretically calculated effectiveness factors were compared with the experimental effectiveness factors determined from the batch kinetic experiments and were found to be in agreement. The results are presented as effectiveness factor plots graphed as functions of bulk galactose and oxygen concentrations. The model was extended in order to study the effect of external mass transfer coefficients and pore enzyme concentrations on the effectiveness factors.
Immobilization of a cephalosporin acetylesterase by containment within an ultrafiltration device
Authors: Abbott Bernard J. , Cerimele Benito , Fukuda David S. 
Published: December 2004

AbstractA cephalosporin acetylesterase produced by Bacillus subtilis catalyzes the deacetylation of 7‐aminocephalosporanic acid (7‐ACA). Previous reports from our laboratory described the kinetic constants that characterize the reaction: Km = 2.8 × 10−3M, Kia acetate = 5 × 10−2M, and Kid deacetyl‐7‐ACA = 3.6 × 10−2M. These constants were used to predict the time course of the reaction using the following equation for dual competitive product inhibition.

where St = mg/ml 7‐ACA, At = mg/ml acetate, Dt = mg/ml deacetyl‐7‐ACA. The predicted time course closely matched the time course measured experimentally. The equation also was solved without the inhibition terms and the solution indicated that product inhibition caused about a 30% increase in the time required for complete (>97%) hydrolysis of a 24 mg/ml 7‐ACA solution. The esterase was immobilized by containment within an ultrafiltration device. With this technique the enzyme was reused 20 times over an 11 day span to deacetylate 7‐ACA solutions containing 4 to 24 mg/ml 7‐ACA. The specific activity after the 20th use was the same as the activity prior to the first use, indicating little enzyme inactivation occurred.
Computer assistance in multiparameter flow microphotometry of mammalian cells
Authors: Stoehr Michael , Gebhardt Ulrich , Goerttler Klaus 
Published: December 2004

AbstractFlow system technology enables the biological and medical experimenter to investigate the distribution spectra of various cellular characteristics separately or in parameter combination on the basis of ultrarapid single cell measurements. A typical rate of recognition is about 1000 to 5000 cells per second and the precision of measurements and their statistical relevance has been previously unobtainable. According to the approach of the multiparameter analysis and high data rate, computer assistance in flow system technology is given primary consideration. In this study three different kinds of software controlled modes in data acquisition are demonstrated: normal acquisition and linear accumulation of single parameters, spectra accumulation of two correlated parameters of each single cell and documentation as linear, two‐ or three‐dimensional distribution pattern, and linear accumulation of two correlated parameters simultaneously with their actual signal‐to‐signal ratio. A first attempt to analyze distribution spectra was the application of the entropy of the structure routinely used in cybernetics. This function seems to be a measure for determining the degree of synchrony in an appropriate pretreated cell population. A special mathematical strategy has been applied to the linear spectra of cellular DNA content, whose advantage is the quantitative extraction of the fractions concerning the various phases of the life cycle cells. The validity of this special curve fitting procedure has been proven on various experimental cell populations.
Microbiological leaching of a chalcopyrite concentrate by Thiobacillus ferrooxidans
Authors: Sakaguchi Hiromichi , Silver Marvin , Torma Arpad E. 
Published: December 2004

AbstractThe microbiological leaching of a chalcopyrite concentrate has been investigated using a pure strain of Thiobacillus ferrooxidans. The optimum leaching conditions regarding pH, temperature, and pulp density were found to be 2.3, 35°C, and 22%, respectively. The energy of activation was calculated to be 16.7 kcal/mol. During these experiments the maximum rate of copper dissolution was about 215 mg/liters/hr and the final copper concentration was as high as 55 g/liter. This latter value is in the range of copper concentrations which may be used for direct electrorecovery of copper. Jarosite formation was observed during the leaching of the chalcopyrite concentrate. When the leach residue was reground to expose new substrate surface, subsequent leaching resulted in copper extractions up to about 80%. On the basis of this experimental work, a flow sheet has been proposed for commercial scale biohydrometallurgical treatment of high‐grade chalcopyrite materials.
Dual control of invertase Biosynthesis in chemostat culture
Authors: Toda K. 
Published: December 2004

AbstractIn a previous study on the chemostat culture of Saccharomyces carlsbergensis, maximum invertase specific activity was observed at an intermediate dilution rate. A possible regulation mechanism, assuming there are simultaneous effects of induction and repression on two sites of the operator loci for invertase formation, is proposed which might account for the observed curve of the dilution rate effect.
Continuous regeneration of NAD(P)+ by flavins covalently bound to sepharose
Authors: Månsson M. O. , Mattiasson B. , Gestrelius S. , Mosbach K. 
Published: December 2004

