bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic production of cyclodextrins from milled corn starch in an ultrafiltration membrane bioreactor
Authors: Kim Tae‐Jong , Lee Yun‐Dong , Kim Hak‐Sung 
Published: December 2004

AbstractCyclodextrin glycosyltransferase (CGTase) was found to be severely inhibited by cyclodextrins. In order to increase the conversion yield by reducing product inhibition and reuse the CGTase in the production of cyclodextrins from milled corn starch, an ultrafiltration membrane bioreactor system was employed. In a batch operation with ultrafiltration, the conversion yield was increased 57% compared with that without ultrafiltration. Operating conditions for the continuous production of cyclodextrins in the membrane bioreactor were optimized by taking into consideration the filtration rate and the conversion yield as follows: initial starch concentration, 7% (w/v); starch feeding rate, 240 mg/h; CGTase loading, 350 units/initial gram starch. When cyclodextrins were continuously produced in the membrane bioreactor under optimized conditions, 340 units of CGTase was require to produce 1 g of cyclodextrins for 48 h, while in the case of conventional batch operation, 1 g of cyclodextrins was produced for 24 h by 1410 units of CGTase. © 1993 John Wiley & Sons, Inc.
The effect of organic solvents on the equilibrium position of enzymatic acylglycerol synthesis
Authors: Janseen Anja E. M. , Van der Padt Albert , Van Sonsbeek Henk M. , Van't Riet Klaas 
Published: December 2004

AbstractThe effect of organic solvents on the equilibrium position of lipase‐catalyzed esterification of glycerol and decanoic acid has been investigated. The reaction is carried out in an aqueous‐organic two‐phase system. In polar solvents, high mole fractions of monoacylglycerol and low mole fractions of triacylglycerol and measured, while in nonpolar solvents, the measured differences in the mole fractions of monodi‐, and triacylglycerols are less. There is a good correlation between the ester mole fractions at equilibrium and the log P of the solvent (partition coefficient in n‐octanolwater), however, only if the group of tertiary alcohols is excluded. In the plot of the easter mole fractions as a function of the logarithm of hte solubility of water in the organic solvent, the tertiary alcohols can be included; however, in this case other deviations appear.For the prediction of the effect of organic solvents on the ester mole fractions at reaction equilibrium in nondilute reaction systems with a water activity below 1, the program TREP (Two‐phase Reaction Equilibrium Prediction) is developed, which is based on the UNIFAC group contribution method. With this model the equilibrium data are essentially predicted from basic thermodynamic data. The required equilibrium constants are estimated from experiments without an organic solvent in the reaction medium. The mole fractions calculated by TREP show the same trends as the experimentally measured mole fractions; however, some variation is observed in the absolute values. These deviations may be due to inaccuracies in the UNIFAC group contribution method. TREP is found to be a correct method to predict within some limits the ester mole fractions at equilibrium for all mixtures of solvents, substrates, and products. The production of monoester can be enhanced in reaction system with a sufficient high concentration of a polar solvent. In experiments with a triglymeto‐decanoic acid ratio of 5, almost no di‐and triesters can be detected at equilibrium. © 1993 John Wiley & Sons, Inc.
Kinetic characterization of baculovirus‐induced cell death in insect cell cultures
Authors: Wu Suh‐Chin , Dale Bruce E. , Liao James C. 
Published: December 2004

AbstractThe death process of baculovirus‐infected insect cells was divided into two phases: a constant viability (or delay) phase characterized by a delay time (td) and a first‐order death phase characterized by a half‐life (t1/2). These two parameters were used in conjunction with the n‐target theory to classify the kinetics of cell death under various conditions, including different multiplicity of infection (MOI), host cell lines, virus types, incubation volumes, cell density and extracellular L(+)‐lactate and ammonium concentrations. Two groups of kinetic effects were found: one characterized by a constant number of hypothetical targets and the other by decreased numbers of hypothetical targets. The first group includes effects such as MOI, virus types, and host cell lines. The second includes the effects of environmental perturbations, such as incubation volume, cell density, and extracellular concentrations of L(+)‐lactate and ammonium. Although the underlying mechanisms of these effects are as yet unknown, the death kinetics of infected cells significantly affects the recombinant protein production. In general, foreign protein production does not correlate with the cell life after infection © 1993 John Wiley & Sons, Inc.
A model of biofilm detachment
Authors: Stewart Philip S. 
Published: December 2004

