bluuebunny/crossref_metadata_2025_split huggingface dataset:
Storage of solar energy by production of hydrogen peroxide by the blue‐green alga Anacystis nidulans R2: Stimulation by azide
Authors: Morales Inmaculada , Batuecas Santiago , de la Rosa Francisco F. 
Published: December 2004

AbstractThe production of hydrogen peroxide by Anacystis nidulans R2 in presence of methyl viologen occurs by using the redox power from water promoted by the photosystems of the blue‐green alga. Thus, in the presence of the photosynthetic inhibitor DCMU or in the dark, H2O2 production does not take place. In cells permeabilized with lysozyme, the addition of ionophores, which is expected to increase the electron flow, produces only a small increase to initial velocity of hydrogen peroxide production. On the other hand, in nonpermeabilized cells, the addition of superoxide dismutase increases the initial velocity of hydrogen peroxide production, but the net amount accumulated by the system is very low because of posterior decomposition. Preincubation of cells with azide, which inhibits the catalase, prevents the decomposition, thereby increasing drastically the amount of hydrogen peroxide accumulated by the system after a few hours. Hence, H2O2 production appears to be limited mainly because of decomposition by catalase activity rather than by the photosynthetic electron flow rate or the diffusion of products through the cell wall. The net production of hydrogen peroxide by the system was enhanced severalfold by treatment with azide. If one takes into account the use of hydrogen peroxide as fuel due to the large amount of energy released in its dismutation, the photosystem can be a useful tool in the storage of solar energy.
Continuous propionic acid fermentation by immobilized Propionibacterium acidipropionici in a novel packed‐bed bioreactor
Authors: Lewis Vivian P. , Yang Shang‐Tian 
Published: December 2004

AbstractContinuous propionic acid fermentations of lactate by Propionibacterium acidipropionici were studied in spiral wound fibrous bed bioreactors. Cells were imobilized by natural attachment to fiber surfaces and entrapment in the void volume within the fibrous matrix. A high cell density of ∼37 g/L was attained in the reactor and the reactor productivity was ∼4 times higher than that from a conventional batch fermentation. The bioreactor was able to operate continuously for 4 months without encountering any clogging, degeneration, or contamination problems. Also, the reactor could accept low‐nutrient and low‐pH feed without sacrificing much in reactor productivity. This new type of immobilized cell bioreactor is scalable and thus is suitable for industrial production of propionate. © 1992 John Wiley & Sons, Inc.
A kinetic approach to the thermal inactivation of an imobilized triosephosphate isomerase
Authors: Ábrahám Magdolna , Pénzes Zsolt , Szajáani Béla 
Published: December 2004

AbstractThe process of thermal inactivation of triosephosphate isomerase covalently attached to a silica‐based support activated with p‐benzoquinone was found to be a complex one. At 50°C, a characteristic activation preceding the thermal inactivation was observed. Following the intramolecular changes caused by heat, the values of KM and Vmax were determined during the activation. It was presumed that the complex thermal inactivation kinetics reflects the microheterogeneity of the immobilized enzyme molecules. The phosphate ion proved to be a better stabilizer than the substrate. © 1992 John Wiley & Sons, Inc.
Heparin removal from blood using poly(L‐lysine) immobilized hollow fiber
Authors: Ma Xinghang , Mohammad Syed Fazal , Kim Sung Wan 
Published: December 2004

AbstractBased on the negative charge density characteristics of heparin, an affinity adsorption technique has been developed for the removal of heparin from blood. Poly(L‐lysine) · HBr (PLL · HBr), a polycation, was immobilized with the help of cyanogen bromide (BrCN) onto poly(ethylene‐vinyl alcohol) (PEVAL) copolymer coated polyethylene (PE) hollow fibers. Heparin bound rapidly onto PLL · HBr imobilized surface in buffer, plasma, and blood. The heparin binding capacity of PLL immobilized surface increased sevenfold as compared to a non‐PLL‐treated control. When heparinized blood was recirculated through a PLL immobilized PEVAL hollow fiber cartridge, the anticoagulant activity of heparin decreased by 85% from initial activity in 25 min. Moreover, circulation of blood through PLL immobilized hollow fiber did not show any adverse effects; no hemolysis was observed and no significant loss of plasma proteins was noted during the heparin removal process. These results suggest that PLL immobilized surface may be utilized for rapid and effective removal of heparin from blood. © 1992 John Wiley & Sons, Inc.
Optimization of accessible catalase activity in polyacrylamide gel‐immobilized Saccharomyces cerevisiae
Authors: Seip John E. , Di Cosimo Robert 
Published: December 2004