AbstractVarious flavins, FMN, FAD, and acriflavin, were immobilized to Sepharose using several different coupling methods. The only product stable enough to permit extended studies was acriflavin coupled to epoxy‐substituted Sepharose. The nonenzymic oxidizing capacity towards NAD(P)H was investigated and a 25% specific activity, compared to that of free acriflavin, was observed. The reduced acriflavin was immediately auto‐reoxidized in air and could thus be reused. It was shown that acriflavin‐Sepharose preparations function as NAD(P)H oxidizing agents in a number of different dehydrogenase systems including lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), malate dehydrogenase (MDH), alanine dehydrogenase (alaDH), and glutamate dehydrogenase (GDH). The amount of expensive coenzyme necessary for high product formation of such systems was thereby markedly reduced.
Kinetics of substrate removal in a completely mixed anaerobic filter
Authors: Dewalle F. B. , Chian E. S. K. 
Published: December 2004

AbstractA completely mixed anaerobic filter, in which the influent organic matter concentration is diluted with recirculated effluent, was found to effectively remove organic matter concentrations in high strength acidic wastewater, at a range of organic loadings and shock loads. Increases in organic loading had a substantial effect on the relative organic matter composition of the effluent and the magnitude of the fatty acid fraction showed a pattern inverse to that of the nitrogenous organics. A fixed film model was formulated which indicated that at high substrate concentrations the substrate removal rate is proportional to the square root of the substrate concentration and the specific area of the filter medium. A comparison of the biofilm model and the measured effluent concentrations tended to indicate that the substrate removal rate is primarily affected by substrate concentration, specific surface area, flow rate, and temperature of the unit.
Characteristics of hydrocarbon uptake in cultures with two liquid phases
Authors: Nakahara T. , Erickson L. E. , Gutierrez J. R. 
Published: December 2004

AbstractIn hydrocarbon fermentation, the efficiency of hydrocarbon uptake by cells ins one of the keys to the economical production of single‐cell protein. This work is concerned with characterization of cultures with two liquid phases for understanding the hydrocarbon uptake process by cells. Batch cultivation of Candida lipolytica was carried out in shaking flasks and in a tower fermentor with motionless mixers. Micorscopic observation and cell and hydrocarbon concentration distribution in batch cultivation showed that some cells are attached to the large oil drops ad others are free from them. Interfacial tension between oil and water and Sauter mean drop size decreased as cultivation proceeded. On the basis of the experimental results, the process of hydrocarbon uptake by cells is discussed.
Glucoamylase and glucose oxidase preparations and their combined application for conversion of maltose to gluconic acid
Authors: Cho Y. K. , Bailey J. E. 
Published: December 2004

AbstractThe kinetic behavior of a system of multiple enzyme in solution has been studied in a variable volume batch reactor at pH 5, controlled dissolved oxygen concentration, and T = 30°C. The enzymes used were glucoamylase (R. delemar), glucose oxidase (A. niger), and gluconolactonase (A. niger), all of which are important commercial biocatalysts, and a disaccharide was employed as the starting substrate. This study includes the basic kinetic properties of individual enzymes and interactions between components of the reaction mixture. Classical Michaelis–Menten single substrate or two substrate kinetic with parameters based on initial rate data predict correctly the batch time course of the sequential reaction network.
Pressure drop, gas hold‐up, and oxygen transfer in tower systems
Authors: Hsu K. H. , Erickson L. E. , Fan L. T. 
Published: December 2004

AbstractPressure drop, gas hold‐up, and oxygen transfer were investigated in a sieve tray column, a column with Koch motionless mixers, and a bubble column. The oxygen transfer experiments were conducted using cocurrent flow of gas and liquid under steady‐state conditions with oxygen transfer from the gas to the liquid phase. The oxygen transfer rates and efficiencies of the sieve tray column and the column with Koch mixers were found to be superior to those of the conventional bubble column. Gas hold‐up was also greater when sieve trays or Koch mixers were inserted in the tower. The pressure drop was found to be primarily due to the liquid head in all three columns.
Bacteriolysis by immobilized enzymes
Authors: Karube Isao , Suganuma Toshiro , Suzuki Shuichi 
Published: December 2004