AbstractA general mathematical framework for modeling biofilm detachment is presented. The approach is founded on a material balance on biomass that equates the detachment rate to the product of a detachment frequency and a detaching particle mass. The model provides a theoretical basis for deriving many of the empirical detachment rate expressions in common use and can thus lend some insight into their physical and biological significance. By allowing for variation in the detachment frequency with depth in the biofilm, the model permits derivation of detachment expressions that reflect a dependence on chemical or physiological gradients in the biofilm. Analysis of literature data sets from two different biofilm systems suggests, in both cases, that detachment is a growth‐associated phenomenon. © 1993 John Wiley & Sons, Inc.
Stability of plasmid vector plJ303 in Streptomyces lividans TK24 during laboratory‐scale fermentations
Authors: Wrigley‐Jones Carys A. , Richards Hilary , Thomas Colin R. , Ward John 
Published: December 2004

AbstractPlasmid plJ303 stability in Streptomyces lividans cultures has been studied by measuring plasmid copy number under various growth conditions. An increase in mean plasmid copy number was normally seen during early rapid growth in both shaken culture and stirred vessel fermentations at 28°C. Maximum copy numbers were consistently attained in early stationary phase followed by a decline (of variable amount) upon further incubation. The imposition of environmental stress (high growth temperature, i.e., 37°C, and low dissolved oxygen tension, i.e., <5% air saturation) led to a plasmid copy number of zero and a 50% reduction, respectively. Interestingly, the relative proportions of plasmid topoisomers changed with time since progressively more supercoiled forms were observed throughout the stationary phase. Plasmid dimers were also observed in some cultures, and no evidence of structural plasmid instability was found. In general, this host‐vector system seemed remarkably stable under normal growth conditions. However, copious organic acid production by the host was observed and was thought to be undesirable for good heterologous gene expression of a secreted protein. © 1993 John Wiley & Sons, Inc.
Yield of poly‐D(‐)‐3‐hydroxybutyrate from various carbon sources: A theoretical study
Authors: Yamane Tsuneo 
Published: December 2004

AbstractThe theoretical yield of poly‐D(‐)‐3‐hydroxybutyrate (PHB) has been estimated from the biochemical pathway leading to PHB when a carbohydrate (glucose), a C1 compound (methanol), a C2 compound (acetic acid), or a C4 compound (butyric acid) is used as a carbon source. In estimating the yield, recycling (or regeneration) of NADP+/ (NADPH + H+) and NAD+ /(NADH + H+) have been taken into account. A special emphasis is made on te regeneration of NADPH, which is the coenzyme of acetoacetyl‐CoA reductase, one of three key enzymes involved in the biosynthesis of PHB. As a NADPH‐regenerating enzyme, glucose‐6‐phosphate dehydrogenase or isocitrate dehydrogenase is conceived. An equation which predicts the overall yield of PHB when non‐PHB residual biomass is actually formed has been derived as a function of both the theoretical yield and PHB content of the dry cell mass. The ratio of the overall yield to the theoretical yield is roughly proportional to the PHB content. © 1993 John Wiley & Sons, Inc.
Measurement of hydrodynamic shear by using a dissolved oxygen probe
Authors: Kim Ik‐Hwan , Cho Moo H. , Wang Shaw S. 
Published: December 2004

AbstractWhen a dissolved oxygen (DO) probe is submerged in an air‐saturated cell culture medium the thickness of the liquid film that exists outside the membrane of a DO probe changes with hydrodynamic shear. The response of the DO probe thus varies with the hydrodynamic shear environment near the DO probe in cell culture reactors. The thickness of the liquid film was estimated by using a three‐layer model, which describes the flow of DO molecules through the liquid layer, the membrane, and the electrolyte, to the cathode of a DO probe. According to the three‐layer model, the current output of the DO probe was a strong function of thickness of the liquid film outside the membrane of the DO probe. A correlation between shear rates on the surface of the probe and the DO saturation reading was obtained by using two concentric cylinders with a rotating inner cylinder. This correlation was then used to characterize the local hydrodynamic shear environment in a cell culture reactor. © 1993 John Wiley & Sons, Inc.
Formation of microparticulate protein powder using a supercritical fluid antisolvent
Authors: Yeo Sang‐Do , Lim Gio‐Bin , Debendetti Pablo G. , Bernstein Howard 
Published: December 2004

