bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some properties of a protease (subtilisin BPN′) immobilized to porous glass
Authors: Chapman J. Douglas , Hultin Herbert O. 
Published: December 2004

AbstractSubtilisin BPN′ was immobilized to porous glass via isothiocyanate coupling. The pH optimum of the enzyme was shifted to the alkaline side on binding. This effect was more pronounced with ethyl lactate than with N‐tosyl arginine methyl ester (TAME). Presumably, the shift is a reflection of the negative charge on the surface of the glass. The Michaelis constant and Vmax of soluble subtilisin BPN′ with TAME were two and one orders of magnitude, respectively, lower than with ethyl lactate. Vmax, calculated per g of active enzyme, with TAME as the substrate was not affected by immobilization, while Vmax with ethyl lactate decreased greater than tenfold. The apparent KM decreased on immobilization with ethyl lactate as substrate and increased with TAME. Results are explained in terms of diffusional resistance and a possible attraction of ethyl lactate to the glass surface. Active site titration indicated that about 25%, of the immobilized enzyme was active.
Urocanic acid production using whole cells immobilized in a hollow fiber reactor
Authors: Kan J. K. , Shuler M. L. 
Published: December 2004

AbstractThe feasibility of using hollow fiber membrane dialyzers (C‐DAK) for immobilization of microbial whole cells was investigated. The cells are located on the shell side of the dialyzer, while substrates and products are free to diffuse across the hollow fiber membranes. The biochemical reaction studied was the conversion of L‐histidine to urocanic acid and catalyzed by L‐histidine ammonia‐lyase. C‐DAK dialyzers containing a heat‐treated suspension of Pseudomonas fluorescens ATCC 11299b (with L‐histidine ammonia–lyase activity) were incorporated into constant volume recycle reactor systems for continuous product formation. A simple model successfully correlated the data and predicted performance. It was found that the reaction was not likely to be diffusion limited, and such a cell immobilization scheme is convenient and workable for continuous production of biochemicals.
Continuous production of NADP by immobilized Achromobacter aceris cells
Authors: Uchida Tomofumi , Watanabe Taizo , Kato Jyoji , Chibata Ichiro 
Published: December 2004

AbstractSeveral microorganisms having higher nicotinamide adenine dinucleotide kinase (NAD kinase, EC 2.7.1.23) activity were immobilized into polyacrylamide gel lattices. The enzyme activity yield by immobilization was highest in Achromobacter aceris AKU 0120. By the incubation of the immobilized A. aceris cells at pH 4.0, the NAD kinase activity increased and the adenosine triphosphate(ATP)‐degradation activity disappeared completely. Enzymic properties of the immobilized A. aceris cells were investigated and compared with those of intact cells. The optimal pH and the optimal temperature of immobilized cells were the same as those of intact cells. Immobilized cell NAD kinase was more stable than that of intact cells. The operational half‐life of immobilized cells was 20 days when the substrate solution was passed through a column packed with immobilized cells at a flow rate which gives a space velocity (SV) of 0.1 hr−1 at 37°C. On the other hand, the half‐life of the intact cells was only 6 hr.
Preparation and properties of immobilized methanol oxidase
Authors: Baratti J. , Couderc R. , Cooney C. L. , Wang D. I. C. 
Published: December 2004

AbstractMethanol oxidase produced by the yeast Hansenula polymorpha DL‐1 was used for the enzymatic oxidation of methanol to formaldehyde. The kinetics of enzyme and protein release during cell desruption were studied at the laboratory scale with a Braun homogenizer and the pilot plant scale with a Manton–Gaulin homogenizer. Conditions were defined for maximum release and retention of high activity in cell‐free extracts. Methanol oxidase was immobilized by adsorption on DEAE‐cellulose from enzymes in cell‐free extracts or from ammonium sulfate purified purified fractions. The kinetics of formaldehyde formation with both soluble and immobilized enzyme was studied in batch and continuous reactors.
Effect of refiner defibrizing on the fermentability of ryegrass straw
Authors: Han Y. W. , Chen W. P. , Miles T. R. 
Published: December 2004

