bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of ultraporous fired bricks as support for yeast cell immobilization
Authors: Opara C. C. , Mann J. 
Published: December 2004

AbstractUltraporous fired bricks (porosities from 56 to 72%) were developed from materials locally available in Nigeria. The grog particle size was used to modulate the porosity of the bricks. The porous bricks produced were then employed as supports for the immobilization of a yeast strain isolated from a local alcoholic beverage, palm wine. The influence of a brick's porosity and particle size on the cell‐loading capacity and cell growth inside the fired brick support were studied. The study revealed that a brick's porosity varied linearly with the mean particle size of the grog, increasing from a porosity of 56% at a particle size of 0.805 mm to 72% at a particle size of 0.075 mm. Cell saturation of the surface area available within the support matrix was completed within four hours of contact between the cell and the adsorbing surface especially for the most porous samples. Cell growth was therefore not observed in such cases; however, the less porous samples supported some cell growth upon incubation. Cell holdup was also observed to increase exponentially when either the porosity was increased or the particle size was decreased. The influence of particle size, however, became insignificant at very high porosities.
A new pilot reactor for solid‐state fermentation: Application to the protein enrichment of sugar beet pulp
Authors: Durand A. , Chereau D. 
Published: December 2004

AbstractA new pilot reactor for solid‐state fermentation has been used for single‐cell protein production on raw sugar beet pulp with a mutant, Trichoderma viride T.S. This pilot plant, having a maximum working capacity of one ton (ca. 200 kg dry matter) can be scaled up to the production plant level. During the process, the protein content increases from 9 to 20–21% (on the basis of dry matter) in 48 h. A material and heat balance is presented in relation with temperature and moisture level regulation during the process.
Photo‐osmosis through liquid membrane bilayers generated by bacteriorhodopsin
Authors: Srivastava R. C. , Tandon A. 
Published: December 2004

AbstractLiquid membrane bilayers, generated by bacteriorhodopsin on a supporting membrane, exhibit photo osmosis. The phenomenon has been shown to be a consequence of light‐induced electrical potential differences which develop across the liquid membrane bilayer due to the light‐driven proton pumping action of bacteriorhodopsin. The variations of photo osmotic velocity with wavelength, intensity of light, and proton acceptor concentrations has been studied.
The effect of wood‐derived inhibitors on 2, 3‐butanediol production by Klebsiella pneumoniae
Authors: Nishikawa Nora K. , Sutcliffe Roger , Saddler John N. 
Published: December 2004

AbstractFour potential inhibitors, hydroxymethylfurfural, furfural, syringaldehyde and vanillin, were assayed over a range of concentrations and times to simulate the amounts that might be expected to accumulate when the hydrolyzed water‐soluble fraction from steam‐treated aspenwood was added in a fed‐batch mode to K. pneumoniae. Combinations of the individual materials resulted in a cumulative inhibitory effect. Prolonged incubation could alleviate some of the inhibition.
Problematics and stability of on‐line pH measurements in anaerobic environments: The jellied combined electrode
Authors: Monzambe Kuma M. , Naveau Henry P. , Nyns Edmond‐Jacques , Bogaert Nicolas , Bühler Hans 
Published: December 2004

AbstractDiscrepancies of one pH unit and more have been observed after a few days, between continuous on‐line in situ pH measurements and instant off‐line pH measurements during anaerobic digestion of an agroindustrial wastewater. Concomitantly, the electrical resistance across the porous diaphragm of the on‐line electrode increased, and a black clogging developed on its diaphragm. Measurements of the relative liquid junction potential in KCl or Na2S solutions excluded that high concentrations of ions such as, K+, Na+, Cl−, HS−, or S2− were the major cause of the drifts in pH values. It has been possible to limit the rapid increase of the liquid junction potential and the black clogging formation on the porous diaphragm either by acidification and/or by overpressurization of the electrode‐filling liquid. Continuous on‐line in situ pH values consistent with instant off‐line pH values over long periods of time have been obtained with a newly designed pH sensor in which a special jellied electrode filling replaced the porous diaphragm.
Reversible immobilization of soybean β‐amylase on phenylboronate–agarose
Authors: Viera Francisco Batista , Barragan Beatriz Brena , Busto Beatriz Luna 
Published: December 2004