AbstractGas antisolvent (GAS) expansion of dimethylsulfoxide (DMSO) and N,N‐dimethylformamide (DMFA) solutions with supercritical carbon dioxide was used to produce biologically active powders of insulin. Powders with 90% of the particles smaller than 4 μm and 10% smaller than 1 μm were obtained under all conditions tested when the process was operated continuously, with small liquid droplets sprayed into a flowing supercritical continuum. Slow pressurization of the stagnant protein solution resulted in larger particles. In vivo tests on rats revealed no differences between the biological activity of processed and unprocessed insulin, GAS processing of organic solution appears to be a reliable and effective method for the production of dry, biologically active microparticulate powders of peptides and proteins. © 1993 John Wiley & Sons, Inc.
Startup of anaerobic fluidized bed reactors with acetic acid as the substrate
Authors: Hsu Yen , Shieh Wen K. 
Published: December 2004

AbstractThe startup of anaerobic fluidized bed reactors, which use Manville R‐633 beads as the growth support media, acetate enriched bacterial culture as the inoculum, and acetic acid as the sole substrate, is studied. Tow startup strategies are evaluated: one based on maximum and stable substrate utilization and another based on maximum substrate loading controlled by reactor pH. The startup process is characterized using a number of operational parameters.The reactors again excellent total organic carbon (TOC) removal (i.e., > 97% at a feed concentration of 5000 mg TOC/L) and stable methane production (i.e., 0.90 L CH4/g TOC, where TOCr is TOC removed) at a early stage of the startup process, regardless of the strategies applied. The loading can be increased rapidly without the danger of being overloaded. Significant losses of growth support media and biomass caused by gas effervescence at higher loadings limits the maximum loading that can be safely applied during startup process.A high reactor immobilized biomass inventory is achievable using the porous growth support media (e.g., Manville 633 beads). A rapid increase in loading creates a substrate rich environment that yields more viable reactor biomass. Both substrate utilization rate (batch and continuous) and immobilized biomass inventory stabilize concomitantly at the late stage of the startup process, indicating the attainment of steady‐state conditions in reactors. Therefore, they are better parameters that TOC removal and methane production for characterizing the entire startup process of aerobic fluidized bed reactor.The strategy based on maximum substrate loading controlled by reactor pH significantly shortens the startup time. In this case, the reactor attains steady‐state conditions approximately 140 days after startup. On the other hand, a startup time of 200 days is required when the strategy based maximum substrate utilization is adopted. © 1993 John Wiley & Sons, Inc.
Application of gravitational sedimentation to efficient cellular recycling in continuous alcoholic fermentation
Authors: Maia Amazile B. R. A. , Nelson David Lee 
Published: December 2004

AbstractA mathematical model for the sedimentation velocity in an inclined parallel plate sedimenter is proposed. The parameters of the alcoholic fermentation broth (cell density of Saccharomyces cerevisiae, density of the fermentation medium, viscosity of the broth at various alcohol and biomass contents) were determined experimentally. The sedimentation velocities were predicted under the various operational conditions and parameters, both of the broth (the alcohol concentration and cell content) and the sedimenter prototype (length, distance between the plates, and slope). The proposed model for the sedimentation velocity presented a good correlation with the experimental results of continuous sedimentation. These sedimenter prototypes were assembled and tested for efficiency of separation of yeast cell under conditions considered for interest for continuous alcoholic fermentation. A selective filter for the overflow composed of calcium alginate gel improved operation. A high operational stability, high separation efficiency (over 98%), and adequate settler residence times (about 20 min) were attained. The operational results permitted the operation of continuous alcoholic fermentation with cellular recycling effected exclusively by gravitational sedimentation, this characterizing a process of enormous industrial interest because of the operational simplicity and low operational and maintenance costs. © 1993 John Wiley & Sons, Inc.
Comparison of substrate utilization and growth kinetics between immobilized and suspended Pseudomonas cells
Authors: Shreve Gina S. , Vogel Timothy M. 
Published: December 2004