AbstractThe permeabilization of Saccharomyces cerevisiae (baker's yeast), either before or after immobilization in polyacrylamide gel (PAG), has been examined as a means to increase the catalase activity of PAG‐immobilized yeast cells. Prior permeabilization of the cells resulted in large losses of catalase activity during immobilization, but permeabilization after immobilization produced increases in the catalase activity of yeast/PAG particles. A dependence of the accessible catalase activity on the concentration of polyacrylamide in permeabilized yeast/PAG particles, and on the method of permeabilization of the immobilized cells, was observed. Optimal levels of stable catalase activity (1000–2000 IU/g PAG particles; ca. 5%–10% of total available activity) were obtained by immobilizing yeast cells (0.5 g wet cells/mL gel) in 10% (w/v) PAG, followed by permeabilization of the entrapped cells with either cetyltrimethylammonium bromide, Triton X‐100 and one freeze‐thaw, or five freeze‐thaw cycles. © 1992 John Wiley & Sons, Inc.
Hydrocarbon degradation by Acinetobacter calcoaceticus RAG‐1 using the self‐cycling fermentation technique
Authors: Brown Wayne A. , Cooper David G. 
Published: December 2004

AbstractThe use of self‐cycling fermentations (SCFs) as a method for dealing with insoluble carbon substrates was examined. The emulsan‐producing Acinetobacter calcoaceticus RAG‐1 was used as the test organism. Limiting concentrations of hexadecane, 1‐hexadecene, or 1‐chlorohexadecane were used as the carbon substrate. The parameters monitored were residual hydrocarbon concentration, cycle time (doubling time), biomass concentration and emulsan concentration. Cycle‐to‐cycle variations of the measured parameters were found to be samll. In all cases, no residual hydrocarbon was detected. The minimum dissolved oxygen concentration was found to correspond with the complete dissappearance of the carbon source. A correlation between minimum dissolved exygen concentration, biomass concentration, and emulsan concentration was noted, thus making it easy to determine when steady‐state conditions had been reached with respect to biomass and emulsan concentrations. The specific emulsan and biomass yields were found to increase during early stages of the fermentation, attaining their respective maxima at steady‐state. Foaming problems often associated with the complete utilization of the insoluble substrate were eliminated using SCF technology, because harvesting occurs immediately following carbon depletion. From the results, SCFs provide a convenient method by which to produce and harvest emulsan. © 1992 John Wiley & Sons, Inc.
Circular dichroism studies on conformational changes in protein molecules upon adsorption on ultrafine polystyrene particles
Authors: Kondo Akihiko , Murakami Fumiyasu , Higashitani Ko 
Published: December 2004

AbstractThe conformational changes in well‐characterized model proteins [bovine ribonuclease A (RNase A), horseradish peroxidase, sperm‐whole myoglobin, human hemoglobin, and bovine serum albumin (BSA)] upon adsorption on ultrafine polystyrene (PS) particles have been studied using circular dichroism (CD) spectroscopy. These proteins were chosen with special attention to molecular flexibility. The ultrafine PS particles were negatively charged and have average diameters of 20 or 30 nm. Utilization of these ultrafine PS particles makes it possible to apply the CD technique to determine the secondary structure of proteins adsorbed on the PS surface. Effects of protein properties and adsorption conditions on the extent of the changes in the secondary structure of protein molecules upon adsorption on ultrafine PS particles were studied. The CD spectrum changes upon adsorption were significant in the “soft” protein molecules (myoglobin, hemoglobin, and BSA), while they were insingnificant in the “rigid” proteins (RNase A and peroxidase). The soft proteins sustained a marked decrease in α‐helix content upon adsorption. Moreover, the native α‐helix content, which is given as the percentage of the α‐helix content in the free proteins, of adsorbed BSA was found to decrease with decreasing pH and increase with increasing adsorbed amount. These observations confirm some well‐known hypotheses for the confirmational chages in protein molecules upon adsorption. © 1992 John Wiley & Sons, Inc.
Performances of aseptic sampling devices for on‐line monitoring of fermentation processes
Authors: Picque D. , corrieu G. 
Published: December 2004

