bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immobilization of BSA, enzymes and cells of Bacillus stearothermophilus onto cellulose, polygalacturonic acid and starch based graft copolymers containing maleic anhydride
Authors: Beddows C. G. , Gil M. H. , Guthrie J. T. 
Published: December 2004

AbstractPoly(maleic anhydride styrene) graft copolymers of cellulose, pectin polygalacturonic acid salt, calcium polygalacturonate, and starch were prepared and used to immobilize proteins. The cellulose grafts coupled quite appreciable quantities of acid phosphatase, glucose oxidase, and trypsin. However, the general retention of activity was somewhat disappointing. Further investigation with acid phosphatase showed that the amount of enzyme immobilized increased as the amount of anhydride in the graft copolymer increased but no such relationship existed for the enzymic activity. The cellulose graft copolymers were hydrolyzed and it appeared that the carboxyl group aided adsorption of the enzyme. Attempts to couple acid phosphatase using CMC through the free carboxyl groups, created by hydrolysis, gave only a small increase in the extent of protein coupling. However, the unhydrolyzed system gave a useful degree of immobilization of cells of Bacillus stearothermophilus, as did a poly(maleic anhydride/styrene)‐cocellulose system. Attempts to improve the activity by using grafts based on other polysaccharide supports met with mixed success. Pectin products were soluble. Polygalacturonic acid products were partially soluble and extremely high levels of enzymic activity were obtained. This was probably due in part to the hydrophilic nature of the system, which also encouraged absorption of the enzyme. Attempts were made to reduce the solubility by using the calcium pectinate salt. Immobilization of acid phosphatase and trypsin resulted in inceased protein coupling but relatively poor activities were attained. A starch based system gave similar results. Calcium polygalacturonate was used to prepare an insoluble graft copolymeric system containing acrylonitrile‐comaleic anhydride. The resulting gels gave excellent coupling with acid phosphatase which had a very good retention of activity.
Parameters affecting optimum activity and stability of urokinase‐bound fibrocollagenous tubes
Authors: Senatore Fred , Bernath Fred 
Published: December 2004

AbstractUrokinase was immobilized by entrapment to fibrocollagenous tubes in order to develop a small‐caliber fibrinolytic vascular prosthesis. Several parameters associated with the immobilization process were studied in order to optimize bound urokinase activity and stability. A total of 37% of the absorbing enzyme was attached to the collagen tube and 38% of the attached enzyme retained esterolytic activity, under optimal conditions. In the crosslink step of the entrapment process, the glutaraldehyde concentration was varied from 0.01 to 5.00% (i.e., 0.01, 0.1, 1.0, 3.0, and 5.0%). Urokinase activity was optimized at a 1.0% glutaraldehyde crosslink concentration. Urokinase‐bound fibrocollagenous tubes (UK‐FCT) prepared at the above glutaraldehyde concentrations were tested for their activity with time. The UK‐FCT's with 0.1, 1.0, and 3.0% glutaraldehyde retained constant activity for at least 75 h operation time. The UK‐FCT's with 0.1, 1.0, and 3.0% glutaraldehyde retained constant activity for at least 75 h operation time. The UK‐FCT's with 5.0 and 0.01% glutaraldehyde remained stable for the first 50 h operation time, but begandeactivating beyond 50 h. UK‐FCT'S Crosslinked with 0.01, 0.1, 1.0, and 5.0% glutaraldehyde were recrosslinked with 0.02% glutaraldehyde for 24 h, after they have been operating for 50 h, and the effect of reexposing the crosslink agent on the stability of the UK‐FCT's was studied. The results showed that 0.02% glutaraldehyde reexposure had no effect on 0.1, 1.0, and 5.0% glutaraldehyde crosslinked UK‐FCT's but exerted an inhibitory effect on a 0.01% crosslink density UK‐FCT. Several fibrocollagenous tubes were exposed to various glutaraldehyde concentrations prior to immobilizing urokinase. The subsequent immobilization process occurred under optimal conditions. The effect of the precrosslink step on the activity of the UK‐FCT was studied. Results indicated that UK‐FCT activity decreases as the precrosslink density increases. The UK‐FCT's made under optimal conditions remained stable for at least 75 h operation time, corresponding to ca.1 year of storage time. Ex vivo exposure of UK‐FCT's to whole canine blood did not affect catalytic activity. Implantation of a UK‐FCT by carotid arterial interposition via an end‐to‐end anastomosis and subsequent excision after 60 days resulted in an enhanced esterolytic activity which decreased with time to a level close to preoperative levels.
Patterns of aeration in a solid substrate fermentor through the study of the residence time distribution (RTD) of a volatile tracer
Authors: Gervais Patrick , Bazelin Christophe , Voilley Andrée 
Published: December 2004