AbstractA methodology is described for measurement if immobilized and suspended cell growth and substrate utilization kinetics parameters. Substrate utilization and growth kinetics were compared between immobilized and suspended cells for toluene degrading Pseudomonas strains K3‐2 and 2,4‐dichlorophenoxyacetic acid (2,4‐D) degrading strain DBO131(pR0101), respectively. Kinetic parameters were estimated using nonlinear parameter estimation methods and compared between the immobilized and suspended Pseudomonas cells to determine the effect of immobilization on cellular growth and substrate utilization. Factors influencing the experimental design included calculated oxygen flux rates, primary carbon substrate flux rates, and shear stresses on the immobilize cell. Statistical interpretation of the cellular reaction rate parameters indicates that only the growth kinetics of the toluene system were significantly altered upon immobilization. Substrate utilization kinetics remained unchanged upon immobilization. The substrate growth associated half‐saturation constant (Kg) for the toluene system increased by 30‐fold and the maximum specific growth rate (μmax) decreased by 2‐fold upon immobilization. Implication of these results for experimental determination of cellular kinetic parameters and for immobilization cell bioreactors design are discussed. © 1993 John Wiley & Sons, Inc.
Toward a control of lignin and manganese peroxidases hypersecretion by Phanerochaete chrysosporium in agitated vessels: Evidence of the superiority of pneumatic bioreactors on mechanically agitated bioreactors
Authors: Bonnarme P. , Delattre M. , Drouet H. , Corrieu G. , Asther M. 
Published: December 2004

AbstractPhanerochaete chrysosporium and cultivated both mechanically agitated and pneumatic bioreactors. In the pneumatic devices, the yields of lignin and manganese peroxidases as well as extracellular protein, were considerably increased as compared with mechanically agitated bioreactors. Lignin peroxidase and manganese peroxidase activities as high as 4500 U · L−1 and 1812 U · L−1 respectively, were produced in an airlift bioreactor. By using enzyme markers, the secretion pathway and the respiration were shown to be dramatically activated in pneumatic bioreactors. The general metabolism of the fungus, when cultivated in the conventional fermentors, is oriented toward the synthesis of biomass at the expense of the synthesis of peroxidases. The use of pneumatic devices for the production of extracellular peroxidases by P. chrysosporium, avoids shear effects due to turbine agitator in the conventional fermentors, and provides a good example for the production of shear‐sensitive metabolites. © 1993 John Wiley & Sons, Inc.
Development of an enzyme membrane reactor for treatment of cyanide‐containing wastewaters from the food industry
Authors: Basheer S. , Kut Ö. M. , Prenosil J. E. , Bourne J. R. 
Published: December 2004

AbstractCyanidase, an immobilized enzyme preparation for hydrolyzing cyanide to ammonia and formate, was applied for the treatment of cyanide‐containing waste waters from the food industry. Apricot seed extract was chosen as a model effluent. The enzymatic hydrolysis of pure amygdalin, the main cyanogenic glycoside in the extract, and the degradation of the cyanide formed was investigated and compared with the behavior of the real extract in a batch slurry reactor. A diffusional‐type, flat‐membrane reactor with immobilized cyanidase was developed, where the enzyme is effectively protected from adverse effects of high molecular components contained in the extract. For monitoring continuous‐membrane reactor operation, a new unsegmented ammonia measurement system was developed and applied. In continuous operation the cyanidase retained its original activity for more than 400 hours on steam. © 1993 John Wiley & Sons, Inc.
Enzymatic activity under tangential flow conditions of photochemically grafted membranes containing immobilized catalase
Authors: Selli Elena , D'Ambrosio Andrea , Bellobono Ignazio Renato 
Published: December 2004

AbstractCatalase has been immobilized within sandwich membranes prepared by the photoinduced grafting of an epoxy‐diacrylate prepolymer onto commercial asymmetric cellulose membranes. The enzymatic activity of the membrane composite of hydrogen peroxide decomposition has been studied in a recirculation apparatus under tangential flow conditions without ultrafiltration. The enzymatic membranes were exposed to very low mechanical stresses and showed a very good catalytic performance and durability. Initial reaction rates, measured at 25°C as a function of both substrate concentration and enzyme amount immobilized per unit membrane surface, indicate that the mechanism of action of catalase is not altered after immobilization, although substrate diffusion through the original thin layer of membranes may become rate controlling. © 1993 John Wiley & Sons, Inc.
Enhancement of recombinant protein synthesis and stability via coordinated amino acid addition
Authors: Ramérez Delia M. , Bentley William E. 
Published: December 2004