AbstractSoybean β‐amylase (EC 3.2.1.2) wap immobilized on phenylboronate‐agarose by strong interactive binding. The insoluble derivative was active and more stable to temperature changes than the free enzyme. The absence of enzyme leakage even in the presence of substrate was demonstrated. Changes in pH over a wide range (4.0–8.0) did not affect the stability of the complex. The support could be recovered by sorbitol elution, which demonstrated the reversibility of the binding. Since the enzyme was not retained on phenylagarose under similar conditions, we rejected hydrophobic interactions as a cause of the strong binding of the enzyme to phenylboronate‐agarose. We suggest that the bonding of the enzyme to the phenylboronate ligand occurs by a charge transfer mechanism between the trigonal boronate and the side chain nitrogenated groups. It was concluded that phenylboronate‐agarose has good properties as a support, which recommends its use for the preparation of immobilized enzymes.
Influence of growth substrate on production of cellulase enzymes by Trichoderma harzianum E58
Authors: Mes‐Hartree M. , Hogan C. M. , Saddler J. N. 
Published: December 2004

AbstractCellulase production by Trichoderma harzianum E58 grown on lactose and various cellulosic substrates such as Solka Floe, Avicel, and steamed aspenwood was investigated. The culture filtrates of T. harzianum E58 obtained after growth on these substrates were assayed for their cellulase activities and overall hydrolytic activities. The severity of the steaming conditions used for the aspenwood had a pronounced effect on the cellulolytic activity of the produced culture filtrates. Those substrates that were more readily hydrolyzed by the cellulase complex were the poorest substrates for inducing an active cellulase complex. Substrates such as acid‐impregnated aspenwood and lactose induced a less hydrolytic efficient cellulase complex than more recalcitrant substrates such as microcrystalline cellulose.
Determination of intrinsic parameters for immobilization reactions of catalase and amyloglucosidase in porous glass supports
Authors: Hossain Md. M. , Do D. D. 
Published: December 2004

AbstractExperiments have been carried out for immobilizing enzyme‐catalase and amyloglucosidase in controlled‐pore glass particles of two different pore sizes. The experimental results have been analyzed, initial‐stage analysis for the rate parameters of immobilization reactions and long‐time analysis for determining the evolution of the immobilization process. These investigations suggest that the overall process of immobilization is controlled by the restricted diffusion of enzymes into the pores of the support. As a result, immobilized enzyme (IME) can penetrate only up to a certain distance into the support. The penetration depth of IME for the support–enzyme system mentioned have been evaluated from the experimental bulk enzyme concentration data in a batch recirculation reactor.
Glucoamylase immobilized on acid‐hydrolyzed starch graft polyacrylonitrile
Authors: Slininger P. J. , Fanta G. F. , Abbott T. P. 
Published: December 2004

AbstractA continuous stirred reactor fed maltose as substrate was used to show that acid hydrolyzed starch‐g‐polyacry‐lonitrile and other polysaccharide graft copolymers can bind and retain significant quantities of active glucoamy‐lase. Glucose productivities up to 2.7 g/g carrier/h were observed with the immobilized glucoamylase, and half‐lives up to 1800 h were indicative of activity longevity. Factors influencing the immobilized enzyme activity and first‐order decay rate included temperature, pH, and carrier composition. In all cases, maltose was converted quantitatively to glucose with no evidence of reversion product formation.
Performance of recombinant fermentation and evaluation of gene expression efficiency for gene product in two‐stage continuous culture system
Authors: Lee Sun Bok , Ryu Dewey D. Y. , Seigel Robert , Park Sung Hoon 
Published: December 2004