AbstractThe injection of a volatile tracer in the gas flow allowed to describe the residence time distribution (RTD) in a solid substrate reactor. The chromatographic analysis of Dirac impulses of acetone led to identify the fermentor as a first‐order rate system. The evolution of the time constant (λ) of the system versus the gas flow rate gave a flow rate value that permitted a homogeneous aeration of the fermentor.
Fabrication of reusable enzyme brushes for clinical analyses: Lactate dehydrogenase enzyme brush
Authors: Raghavan K. G. , Ramakrishnan V. 
Published: December 2004

AbstractA simple procedure for the entrapment of enzymes in nylon‐reinforced cellulose triacetate fibers and the fabrication of reusable enzyme brushes using such fiber bristles for the analytical determination of unknown samples have been described. As an example, enzyme brushes of lactate dehydrogenase were fabricated and were repeatedly employed for the determination of pyruvic acid in clinical samples in place of soluble enzymes. The above brush method compared well with that of wet enzymic analysis of pyruvate in clinical samples in accuracy, sensitivity, and reproducibility. The device also proved to be easy to handle, use, and reprocess for repeated analyses.
Deactivation of free and stabilized acid phosphatase by urea
Authors: Gianfreda Liliana , Marrucci Giuseppe , Greco Guido 
Published: December 2004

AbstractTests on acid phosphatase (E.G. 3.1.3.2) deactivation by urea have been performed at two pH values. Two conditions have been used: native enzyme operating batch‐wise in dilute solution and stabilized enzyme in continuous flow ultrafiltration membrane reactor. Stabilization is achieved by confining the enzyme within a concentrated solution of a linear chain polymer that forms a polarization layer over the membrane. The results provide significant information on the kinetics and thermodynamics of the complex phenomena taking place during deactivation. Deactivation by urea is also compared with thermal deactivation.
Depolymerization of chondroitin C Sulfate by immobilized Proteus vulgaris cells
Authors: Sato Nobuyuki , Murata Kousaku , Kimura Akira 
Published: December 2004

AbstractChondroitinase ABC catalyzing the depolymerization of chondroitin sulfate was induced by incubating the Proteus vulgaris cells in a medium containing chondroitin C sulfate as an inducer. Incubation of P. vulgaris cells for 12 h in the presence of 0.3% inducer was optimal to obtain the cells with highly active chondroitinase ABC. Such cells were immobilized in k‐carrageenan gel lattice, and some properties of chondroitinase ABC in immobilized cells were studied in comparison with those of the enzyme without immobilization (free enzyme). The stabilities of the enzyme toward heat and storage were remarkably improved by immobilizing the cells in k‐carrageenan gel lattice. Optimal pH and temperature for activity of the enzyme were slightly shifted to the alkaline region and higher temperature by immobilization and were 9.0 and 35°C, respectively.
A method for estimating the rejection coefficient–molecular weight relationship of ultrafiltration membrane for a chain polymer by using gel permeation chromatography
Authors: Adachi Shuji , Hashimoto Kenji , Komoto Mitsuaki , Tobita Hidetaka 
Published: December 2004

AbstractAn improved method is presented for estimating rejection coefficient‐molecular weight relationship of an ultrafiltration membrane for a polydisperse chain polymer. It is based on the basic idea using gel permeation chromatography originally developed by Cooper and Van Derveer. The method, in which peak spreading of an elution curve of the polymer was taken into consideration, is available for evaluating the relationship over a wide range of the molecular weight through only one experiment in analyses of the retentate and filtrate.
Growth dynamics of a methylotroph (Methylomonas L3) in continuous cultures. I. Fast transients induced by methanol pulses and methanol accumulation
Authors: Chu I‐Ming , Papoutsakis Eleftherios Terry 
Published: December 2004