AbstractBacteriolytic enzymes produced by Achromobacter lunatus were immobilized in collagen membrane. Intact bacteria such as Pseudomonas solanacearum, Xanthomonas oryzae, Staphylococcus aureus, and Pseudomonas aeruginosa were lyzed with the bacteriolytic enzyme–collagen membrane. Relative activity of the bacteriolytic enzyme–collagen membrane against Pseu. solanacearum was about 2% of that of native bacteriolytic enzymes. No difference in the optimum pH was observed between immobilized enzymes and native enzymes. The bacteriolytic enzymes in the collagen membrane were stable in the pH range from 4 to 11. The enzyme–collagen membrane was stable against sodium chloride which was an inhibitor of the native bacteriolytic enzymes. Xanthomonas oryzae and Pseu. aeruginosa were continuously lyzed by a reactor containing the rolled bacteriolytic enzyme–collagen membrane.
Pretreatment of cellulosic wastes to increase enzyme reactivity
Authors: Nesse Norvald , Wallick Jack , Harper Judson M. 
Published: December 2004

AbstractThe enzymatic hydrolysis of cellulose to glucose is generally a slow reaction. Different pretreatments, such as ball milling to a −200 mesh or swelling in 1–2% NaOH are reported to increase the reactivity considerably.In this work a fiber fraction from cattle manure was treated in an autoclave for 5–30 min at temperatures ranging from 130–200°C. The reactivity of the cellulose, measured by incubating samples with a commercial cellulase preparation for one hour at 50°C and pH 4.8, was increased by a factor of 4–6 compared to NaOH treatment and 10–12 compared to untreated fiber. The increased reaction rate is probably mostly due to an increase in cellulose availability to enzymatic attack, as structural hemicellulose is hydrolyzed and removed during the treatment.Sugars, produced by hemicellulosis, hydrolysis, will react further to give caramelization products. These side reactions were shown to be suppressed by short treatment times. The treated fiber could support growth of a mixed culture of Trichoderma viride and Candida utilis only after washing, indicating the formation of water soluble inhibitory products during treatment.The treatment with high‐temperature steam can probably be used also with other cellulosic materials to increase reactivity. This may be an attractive way to prepare low‐valued wastes such as manure fibers, straw, stalks, or corn cobs for fermentation processes to increase the protein content or for use directly as ruminant animal feed.
Continuous cultivation of Trichoderma viride on cellulose
Authors: Peitersen Nicolai 
Published: December 2004

AbstractUsing ball milled cellulose as the only carbon source Trichoderma viride was grown in a continuous flow culture at pH = 5.0 and T = 30°C. Steady‐state values for cell protein, cellulose, and cellulase for different substrate concentrations (4–11 g/liter) and dilution rates (0.033–0.080 hr−1) were obtained. Under steady‐state conditions, 50–75% of the cellulose was consumed indicating a critical dilution rate on 0.17 hr−1.Cellulase activity (U/ml) in the fermentation broth increased slightly with increasing substrate concentration and decreased with increasing dilution rate, while the specific cellulase productivity (U/mg cell protein·hr) was fairly independent of the dilution rate, with a maximum around D = 0.05 hr−1.Following step changes in substrate concentration and dilution rate, new steady‐state values were reached after three to five residence times (cell protein and cellulose) and four to six residence times (celullase activity).
Enzymatic treatment of primary municipal sludge with Trichoderma viride cellulase
Authors: Cinq‐Mars Gerald V. , Howell John 
Published: December 2004

AbstractEnzymatic hydrolysis of the cellulose in raw primary settled municipal sludge by Trichoderma viride cellulase achieved conversions of up to 75% of the cellulose, primarily to cellobiose, in 24 hr. Simultaneously the gel‐like characteristic of raw primary sludge was changed to that of a slurry of fine particles in less than 2 hr, causing a radical change in the ability to ultrafilter the sludge.The use of raw primary sludge as a growth medium for T. viride cellulase production was also investigated. It was possible, with nitrogen supplements, to obtain an enzyme with a filter paper activity (FPA) of two compared to over four which is attainable on defined medium of similar strength.The potential use of cellulase treatment as a pretreatment or integral part of waste treatment processes is discussed and the alternatives evaluated.
Aeration without air: Oxygen supply by hydrogen peroxide
Authors: Schlegel H. G. 
Published: December 2004

AbstractOxygen has been supplied to suspensions of microorganisms kept under nitrogen by the addition of hydrogen peroxide. If catalase was present in the suspension and the flow was adjusted to the rate of oxygen consumption, the cells grew at rates identical to the controls incubated under air. The applicability of oxygen supply by hydrogen peroxide and its limits are discussed.
Kinetics of phosphate limited algal growth
Authors: Nyholm Niels 
Published: December 2004