AbstractThe effects of two grinding methods, hammer milling and defibrizing by disk refining, on the fermentability of ryegrass straw were investigated. Disk refined or defibrized straw produced more sugar than hammer milled straw. Release of sugar was especially pronounced when H2SO4 was added to the straw during the defibrizing process. In vitro rumen digestibility was significantly higher (P < 0.1) for defibrized than for hammer milled straw. With semisolid culture the level of yeast growth was about three times as high on the defibrized as on hammer milled straw. A scanning electron micrograph revealed that defibrizing removed the waxy surface of the straw as well as separating fiber bundles, so that the surface area of the exposed fiber structure was increased.
Coprecipitation of acid cheese whey and tannery waste and recovery of protein
Authors: Townend Robert E. 
Published: December 2004

AbstractCombining acid cottage cheese whey and the lime–sulfide effluent from tannery unhairing processes spontaneously coprecipitates the whey proteins with the large peptides and proteins of the tannery waste. The floculation of the denatured protein material also carries down the hide pigments, excess lime, and the casein fines from the whey. The clear supernatant contains lactose, sulfur in various states of oxidation, free amino acids, peptides, and ammonium salts, but no detectable macromolecular proteins. The recovered solid products, which contain more than 20% of the original nitrogen, appear to have a good balance of essential amino acids although actual composition varies with the composition of the raw wastes. Feed supplements may possibly by obtained by this method from two presently wasted industrial effluents.
Immobilization of Streptomyces flavochromogenes pullulanase on tannic acid and TEAE–cellulose
Authors: Ohba Riichiro , Chaen Hiroto , Hayashi Sachio , Ueda Seinosuke 
Published: December 2004

AbstractPullulanase was immobilized successfully by simple, inexpensive methods that may be useful for industrial application of this enzyme. A tannin–pullulanase(TP) complex was obtained by addition of tannic acid to the culture filtrate of thermophilic Streptomyces flavochromogenes. TP could be bound to TEAE–cellulose (TTCP). Immobilization in this manner took place with quantitative retention of activity. The immobilized enzymes were stable for more than six months. The optimum temperatures of the native enzyme and TP were both 50°C; that of TTCP was 45°C. In the presence of 5mM Ca2+, the activity of TTCP was increased approximately twofold and the optimum temperature was raised to 50–60°C. Pullulanase was not significantly eluted from TP or TTCP by NaCl Solution (0.1–0.5M).
Enhancement of oxygen absorption into sodium sulfite solutions
Authors: Linek V. , Beneš P. 
Published: December 2004

AbstractOxygen absorption enhancement in a sodium sulfite solution was studied in the absence and presence of copper catalyst both for absorption across the liquid surface in a stirred cell and for absorption from individual bubbles rising through a turbulent liquid. The enhancement factor was determined from the ratio of oxygen and argon mass transfer coefficients, measured under identical experimental conditions in the same batch of liquid. It has been found that the oxygen absorption is not chemically enhanced, as long as the mass transfer coefficient, kL0, is high enough, i.e., higher than the value 1.4 × 10−4 m sec−1 for the sulfite solution we used. An analysis of our data as well as literature data indicates that the sulfite system is poorly suited for studies of the volumetric mass transfer coefficient of physical absorption (kL0a) in fermentors, inasmuch as oxygen absorption can be chemically enhanced while the degree of enhancement depends on the operating conditions of batch aeration, as well as on the concentration of trace impurities with catalytic effects upon the sulfite solution used.
The rotorfermentor. II. Application to ethanol fermentation
Authors: Margaritis Argyrios , Wilke Charles R. 
Published: December 2004

AbstractThe kinetics of microbial growth and product formation are described as applied to the high cell concentration scheme of the rotorfermentor. A bench scale pilot plant was designed and built in order to demonstrate the operational feasibility of the rotorfermentor. The fermentation of glucose to ethanol by Saccharomyces cerevisiae ATCC 4126 was used. When the rotorfermentor was used with a glucose feed concentration of 104 g/liter almost 100% glucose utilization was obtained and the ethanol productivity rate was 27.3 g ethanol/liter hr which was found to be about 10 times greater than the ethanol productivity obtained from an ordinary continuous stirred tank (CST) Fermentor. The ethanol experimental results obtained from the rotorfermentor and an ordinary CST fermentor were used as a basis to assess the economic feasibility of the rotorfermentor. The economics of an industrial scale ordinary CST fermentor with and without cell recycle is compared with a rotorfermentor unit for the same ethanol production throughput. For the process conditions considered on this case, calculations showed that the rotorfermentor may replace both a CST fermentor and cell centrifuge resulting in lower capital equipment costs and lower power consumption requirements.
Enzyme deactivation during cellulose hydrolysis
Authors: Howell J. A. , Mangat M. 
Published: December 2004