AbstractIn order to develop a general methodology for evaluation of the gene expression efficiency for gene product, theoretical and experimental studies were undertaken using a recombinant Escherichia coli K12ΔH1Δtrp/ pPLc23trpA1 as a “gene–host cell” model system in a two‐stage continuous‐culture system. For this, a genetically structured kinetic model proposed earlier for biosynthesis of gene product in batch cultivation was extended to the two‐stage continuous‐culture system. A partial list of key parameters of the model includes the rate of plasmid segregation, specific growth rate of recombinant cell, plasmid content, rates of transcription and translation, and other parameters related to product biosynthesis. The dynamics of heterogeneous cell population containing plasmid‐harboring and plasmid‐free cells were also studied. Theoretical analysis of cell population dynamics shows that the recombinant cells could be maintained stably for a prolonged time in a two‐stage continuous‐culture system. Fermentation performance of the recombinant E. Coli cells in a two‐stage continuous bioreactor system was examined experimentally, and the gene expression efficiency of a cloned gene product was determined based on the genetically structured kinetic model proposed. Based on our experimental results, the gene expression efficiency of the model gene–host cell system was found to be about twofold more efficient (i. e., 41.8 mg TrpA protein/mg plasmid DNA) as compared to the average rate of protein biosynthesis by E. coli cells. The performance of two‐stage recombinant fermentation was also simulated using a mathematical model developed. General trends obtained from the model simulation agree reasonably well with the currently available experimental data, although further refinements need to be made. The methodology illustrated in this article could be used for evaluation of the gene expression efficiency of other genetically engineered recombinants once such recombinants with certain gene–host cell systems are constructed.
Adaptive optimization of a continuous culture with the use of a bilevel forgetting factor
Authors: Chang Y. K. , Pyun Y. R. , Lim H. C. 
Published: December 2004

AbstractAn adaptive optimization algorithm using a dynamic identification scheme with a bilevel forgetting factor (BFF) has been developed. The simulation results show superiority of this method to other methods when applied to maximize the cellular productivity of a continuous culture of baker's yeast, Saccharomyces cerievisiae. Within the limited ranges of tuning parameters tested the BFF algorithm is found to be superior in terms of initial optimization speed and accuracy and reoptimization speed and accuracy when there is an external change and long term stability (removal of “blowing up” phenomena). Algorithms tested include those based on a constant forgetting factor, an adaptive variable forgetting factor (VFF) and moving window (MW) identification.
Anaerobic acidogenesis of a complex wastewater: I. The influence of operational parameters on reactor performance
Authors: Dinopoulou Georgia , Rudd Thomasine , Lester John N. 
Published: December 2004

AbstractThe influence of operational, parameters, such as hydraulic retention time, organic loading rate, influent substrate concentration, pH, and temperature, on the performance of the first phase of anaerobic digestion has been investigated. A complex substrate based on beef extract was used, and six series of experimental runs were conducted, each one showing the effect of one operational variable. The predominant fermentation products were always acetic and propionic acid, independent of the values of the operational parameters. For initial COD concentrations and hydraulic retention times above the critical values identified as 3 g/L and 6 h, respectively, the degree of acidification achieved was between 30 and 60%. The degree of acidification was found to increase with the hydraulic retention time and decrease with the influent substrate concentration and organic loading rate, while the opposite held true for the rate of product formation. Furthermore, it has been demonstrated that acidification is primarily determined by the hydraulic retention time and the rate of product formation by the influent substrate concentration. The concentration of the acetic acid produced was found to depend on the operational parameters. However, the concentration of propionic acid produced depended only on the substrate availability with a consistent proportion of 8% initial COD converted to it. The optimum pH and temperature were 7 and 40°C, respectively. The percentage of acetic acid as a proportion of the total volatile fatty acids produced was found to increase with increasing pH and temperature, while the percentage of propionic acid seemed to decrease accordingly. Finally the effect of the temperature on the rate of acidification followed an Arrhenius type equation with an activation energy equal to 4739 cal/mol.
The barley protein degradation: Mechanism of protein solubilization during barley mashing with neutral proteinase
Authors: Marković Ivan , Topolovec Velimir , Marić Vladimir , Johanides Vera 
Published: December 2004