AbstractThe kinetics of phosphate limited growth of two green algae Chorella pyrenoidosa and Selenastrum capricornutum have been studied in chemostats. Several kinetic models which express the specific growth rate as a function of the intracellular phosphours content have been examined, and one of the models was found to be significantly better than the other models. The principles of this model were described in a recent paper by Nyholm.The kinetics of phosphate uptake have been investigated by adding pulses of phosphate to the chemostats. The uptake by phosphours deficient cells could be described by Michaelis–Menten kinetics for phosphate concentrations below approximately 500 μg P/liter. Further, with the assumption of a discontinuous adjustment of the uptake rate at the onset of phosphours deficiency, a complete kinetic model for growth and phosphate removal is proposed.The mean cell size and the contents of chlorophyll and RNA per unit dry weight have been measured for C. pyrenoidosa as a function of the dilution rate.
Oxygen transfer and axial dispersion in an aeration tower containing static mixers
Authors: Maclean G. T. , Erickson L. E. , Hsu K. H. , Fan L. T. 
Published: December 2004

AbstractOxygen transfer from gas to liquid under steady‐state cocurrent flow conditions was modeled using the dispersion model, and the oxygen transfer coefficients were estimated from available data for a column with Koch motionless mixers. The dispersion in the column was estimated for several different gas and liquid flow rates using steady‐state tracer experiments. The estimated oxygen transfer coefficients were compared with those estimated using complete mixing and plug flow models. The results indicate that the dispersion model is the most appropriate model for estimating the mass transfer coefficient from the available data.
Growth characteristics of Candida utilis on volatile substrate in a multistage tower fermentor
Authors: Páca Jan , Grégr Vratislav 
Published: December 2004

AbstractThe influence of increasing ethanol concentration in the feed on growth and physiological activity of the yeast Candida utilis was studied. The measurements were made at steady states of continuous culture under constant values of dilution rate, temperature, and pH in all stages of the fermentor. Synthetic ethanol was used as the sole source of carbon and energy in the concentration range 10–100 g/liter.The maximum biomass concentration in the effluent and maximum productivity was achieved at 75 g ethanol/liter in the feed. In respect to ethanol losses in the outlet and biomass yield, the optimum ethanol concentration in the input of the growth medium was found to be about 50 g/liter using a four‐stage system.
Pepsin immobilized on inorganic supports for the continuous coagulation of skim milk
Authors: Taylor M. J. , Cheryan M. , Richardson T. , Olson N. F. 
Published: December 2004

AbstractThe milk‐clotting enzyme pepsin was immobilized onto beads of alumina, titania, glass, stainless steel, iron oxide, and Teflon for treating skim milk in a fluidized‐bed reactor. Two covalent attachment procedures using silanized supports and glutaraldehyde and two adsorption procedures were evaluated. The three best catalysts were titania and glass, using the covalent attachment procedure, and alumina, using the adsorption procedure at pH 1.2. The pepsin adsorbed on alumina catalyst has commercial potential compared to the previously used glass catalyst. Attempts to increase the stability of pepsin adsorbed on alumina by cross‐linking with glutaraldehyde were unsuccessful owing to the low pH necessary for optimum pepsin adsorption. Desorption of pepsin from alumina during reactor operation was determined. Regeneration of spent catalysts was only partially successful.
Growth kinetics and cellulase biosynthesis in the continuous culture of Trichoderma viride
Authors: Brown D. E. , Zainudeen M. A. 
Published: December 2004

AbstractContinuous culture studies have been carried out growing Trichoderma viride QM 9123 in a 10 liter stirred fermentor on a medium containing commercial glucose as the carbon source. Experiments were carried out at 30°C and at three controlled pH values of 2.5, 3.0, and 4.0, over a range of dilution rates from 0.01 to 0.11 hr−1. Steady‐state values of cell, glucose, and cellulase concentration oxygen tension, and outlet gas oxygen partial pressure were recorded. Values of maximum specific growth rate, endogenous metabolism coefficient, Michaelis‐Menten coefficient, yield and maintenance coefficient for glucose were derived and correlated the effect of the hydrogen ion concentration. Specific oxygen uptake rates were correlated with specific growth rates and absorption coefficients were shown to be a function of dilution rate independent of pH. Some data on cellulase biosynthesis were examined and correlated in terms of a maturation time model.
Photocontrol of immobilized trypsin activity
Authors: Nakmoto Yoshiaki , Nishida Morie , Karube Isao , Suzuki Shuichi 
Published: December 2004

AbstractTrypsin was coupled on an agarose gel which was modified with a spiropyran compound. The trypsin–spiropyran (agarose) gel showed reverse photochromism. The activity of the trypsin–spiropyran gel in the dark was 12% of that of native trypsin, and it was higher than that under visible light. The apparent Michaelis constant of the trypsin–spiropyran gel in the dark was larger than that under visible light. On the other hand, the maximum velocity in the dark was higher than that under visible light. The optimum pH of the trypsin–spiropyran gel in the dark was the same as that under visible light. Immobilized trypsin was stable in the pH range from 3 to 9. The trypsin–spiropyran gel was more stable against heat than the native trypsin.