AbstractHydrolysis of cellulose by Trichoderma viride cellulase reached a plateau after some 25 hr. If the initial enzyme‐to‐substrate ratio was low, resuspension of substrate in fresh enzyme or addition of enzyme resulted in further high rate hydrolysis. This did not occur if the initial ratio was high. Over 75% hydrolysis might be achieved in the former case, while less than 60% in the latter. A model postulating inactivation of adsorbed enzyme–substrate complex which blocked further hydrolysis was proposed, and it was found to fit the data well. The proposed model had five parameters, four of which could be checked by graphical methods, and all of which had physical meanings. The parameters were estimated by a nonlinear least‐squares minimization FORTRAN computer program, using numerical integration and optimization of the parameters. The model was used to predict the resuspension data, powdered enzyme addition data, cellobiose addition data, and cellulose addition data; the deviations from the model are discussed. It was found that average values could be used for four out of the five parameters, while the fifth (initial enzyme concentration) did not correlate with independent measurements such as the filter paper activity or protein concentration.
Continuous fractionation of human plasma
Authors: Mitra Gautam , Lundblad John 
Published: December 2004

AbstractContinuous processing has been applied to human plasma fractionation by the cold ethanol process. On‐line pH control of ±0.05 pH units, flow control of ±1%, and temperature control of ±0.5°C have been achieved. Optimization of precipitation pHs has been carried out for purifying plasma protein fractions and albumin. During precipitation, the irreversible nature of the pH overshoots has been demonstrated. Compared to the batch processing mode, the continuous scheme produces an increased yield between 6 to 11%.
Effect of inoculum size on the aeration pattern of batch cultures of a fungal microorganism
Authors: Brown D. E. , Zainudeen M. A. 
Published: December 2004

AbstractTrichoderma reesei QM 9123 has been grown in batch culture in a 10 liter stirred fermentor, at a temperature of 30°C and pH 4.0. The fermentor was operated at a single stirrer speed of 400 rpm and air rate of 1 v/v/m. The effect of four inoculum sizes (0.5, 1.0, 3.0 and 5.0%) on the growth pattern and the aeration profiles was examined. Logarithmic growth of the fungus was observed. The aeration profile changed with inoculum size and at 5.0%, it was found that the oxygen uptake rate was controlled by the oxygen supply rate, during which the oxygen tension was zero.
Treatment of primary sewage sludge with enzymes
Authors: Knapp Jeremy S. , Howell John A. 
Published: December 2004

AbstractThe effect of cellulase treatment on the physical dewatering of primary sewage sludge has been investigated. Although cellulase treatment rapidly increases the sedimentation rate of diluted sludge, no significant advantage has been found in the settling of undiluted sludge. An extract produced from cellulase‐treated sewage sludge has been used as a medium for the growth of yeast with a view to single‐cell protein production.
Immobilization of glucose isomerase to ion‐exchange materials
Authors: Huitron C. , Limon‐Lason J. 
Published: December 2004

AbstractGlucose isomerase (D‐xylose ketol‐isomerase EC 5.3.1.5) from Bacillus Coagulans was partially purified and immobilized by adsorption to anion exchangers. The highest activities were obtained when the enzyme was adsorbed to DEAE‐cellulose. On immobilization to DEAE‐cellulose the measured optimum pH value for enzyme activity shifted from 7.2 to 6.8. There was no appreciable difference between the heat stabilities of soluble and immobilized enzyme. The Km app values for the immobilized enzyme were found to be 0.25M in the presence of 0.01M Mg2+ and 0.19M with 0.005M Mg2+, while those enzyme were 0.11 and 0.17M, re spectively. Under conditions of contimuous of D‐glucose, a decrease of activity with time was observed, but this decrease was less at a low Mg2+ concentration and was affected by column geometry. There were no appreciable diffusional limitation effects in packed‐bed columns.
Design and oxygen‐transfer potential of a pulsed continuous tubular fermentor
Authors: Serieys M. , Goma G. , Durand G. 
Published: December 2004