AbstractTwo liquid sampling systems, which are set in the bioreactor and can be sterilized in place, are described. They are composed primarily of an inorganic membrane filter which is either stationary or is set in a rotating motion. These systems have been tested during three types of fermentation processes (ethanol, lactic acid, and polysaccharide productions). The rotating system gave better filtration performances than the stationary sampler which can be used only in alcoholic fermentation. The rotating sampler was coupled with a high‐pressure liquid chromatograph for the on‐line quantitation of the major compounds present in the filtrate. The results are in good agreement with those obtained from off‐line analysis on samples taken manually. © 1992 John Wiley & Sons, Inc.
Application of polystyrene‐bound invertase to continuous sucrose hydrolysis on pilot scale
Authors: Mansfeld J. , Schellenberger A. , Römbach J. 
Published: December 2004

AbstractInvertase from baker's yeast (Saccharomyces cerevisiae) covalently bound to a macroporous polystyrene anion‐exchange resin via glutaraldehyde was applied to continuous sucrose hydrolysis in packed bed‐reactors. The process was scaled up from 3‐mL laboratory reactors via 0.3‐L reactors to pilot‐scale 50‐L reactors without significant loss of efficiency. The described process allows the production of a wide spectrum of invert sugar syrups with high purity in continuous procedure. The 50‐L reactor was used under process conditions 1 year without significant loss of productivity at a temperature of 40°C. A productivity of 760 g/h was obtained with 1 L invertase–polystyrene complex using a 2.5M sucrose solution as substrate. © 1992 John Wiley & Sons, Inc.
Preparation and application of poly(vinylamine)/alginate microcapsules to culturing of a mouse erythroleukemia cell line
Authors: Wang F. F. , Wu C. R. , Wang Y. J. 
Published: December 2004

AbstractPoly(vinylamine) was synthesized and used to replace poly‐L‐lysine in forming microcapsule with alginate. Test results indicated that capsules with good mechanical strength and permeability could be obtained under the controlled treatment conditions of poly(vinylamine) and alginate. Application of the current microcapsular system to cell culture was demonstrated by the usage of erythropoietin‐ (EPO‐) producing IW32 mouse erythroleukemia cells. The encapsulated IW32 cells grew to a density of 8 × 107 cells/mL, two times that found in the corresponding poly‐L‐lysine/alginate capsules. The EPO accumulation inside the microcapsule with the current encapsulation system was also higher. A concentration of 7.3 U/mL was attained as compared to 4.3 U/mL in the poly‐L‐lysine/alginate microcapsule. © 1992 John Wiley & Sons, Inc.
Productivity of outdoor algal cultures in enclosed tubular photobioreactor
Authors: Lee Yuan‐Kun , Low Chin‐Seng 
Published: December 2004

AbstractAt quasi‐steady‐state outdoor cyclic fed batch cultures of Chlorella pyrenoidosa, the growth irradiance incidented on the tubular photobioreactor increased about fivefold between 9:00 a.m. and noon. Overheating of the cultures was observed, resulting in decreasing biomass output rate when culture temperature went above 40°C. In cultures with temperature control, the quasi‐steady‐state output rate of all cultures increased throughout the day and leveled off in the late afternoon in high‐density cultures. The daily area output rate was proportional to the density of the cultures. The specific growth rate of the light‐limited cultures increased only marginally (20%) in the morning. © 1992 John Wiley & Sons, Inc.
Methanotrophic attached‐film reactor development and biofilm characteristics
Authors: Fennell Donna E. , Underhill Shelia E. , Jewell William J. 
Published: December 2004