AbstractIn this work, effective feeding schemes that would minimize stress responses to cloned‐protein overexpression are investigated. The cloned‐protein (chloramphenicolacetyl‐transferase, CAT) contains a high aromatic amino acid content, most notably a high phenylalanine content. Experiments performed on Escherichia coli RR1 [pBR329] (constitutive promoter) and E. coli JM105 [pSH101] (inducible promoter) demonstrated that phenylalanine addition increases the rate of synthesis and yield of CAT. A previous study correlating inducer strength with CAT expression in E. coli JM105 [pSH101] indicated that the highest expression rate was accompanied by the highest apparent rate of protein degradation. In this work, the combined addition of isopropyl‐β‐D‐thiogalactopyranoside (IPTG) and phenylalanine at intermediate levels resulted in substantial increase of CAT synthesis and partial reduction of protein degradation. Furthermore, transmission electron micrographs verified the absence of inclusion bodies, which, along with proteases, were suspected to reduce protein activity. The research demonstrates that significant enhancement in production and stability of heterologous proteins is possible by designing feeding strategies that incorporate knowledge of the interaction between primary cellular metabolism and foreign protein expression. © 1993 John Wiley & Sons, Inc.
Dynamics of phenol degradation by Pseudomonas putida
Authors: Allsop P. J. , Chisti Y. , Moo‐Young M. , Sullivan G. R. 
Published: December 2004

AbstractPure cultures of Pseudomonas putida (ATCC 17484) were grown in continuous culture on phenol at dilution rates of 0.074–0.085 h−1 and subjected to step increases in phenol feed concentration. Three distinct patterns of dynamic response were obtained depending on the size of the step change used: low level, moderate level, or high level. During low level responses no accumulations of phenol or non‐phenol, non‐glucose‐dissolved organic carbon, DOC(NGP), were observed. Moderate level responses were characterized by the transient accumulation of DOC(NGP) with a significant delay prior to phenol leakage. High level responses demonstrated a rapid onset of phenol leakage and no apparent accumulations of DOC(NGP). The addition of phenol to a continuous culture of the same organism on glucose did not result in transient DOC(NGP) accumulations, although transient phenol levels exceeded 90 mg l−1. These results were consistent with intermediate metabolite production during phenol step tests coupled with substrate‐inhibited phenol uptake and suggested that traditional kinetic models based on the Haldane equation may be inadequate for describing the dynamics of phenol degrading systems. © 1993 John Wiley & Sons, Inc.
Criteria to assess when biodegradation is kinetically limited by intraparticle diffusion and sorption
Authors: Chung Gui‐Yung , McCoy Ben J. , Scow Kate M. 
Published: December 2004

AbstractTo determine when intraparticle diffusion and sorption can influence the rate of biodegradation, we consider the biodegradation of a pollutant diffusing into or out of porous aggregates suspended in a liquid medium, where the reactant is metabolized by bacteria. The pollutant that diffuses into the aggregates obeys a sorption–desorption equilibrium isotherm at sites on inner pore surfaces. The governing partial differential equations for the transient process describe (a) the local equilibrium sorption–desorption and the diffusion of the pollutant in the porous aggregate, (b) the mass transfer of the pollutant from the external surface of the spherical aggregates to the reaction medium, and (c) the biodegradation of the pollutant in the external medium. Illustrative calculations are presented for a linear sorption calculations are presented for a linear sorption isotherm and first‐order biodegradation kinetics. A dimensionless group, comprised of the diffusion coefficient, biodegradation rate coefficient, aggregate characteristics length (radius), and adsorption capacity, serves as a criterion for determining when intraparticle diffusion can be ignored. The model provides a realistic description of experimental data for biodegradation of a pollutant subject to intraparticle diffusion and sorption. © 1993 John Wiley & Sons, Inc.