AbstractA new type of continuous fermentor has been developed which features an agitation‐aeration system based on pulsed flow across perforated plates the use of plug flow to achieve a concentration gradient. The influence of the agitation‐aeration parameters (in this case the pulsed speed) has been measured, and mathematical models have been produced for the gas hold‐up, the power dissipated in agitation and aeration, the oxygen‐transfer rate, and efficiency. The oxygen transfer is high, up to 600 mmol/liter hr with a transfer efficiency much higher than that published for any other technique.
Yeast SCP from ethanol: Measurements, modeling, and parameter estimatin in a batch system
Authors: Prokop A. , Votruba J. , Sobotka M. , Panoš J. 
Published: December 2004

AbstractThe production of single‐cell protein (SCP) from ethanol by different imcroorganisms is briefly reviewed. The trends in modeling the SCP production are outlined with a stress on the need to incorporate metabolic and engineering considerations into the pertinent models. Data on batch yeast growth on ethanol are analyzed, a metabolic model involving design parameters is suggested, parameters values are estimated, and their significance is discussed. The model essentially describes the response of a system to disturbances (substrate, metabolites, oxygen, etc.). An effective numerical integration procedure is necessary in the solution of the model which has “stiff” character.
Mathematical models for hollow‐fiber enzyme reactors
Authors: Webster I. A. , Shuler M. L. 
Published: December 2004

AbstractTwo analytically solved mathematical models are presented for a reactor ystem employing immobilized whole cells as a biocatalyst. The whole cells are entrapped or pumped through the shell side of the dialyzer reactor unit. The reactant mixture is circulated through the cialyzer tube side. Nutrient diffuses across the hollow fiber membrane from the tube side to the shell side, where it reacts to form product, which then back diffuses into the reactant mixture stream. The use of a high recirculation ratio of nutrient through the dialyzer tubes to nutrient feed rate to the entire system, allows the system to be modeled as a continuous‐flow stirred‐tank reactor. The first analysis details the development of an effectiveness‐factor correlation for first‐ and zero‐order kinetics. The second analysis presents the solution to an unsteady‐state‐system mass balance with Michaelis–menten kinetics.
Model for oxygen transfer in a shake flask
Authors: Van Suijdam J. C. , Kossen N. W. F. , Joha A. C. 
Published: December 2004

AbstractThe shake flask is a very common and useful tool for the study of submerged fermentations on a small scale. However, the oxygen supply may easily become a limiting factor. A model for the aeration in shake flasks is presented that enables one to predict whether in the course of an experiment the oxygen supply is becoming a growth‐limiting factor or not. The results of measurements of the transfer coefficient of a cotton plug and the oxygen mass‐transfer coefficient kla are also given.
Hydrocarbon fermentation: Kinetics of microbial cell growth
Authors: Goma Gérard , Ribot Denis 
Published: December 2004

AbstractModeling of microbial growth using nonmiscible substrate is studied when kinetics of substrate dissolution is rate limiting. When the substrate concentration is low, the growth rate is described by an analytical relation that can be identified as a Contois relationship. If the substrate concentration is greater than a critical value Scrit, the potentially useful hydrocarbon S* concentration is described by S* = Scrit/(1 + Scrit/S). A relationship was found between Scrit and the biomass concentration X. When X increased, Scrit decreased. The cell growth rate is related to a relation μ = μm[A(X/Scrit)(1 + Scrit/S) + 1]−1. This model describes the evolution of the growth rate when exponential or linear growth occurs, which is related to physico‐chemical properties and hydrodynamic fermentation conditions. Experimental data to support the model are presented.
Continuous culture of Candida lipolytica on n‐hexadecane
Authors: Gutierrez J. R. , Erickson L. E. 
Published: December 2004