AbstractKinetics of protein solubilization during barley mashing with neutral proteinase were studied. By plotting the kinetics data in Foster–Niemann coordinates for barley concentration range of 10–30% linear relationships with high correlation coefficients (r ⩾ 0. 999) were obtained. The slopes of straight lines were very close to corresponding reciprocal initial insoluble nitrogen concentrations. Barley proteolytic inhibitors affected the ordinate intercept; by their addition the values of ordinate intercept decreased. The data suggest that the modified Foster–Niemann equation can be proposed to interpret kinetics of insoluble barley protein degradation. The proteolytic activity decay was studied as well. The enzyme decay was faster in buffer solution than during barley mashing, but in both cases first‐order kinetics can be applied. A mathematical model describing protein solubilization and enzyme decay kinetics were developed. The results of computer simulation were in good agreement with experimental data.
Continuous regeneration of ATP in enzyme membrane reactor for enzymatic syntheses
Authors: Berke Wolfgang , Schüz Hans‐Jürgen , Wandrey Christian , Morr Michael , Denda Gudrun , Kula Maria‐Regina 
Published: December 2004

AbstractThis work shows that the enzyme membrane reactor offers the opportunity to carry out the enzymatic regeneration of ATP providing continuous operation with high performance. In this system, the coenzyme is immobilized on a water‐soluble polymer. These high‐molecular weight derivates are entrapped within an ultrafiltration membrane together with the enzymes for production of regeneration. Several polymer derivatives of ATP have been prepared for this immobilization technique. Coenzymatic activity of these derivatives was studied with several enzymes for both ATP‐requiring and ATP‐regenerating reactions. PEG‐N6‐aminohexyl‐ATP was selected as the appropriate coenzyme for operating the enzyme membrane reactor. Acetate kinase was the only enzyme providing enough activity for regeneration. Production of glucose‐6‐phosphate is cited as the first example. The kinetics of acetate kinase and hexokinase were examined and used to choose the operating conditions of the process. The process operated continuously for more than 1 month. With a mean conversion of 80%, the space–time yield amounted to 348 g glucose‐6‐phosphate/L d. The cycle number of ATP was estimated as 20, 000 mol/mol. With the continuous production of γ‐glutamylcysteine and NADP, the feasibility of the system was proven.
Controlled fed‐batch fermentation of recombinant Saccharomyces cerevisiae to produce hepatitis B surface antigen
Authors: Hsieh Jih‐Han , Shih Kun‐Yu , Kung Hsiang‐Fu , Shiang Ming , Lee Lan‐Ying , Meng Meng‐Hsiao , Chang Ching‐Chuan , Lin Hui‐Min , Shih Shu‐Ching , Lee Shu‐Ying , Chow Teh‐Yuan , Feng Teng‐Yung , Kuo Tsong‐Teh , Choo Kong‐Bung 
Published: December 2004

AbstractWe have performed controlled fed‐batch fermentation experiments to compare the production level of hepatitis B surface antigen (HBsAg) by recombinant yeast Saccharomyces cerevisiae strains (YNN27/pYBH‐1, YNN27/ p2μ‐S11, YNN27/pDCB‐S2) containing plasmid vector with alcohol dehydrogenase (ADH1), acid phosphatase (PHO5), and glyceraldehyde‐3‐phosphate dehydrogenase (GPD) promoter, respectively. Yeast cell concentrations of 15‐35 g dry cell weight/L were obtained. By limiting phosphorous concentration, HBsAg expression level for the YNN27/p2μ‐S11 strain with inducible PHO5 promoter reached 0.2–0.3 mg/L. By controlling nutrient addition rate and dissolved oxygen concentration, HBsAg concentrations of 3‐10 mg/L were achieved in 60–70 h fermentation using the YNN27/pDCB‐S2 strain with the constitutive GPD promoter.
Fermentation of single and mixed substrates by the parent and an acid‐tolerant, mutant strain of Clostridium Thermoaceticum
Authors: Brumm Phillip J. 
Published: December 2004