AbstractThe dynamic behavior of the Ribulose Monophosphate‐type Methylomonas L3 in continuous cultures was studied, using methanol pulses to induce fast transients in steady‐state cultures of single (methanol) and mixed (methanol plus formaldehyde) substrates. In several experiments, the methanol‐uptake rate (MUR) profiles displayed negative MUR values for a time period following the methanol pulse, and significant amounts of methanol disappeared immediately following the pulse. These phenomena suggested the accumulation of methanol in the cells upon pulsing, apparently due to an active transport system. Accordingly, and in order to estimate the potential of the transport system for methanol accumulation, accumulation profiles were calculated for several pulse experiments. The calculations are based on a methanol balance and experimentally determined values of the cell volume and the true transient biomass yields. It is calculated that methanol accumulates up to 200‐fold to very high intracellular concentrations. The accumulation is calculated to be much higher in single‐ (methanol) substrate cultures of low dilution rate than in cultures of high dilution rate or of mixed substrates. The specific growth rate immediately following the methanol pulse decreased in single‐substrate cultures and increased in mixed‐substrate ones. The biomass yield decreased after the methanol addition in all experiments; however, the drop was less severe in the mixed‐substrate experiments. It is also suggested that formaldehyde as a methanol cosubstrate may be an effective means of providing more stable biomass yields and growth rates in reactors with imperfect mixing, and of protecting the reactor against accidentally induced methanol accumulation.
Properties and principles of mycelial flow: Experiments with a tube rheometer
Authors: Björkman Ulf 
Published: December 2004

AbstractThe flow behavior of a penicillin mash has been investigated with a tube rheometer and compared with rotational viscometer observations. In the low‐shear regions plug flow and breakdown of the plug have been studied. For turbulent flow turbulence damping was demonstrated. The Theological development during the fermentation was followed. At low deformation rates the pressure drop increased during the fermentation. In turbulent regions the opposite tendency was observed. The possible underlying flow mechanisms are discussed, and the influence of a number of physical parameters have been investigated.
Bioactive polymers XXX. Immobilization of invertase on the diazonium salt of 4‐aminobenzoylcellulose
Authors: Simionescu Cristofor , Popa Marcel I. , Dumitriu Severian 
Published: December 2004

AbstractInvertase was immobilized on diazotized 4‐aminobenzoylcellulose. The optimum coupling conditions, namely enzyme concentration, time, and pH, were determined. The temperature and pH value for the maximum activity of the immobilized enzyme were determined and the apparent Michaelis constant was estimated.
Mathematical modeling of ethanol production by immobilized Zymomonas mobilis in a packed bed fermenter
Authors: Melick Michael R. , Karim M. N. , Linden J. C. , Dale B. E. , Mihaltz Pal 
Published: December 2004

AbstractA mathematical model which describes ethanol production in a packed bed fermenter containing. Zymomonas mobilis entrapped in small spheres of calcium alginate within a packed bed fermenter has been developed. The equations combine simultaneous diffusion and reaction as well as a complex flow pattern to calculate glucose and ethanol profiles in the column type reactor. As part of the study, diffusivity values for glucose and ethanol in cell‐loaded calcium alginate were determined. Also a freecell kinetic expression for Z. mobilis at 33°C and ph 6.0 was developed. Comparison of the model with actual experimental results were made showing average deviations of ca. 30–40%.
Feasibility of enzymatic hydrolysis and alcoholic fermentation of starch contained in buffalo gourd (Cucurbita foetidissima) roots
Authors: Scheerens J. C. , kopplin M. J. , Abbas I. R. , Nelson J. M. , Gathman A. C. , Berry J. W. 
Published: December 2004

AbstractThe suitability of using annually grown, carrot‐sized buffalo gourd (Cucurbita foetidissima) roots as a feedstock for alcoholic fermentation was explored. Roots grown in 1982 and 1983 were slurried, dextrinized and saccharified using Takatherm™ and Diazyme™ (commercial enzymes manufactured by Miles Laboratories), and fermented by the action of Saccharomyces cerevisiae. These processes were monitored in detail and results were compared with those displayed by controls formulated using potato tubers. The preparation of gourd root slurries with suitable viscosity characteristics for enzymatic digestion required the addition of water (at least 50% by weight) which reduced the proportion of fermentable sugars in the resulting saccharified suspensions. The resulting slurries were well‐suited to enzymatic conversion of starch to sugar. Estimates of enzymatic efficiency in gourd root suspensions did not suggest the presence of naturally occurring amylase or glucosidase inhibitors in these plant materials. Saccharified gourd root mashes supported yeast growth well and produced ethanol yields at 82.2–86.5% of the theoretically maximum efficiency.
Fermentation kinetics of Zymomonas mobilis near zero growth rate
Authors: Jöbses I. M. L. , Hiemstra H. C. H. , Roels J. A. 
Published: December 2004