AbstractCandida lipolytica was grown continuously on n‐hexadecane as the main source of carbon. A transient continuous‐culture experiment was also conducted to investigate hydrocarbon‐limited growth; the hydrocarbon feed flow rate was stopped for several hours and then resumed at a reduced steady‐state flow rate. Interfacial tension, Sauter mean diameter, pseudosolubility, fraction of cells in the aqueous phase, oil‐phase volume fraction, and cell concentration were measured to characterize the system. The microorganisms appear to utilize both the submicron drops and the microscopic drops. The effects of interfacial tension, pseudosolubility, and unoccupied interfacial area on the kinetics of hydrocarbon fermentation are discussed here. A conceptual model for hydrocarbon uptake is presented and discussed.
Influence of manufacturing variables on the characteristics and effectiveness of chitosan products. I. Chemical composition, viscosity, and molecular‐weight distribution of chitosan products
Authors: Bough W. A. , Salter W. L. , Wu A. C. M. , Perkins B. E. 
Published: December 2004

AbstractTen chitosan products were manufactured from dry shrimp hulls under differing process conditions and compared to a commercially available product. Manufacturing variables tested were: alkali versus enzymatic deproteination; acid demineralization versus no treatment; air versus nitrogen atmosphere; 5 min vs. 15 min deacetylation period: and varying the particle size of the dry starting material. Deproteination by alkali of enzymatic extraction did not substantially affect the nitrogen and ash compositions of dry chitosan samples. However, the viscosity was reduced in samples deproteinated by enzymatic hydrolysis. Elimination of the demineralization step resulted in products having 31–36% ash, as expected. Some differences in viscosity were observed between deminiralized and undemineralized samples, but on important differences in the molecular‐weight distribution of these samples were evident. Purging the reaction vessel with nitrogen resulted in chitosan preparations having higher viscosities and molecular‐weight distributions than those prepared in an air atmosphere. The degradative effect of air became more proshrimp hulls to 1 mm prior to any treatment resulted in a chitosan product of both higher viscosity and molecular weight than when ground to either 2 or 6.4 mm. Viscosity was not always a direct indicator of molecular weight, for although the presence of colloidal particles increased the viscosity of some samples, the molecular‐weight distribution after filtration was essentially the same as in other less viscous samples.
Applied microalgae photosynthesis: Discharge mechanisms in highly illuminated cells
Authors: Contreras S. , Soto M. A. , C. J. Toha 
Published: December 2004

AbstractBased on the hypothesis that discharge mechanisms are induced in highly illuminated thylakoid, we analyze an applied model, which overcomes the damage induced by outdoor solar radiation, partially shaded, air‐bubbled, or stirred blue‐green algae cultures. The blue‐green alga, Oscillatoria sp., exhibits a maximum growth rate at a radiation intensity of 50 J/m2sec. The introduction of 0.1 sec dark periods shifts this peak up to 75 J/m2sec. The radiationless nature of the discharge mechanisms is discussed in accord with the low growth rates of both the experimental and control cultures at 40°C.
The viscostat: Productstat method of feed‐rate control in continuous fermentations
Authors: Silman R. W. , Bagley E. B. 
Published: December 2004

AbstractXanthan biopolymer has been produced in a single‐stage continuous fermentation with Xanthomonas campestirs NRRL B‐1459, using a viscostal control method instead of the conventional chemostat method. A Bendix UltraviscosonThe mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.
sensed the fermentor viscosity, and the recorder–controller actuated the feed medium pump in an on–off control mode. Since all continuous fermentations eventually become contaminated or suffer culture variation, this work served also to demonstrate the effectiveness of the viscostat control. Neither the presence of a mold contaminant with specific growth rates lower than that of X. campestris, nor the presence of a bacterial contaminant of specific growth rate greater than X. campestris, affected the maintenance of constant viscosity in this control system.
Effect of initial substrate concentration on the rate of nitrification in a batch experiment
Authors: Shieh Wen K. , La Motta Enrique J. 
Published: December 2004

AbstractThe intrinsic rate of nitrification was observed in a batch reactor by eliminating external and internal diffusional resistances. The former were minimized by means of intense agitation, and the latter by mechanical rupture of the activated sludge flocs using high mixer rotational speeds. The optimum temperature and pH for the intrinsic nitrification rate were found to be 30–35°C and 8.0, respectively. Initial ammonium concentration was found to have a strong effect on the value of the kinetic parameters of the Michaelis–Menten rate expression at low ammonium levels. However, at high initial concentrations both parameters attained a constant maximum value that is independent of the initial substrate level.