AbstractThe feasibility of using methanotrophs in an attached‐film, fluidized‐bed (MAFFB) reactor system has been under investigation since 1987. Mixed culture, methane‐utilizing attached biofilms were developed on diatomaceous earth particles and on granular activated carbon. The required feed gases, methane and oxygen, were supplied to the attached biofilm in disolved form using separate gas–liquid aeration columns. Biofilm growth was steady despite low influent dissolved methane concentrations (1 to 3 mg/L). A breeder MAFFB operated consistently for 4.1 years with attached biofilm concentrations as high as 51.7 g VS/L static‐bed with minimal biomass wasting and with minimal buffer and nutrient inputs. The maximum biomass concentration observed was 75.6 g VS/L static‐bed in a MAFFB reactor treating trichloroethene. Biofilm thickness reached 160 μm with typical values of 70 μm under methane and oxygen growht‐rate–limited conditions. Biofilm densities of 120 to 190 g VS/L film were observed. Growth rates varied from <0.01/d to 0.17/d. Greater than 90% of the biomass concentration in the bed was attached, and effluent total suspended solids ranged from 5 to 74 mg/L, with an average of 24 mg/L over 27 runs in four MAFFB systems at upflow velocities of 11.4 to 25 m/h. Heterotrophic attached‐film methanotrophs appear to be stable and useful for applications in toxics treatment, and other product manipulations. © 1992 John Wiley & Sons, Inc.
Physical modeling of animal cell damage by hydrodynamic forces in suspension cultures
Authors: Lu George Z. , Gray Murray R. , Thompson B. G. 
Published: December 2004

AbstractPhysical damage of animal cells in suspension culture, due to stirring and sparging, is coupled with complex metabolic responses. Nylon microcapsules, therefore, were used as a physical model to study the mechanisms of damage in a stirred bioreactor and in a bubble column. Microcapsule breaskage folowed first‐order kinetices in all experiments Entrainment of bubbles into the liquid phase in the stirred bioreactor gave more microcapsule breakage. In the bubble column, the bubble bursting zone at gas–liquid interface was primarilu responsible for microcapsule breakage. The forces on the microcapsules were equivalent to an external pressure of approximately 4 × 104 N · m−2, based on the critical microcapsule diameter for survival of 190 μm. A stable foam layer, however, was found to be effective in protecting microcapsules from damage. The microcapsule transport to the gas–liquid interface and entrainment into the foam phase was consistent with flotation by air bubbles. This result implies that additives and operation of bioreactors should be selected to minimize flotation of cells. © 1992 John Wiley & Sons, Inc.
Improved activity retention of enzymes deposited on solid supports
Authors: Wehtje Ernst , Adlercreutz Patrick , Mattiasson Bo 
Published: December 2004

AbstractEnzymes deposited on solid support usually show good stability when operated in organic solvents. Decreased stability of the enzyme preparations was noticed when low enzyme loadings were used (e.g., with Celite as support; less than 1 mg enzyme/g). It was possible to avoid the activity loss by the addition of an additive which protects the enzyme during the immobilization. Proteins (such as albumin, gelatin, and casein) and poly(ethylene glycol) were effective additives whereas amino acids, monomeric carbohydrates, and polysaccharides had no effect. The amount of additive needed for stabilization was shown to depend on the structure of the support, more additive being required for a support with high porosity. The stabilizing effect was investigated in a series of glyceryl‐controlled‐pore glass (CPG) with varying specific surface areas (9.5–180 m2/g). The minimum addition of albumin, giving full stabilization, on the different supports correlated to a monolayer coverage of the surface, approximately 2–3 mg protein/m2. The effect of the additive was less pronounced when increasing amounts of enzyme were immobilized (5–40 mg enzyme/g Celite). The effect of the additives was studied using mandelonitrile lyase, but α‐chymotrypsin and lipase P were also shown to be stabilized. © 1993 John Wiley & Sons, Inc.
Kinetics of cell growth and heterologous glucoamylase production in recombinant Aspergillus nidulans
Authors: Lin Weng‐Long , Felberg Ross S. , De Bernardez Clark Eliana 
Published: December 2004