AbstractThe fermentation kinetics Zymomonas mobilis were studied near zero growth rate in fed‐batch cultures and continuous cultures with complete cell recycle. The results show the ethanol enhances that specific substrate conversion rate under these conditions. The maximum achievable ethanol concentration in continuous cultures with cell recycle (66 g/L) was significantly lower than in fed‐batch cultures (100 g/L). The results indicate that growth‐rate‐independent metabolism is not instantaneous and can lag behind steadily increasing ethanol concentrations in fed‐batch fermentations. A model is proposed to account for this slow adaptation.
Factors affecting the photoproduction of ammonia from dinitrogen and water by the cyanobacterium Anabaena sp. strain ATCC 33047
Authors: Ramos Juan L. , Guerrero Miguel G , Losada Manuel 
Published: December 2004

AbstractSynthesis of ammonia from dinitrogen and water by suspensions of Anabaena sp. Strain ATCC 33047 treated with the glutamine synthetase inhibitor L‐methionine‐D,L‐sulfoximine is strictly dependent on light. Under otherwise optimal conditions, the yield of ammonia production is influenced by irradiance, as well as by the density, depth, and turbulence of the cell suspension. The interaction among these factors seems to determine the actual amount of light available to each single cell or filament in the suspension for the photoproduction process. Under convenient illumination, the limiting factor in the synthesis of ammonia seems to be the cellular nitrogenase activity level, but under limiting light conditions the limiting factor could, however, be the assimilatory power required for nitrogen fixation. Photosynthetic ammonia production from atmospheric nitrogen and water can operate with an efficiency of ca. 10% of its theoretical maximum, representing a remarkable process for the conversion of light energy into chemical energy.
The macrokinetic behavior of an enzymatic system with an enzyme inactivated in the reaction
Authors: Sud'ina G. F. , Kobel'kov G. M. , Varfolomeev S. D 
Published: December 2004

AbstractThis study deals with the behavior of a heterogeneous multisubstrate enzymatic system under enzyme inactivation in a reaction. Electronic computer modeling data have been obtained for its macrokinetics at different modes: (1) under mixed inflow of the substrates and (2) under their spatial separation. The enzymatic membrane exhibits low sensitivity to a change in the external conditions as the substrates are intermixed on the boundary. Quite the contrary, in the case of spatial separation of the substrates, the product flow from the membrane has displayed abrupt fluctuations at different boundary conditions. This work also looks into the arrangement of the reaction zones in the membrane and their transitions under different conditions.
Effect of cycling on final mixed culture fate
Authors: Stephens M. L. , Lyberatos G. 
Published: December 2004

AbstractCycling in feed substrate concentration and dilution rate is examined as a means of modifying the final fate of a mixed culture. It is shown for the case where the specific growth rate of one species is always greater than that of the second that no cycling strategy will provide the desired extinction of the faster growing species unless time delay is included in the modeling. To account for the time lag in adjusting organism metabolic activities to environmental changes, an adaptability parameter is introduced. Numerical simulations are carried out and an operating diagram indicating the conditions under which the desired extinction occurs is constructed. Cycling in feed substrate concentration and dilution rate are both found to produce the desired result.
The influence of immobilization and reduced water activity on gaseous‐alkene oxidation by Mycobacterium PY1 and Xanthobacter PY2 in a gas–solid bioreactor
Authors: Hamstra R. S. , Murris M. R. , Tramper J. 
Published: December 2004

AbstractImmobilization of Mycobacterium PY1 and Xanthobacter PY2 in alginate and in or on hydroculture has a minor influence on the maximum rate of oxidation of propene and ethane. The apparent Km values of the immobilized cells are slightly higher than those of the free cells, indicating the presence of diffusion limitation in the immobilized systems. Both bacterial strains rapidly lose their alkene‐oxidizing activity when the water activity is decreased. This decrease in activity is so rapid that most of the activity is lost already when the pores of the pertinent supports are still filled with water. Therefore, it is not possible with this system to study the transition of mass transfer of substrates entirely in the water phase to mass transfer to substrates entirely through the gas phase.
Analysis of two interacting bacterial populations with opposite substrate preferences
Authors: Kim Sun Uk , Dhurjati Prasad 
Published: December 2004