AbstractGrowth of the parent and acid‐tolerant mutant strains of Clostridiurn thermoaceticum was examined on a variety of substrates and mixtures of substrates. Nondiauxic growth was noted for both strains on combinations of carbohydrates, organic acids, or a carbohydrate and an organic acid. The mutant strain was able to grow on DL‐lactate as sole energy source. The parent strain would not grow on lactate as sole energy source but consumed lactate when presented with a second fermentable substrate. Neither strain would grow on formate as sole energy source, but both consumed formate when presented with a second fermentable substrate.
Mathematical modeling of affinity ultrafiltration process
Authors: Luong J. H. T. , Male K. B. , Nguyen A. L. , Mulchandani A. 
Published: December 2004

AbstractAn affinity ultrafiltration process has been developed by exploiting affinity binding in conjunction with cross‐flow filtration. The process was proven to possess high resolution, high recovery yield, and ease of scale‐up. The process could purify trypsin from a trypsin‐chymotrypsin mixture batchwise or continuously. Essential for applying this concept was the synthesis of a water‐soluble high‐molecular‐weight polymer bearing m‐aminobenzamidine, a strong and specific trypsin in hibitor. A mathematical model was also developed to describe the dynamic behavior of the newly developed purification process. The model was able to predict the profiles of enzyme concentrations in the process with high accuracy.
Correlation for volumetric mass transfer coefficient in mechanically agitated aerated vessel for oxygen absorption in aqueous electrolyte solutions
Authors: Linek V. , Beneš P. , Holeček O. 
Published: December 2004

AbstractEmpirical equations used so for for computing kla in mechanically agitated aerated vessels agree well with the measured dependence of Kla on the power input of the stirrer and the superficial velocity of the gas. However, they do not fit the dependence of Kla on the physical properties of the liquid batch. From the data published so far it can be deduced that the equations suitable for the description of the dependence of kmola on the liquid physical properties must include some independent variable, which characterizes the rate of coalescence of the bubbles. About 400 experimental values of Kla were compared with those calculated from different relations. This comparison shows that the rate of coalescence for the aqueous electrolyte solutions is well described on the basis of the Gibbs theory of adsorption of the solute in the surface layer of the solution.
The hydrolysis of triglycerides by immobilized lipase in a hydrophiiic membrane reactor
Authors: Pronk W. , Kerkhof P. J. A. M. , Van Helden C. , Riet K. van'T 
Published: December 2004

AbstractIn the present article a method is described to immobilize lipase from Candida rugosa on a hollow fiber membrane, and the use of such a system for the hydrolysis of lipids is reported. The membranes were ENKA hydro philic Cuprophan®‐type hollow fibers, having a large specific surface area. The immobilized lipase exhibited a high stability: the half‐life time was 43 days at a temperature of 30°C. Furthermore, it is proved that kinetic studies can be carried out with this system, operated in a batch or continuous mode. The relation between conversion rate and degree of hydrolysis was determined. On this basis, a dynamic model of the process was developed that describes the relation between reaction conditions and the conversion rate.
Biochemical switching device: Monocyclic enzyme system
Authors: Okamoto Masahiro , Sakai Toshio , Hayashi Katsuya 
Published: December 2004

AbstractThe switching characteristics of a monocyclic enzyme system, in which two enzymes share substrates or co‐factors in a cyclic manner, such as, → X1 + B + E1 ⇄ A + E1 + X2 →, → X3 + A + E2 ⇄ B + E2 + X4 → (E1, E2 are enzymes, X1, X3 are substrates, X2, X4 are products, A, B are cofactors), were demonstrated using computer simulations. The detailed mathematical models of biochemically possible cyclic enzyme systems were built up and the effects of rate constants and the effects of initial concentrations of enzymes and cofactors on switching characteristics were discussed. The cyclic enzyme system could function as a switching circuit when the initial concentrations of enzymes or cofactors are over a certain threshold value. Based on the present results, we further discuss the dynamic characteristics of a biochemical reactor system (bioreactor) involving this cyclic enzyme system as a switching controller.