AbstractIn the work, a study of cell growth and the regulation of heterologous glucoamylase synthesis under the control of the positively regulated alcA promoter in a recombinant Aspergillus nidulans is presented. We found that similar growth rates were obtained for both the host and recombinant cells when either glucose or fructose was employed as sole carbon and energy source. Use of the potent inducer cyclopentanone in concentrations greater than 3 mM resulted n maximum glucoamylase concentration and maximum overall specific glucoamylase concentration over 80 h of batch cultivation. However, cyclopentanone concentrations in excess of 3 mM also showed an inhibitory effect on spore germination as well as fungal growth. In contrast, another inducer, threonine, had no negative effect on spore germination even when concentrations of up to 100 mM were used with either glucose or fructose as carbon source. Glucoamylase synthesis in the presence of glucose plus either inducer did not begin until glucose was totally depleted, suggesting strong catabolite repression. Similar results were obtained when fructose was employed, although low levels of glucoamylase were detected before fructose depletion, suggesting partial catabolite repression. The highest enzyme concentration (570 mg/L) and overall specific enzyme concentration (81 mg/g cell) were observed in batch culture when cyclopentanone was the inducer and fructose the primary carbon source. A maximum glucoamylase concentration of 1.1 g/L and an overall specific glucoamylase concentration of 167 mg/g cell were obtained in a bioreactor using cyclopentanone as the inducer and limited‐fructose feeding strategy, which nearly doubles the glucoamylase productivity from batch cultures. © 1993 John Wiley & Sons, Inc.
Production of cellobiose by enzymatic hydrolysis: Removal of β‐glucosidase from cellulase by affinity precipitation using chitosan
Authors: Homma Taira , Fujii Michihiro , Mori Jun‐ichi , Kawakami Tohru , Kuroda Kenji , Taniguchi Masayuki 
Published: December 2004

AbstractRemoval of β‐glucosidase (BG) from cellulase is essential to the enzymatic production of cellobiose from cellulose because of the high reactivity of BG with cellobiose to form glucose. Chitosan is a reversibly soluble‐insoluble polymer depending on pH, and it has an affinity with the other components, endo‐β‐1,4‐glucanase and cellobiohydrolase, or cellulase. The affinity precipitation technique using chitosan is an effective way to fractionate cellulase for the above purpose. Hydrolysis experiments of cellulose with the residual fractionated enzyme gave higher cellobiose contents in the soluble sugar products. © 1993 John Wiley & Sons, Inc.
Biofiltration of methanol vapor
Authors: Shareefdeen Zarook , Baltzis Basil C. , Oh Young‐Sook , Bartha Richard 
Published: December 2004

AbstractBiofiltration of solvent and fuel vapors may offer a costeffective way to comply with increasingly strict air emission standards. An important step in the development of this technology is to derive and validate mathematical models of the biofiltration process for predictive and scaleup calculations. For the study of methanol vapor biofiltration, an 8‐membered bacterial consortium was obtained from methanol‐exposed soil. The bacteria were immobilized on solid support and packed into a 5‐cm‐diameter, 60‐cm‐high column provided with appropriate flowmeters and sampling ports. The solid support was prepared by mixing two volumes of peat with three volumes of perlite particles (i.e., peat–perlite volume ratio 2:3). Two series of experiments were performed. In the first, the inlet methanol concentration was kept constant while the superficial air velocity was varied from run to run. In the second series, the air flow rate (velocity) was kept constant while the inlet methanol concentration was varied. The unit proved effective in removing methanol at rates up to 112.8 g h−1 m−3 packing. A mathematical model has been derived and validated. The model described and predicted experimental results closely. Both experimental data and model predictions suggest that the methanol biofiltration process was limited by oxygen diffusion and methanol degradation kinetics. © 1993 John Wiley & Sons, Inc.
Catalytic and interfacial aspects of enzymatic polymer synthesis in reversed micellar systems
Authors: Rao A. Madhusudhan , John Vijay T. , Gonzalez Richard D. , Akkara Joseph A. , Kaplan David L. 
Published: December 2004

AbstractThe enzyme horseradish peroxidase, when encapsulated in reversed micelles, is capable of catalyzing the synthesis of phenolic and aromatic amine polymers. The synthesis of polyethylphenol is specifically considered in this article and is found to be extremely feasible in the micellar system. Polymer chain growth can be controlled to some degree by manipulating the ability of the solvent to sustain chain solubility; this is effectively done by adjusting the surfactant concentration. This results in a degree of control of polymer molecular weight. The synthesized polymer drops out of solution and can be easily recovered. © 1993 John Wiley & Sons, Inc.
Optimization of fed‐batch fermentors by iterative dynamic programming
Authors: Luus Rein 
Published: December 2004

AbstractBy using penalty functions to handle state constraints, iterative dynamic programming can be used in a straightforward manner for the optimization of fedbatch fermentors. No computational difficulties were encountered and better results are obtained than previously reported in the literature for a fed‐batch fermentor for biosynthesis of penicillin. © 1993 Johy Wiley & Sons, Inc.