AbstractInteractions between two bacterial species which exhibit opposite substrate preferences in response to the same environmental conditions were investigated. Klebsiella oxytoca preferentially utilizes glucose over citrate as a substrate while Pseudomonas aeruginosa utilizes citrate over glucose. Both species were grown on single as well as mixed substrates, namely, D‐glucose and citrate, with various ratios of inocula and substrates. Competition is observed between the two species with citrate alone while amensalism is observed with glucose alone. In mixed cultures‐mixed substrates experiments, amensalism of K. oxytoca on P. aeruginosa prevailed until the exhaustion of glucose.
Some observations on the role of type 1 fimbriae in Escherichia coli autoflocculation
Authors: Goochee Charles F. , Hatch Randolph T. , Cadman Theodore W. 
Published: December 2004

AbstractTechniques are reviewed for the identification and enrichment of fimbriae‐positive and fimbriae‐negative Escherichia coli. Fimbriae‐positive E. coli were observed to form a semistable suspension of pH 7.0 which settled at a rate much slower than the fimbriae‐negative bacteria. Intense autoflocculation of fimbriae‐positive E. coli was noted at pH values below 5.2.
Enzymic interesterification of fats: Laboratory and pilot‐scale studies with immobilized lipase from Rhizopus arrhizus
Authors: Wisdom R. A. , Dunnill P. , Lilly M. D. 
Published: December 2004

AbstractAn immobilized lipase suitable for fat interesterification has been prepared by precipitation with acetone of a commercial lipase from Rhizopus arrhizus onto diatomaceous earth. As observed previously with a less active enzyme from Aspergillus sp., the interesterification activity was enhanced by addition of purified lipase or by high loadings of commercial enzyme. The interesterification activities reached maximum values in both cases. For immobilized preparations with purified enzyme, interesterification activity was also enhanced by the presence of a precoat of glutaraldehyde cross‐linked commercial lipase. A 2.9‐L column of immobilized lipase was used to interesterify batches of shea oleine (67 kg) and shea oil (40 kg). Little activity was lost processing shea oleine, but slow poisoning of the bed occurred when shea oil was fed to the column.
Geometrical design of immobilized cell modular units for ethanol fermentation
Authors: Bourassa Jean‐François , LeDuy Anh 
Published: December 2004

AbstractFormula are developed for calculating the performance characteristics (surface‐to‐total‐volume ratio, surface‐to‐packing‐volume ratio, and void volume fraction) of four different types of immobilized cell modular units (ICMUs) for ethanol fermentation: plate‐type, spiral‐type, beehive‐type and bead‐type ICMUs. Examples are used to illustrate how the formulas are useful for investigating the effects of characteristic dimensions of packing geometry, as well as the effect of scale on the performance characteristics of the ICMUs.
Attachment and growth of mammalian cells on microcarriers with different ion exchange capacities
Authors: Himes Vaughn B. , Hu Wei‐Shou 
Published: December 2004

AbstractIn the design of microcarriers for animal cell growth, the exchange capacity has been considered a critical factor. However, charge densities of microcarriers under culture conditions are not the same as the exchange capacities. Furthermore, the charge density requirement for optimum attachment is not necessarily the same as that required for optimum growth. We demonstrate that charge is not the sole factor affecting the attachment and growth of animal cells on microcarriers. We also show that supplemental serum in the growth medium has a negative effect on cell attachment to microcarriers.
Growth kinetics of Eschericia coli containing temperature‐sensitive plasmid pOU140
Authors: Betenbaugh Michael J. , diPasquantonio Vincent M. , Dhurjati Prasad 
Published: December 2004

AbstractThe growth dynamics of Escherichia coli with the temperature‐sensitive plasmid, pOU140, were examined. Recombinant cells exhibited nearly identical kinetic behavior to host cells at low culture temperatures and low copy numbers. However, at higher temperatures, in which the copy number was significantly increased, the recombinant cells showed decreased stability along with lower growth rates and substrate yields as compared to the host. Furthermore, the production of a constitutive cloned‐gene protein was shown to increase with temperature in an Arrhenius fashion when culture temperature was varied between 38 and 42°C. These results suggest that temperature can be used to quantitatively control the production of a desirable plasmid‐coded gene product.