bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical evaluation of glucose oxidase immobilized by different methods
Authors: Lahoda E. J. , Liu C. C. , Wingard L. B. 
Published: December 2004

AbstractGlucose oxidase electrodes were constructed on a platinum screen using polyacrylamide gel, glutaraldehyde crosslinking, and glutaraldehyde crosslinking with +0.04 volts dc on the platinum screen as the methods of enzyme immobilization. The electrodes were evaluated in an electrochemical cell for the oxidation of glucose at the enzyme electrode and the reduction of oxygen at a platinum auxiliary electrode, using constant current voltametry or under external load operation. The method of immobilization affected the extrapolated opencircuit potential as well as the half‐cell potential and the steady current under external load operation. The charged glutaraldehyde electrode gave the best current performance; however, the small output (microamps) indicated that major problems in electron transfer from an enzyme catalyst to an external circuit must be resolved before such electrodes can be used in practical application.
Sucrose inversion by immobilized yeast cells in a complete mixing reactor
Authors: Toda K. , Shoda M. 
Published: December 2004

AbstractUsing whole cell invertase of Saccharomyces pastorianus, entrapped in spherical agar pellets, sucrose hydrolysis was carried out in a continuously fed fluidized bed reactor. The effective rate of reaction determined experimentally for the catalytic pellet was correlated with particle radius (R), intraparticle concentration of enzyme (Ep) and external concentration of substrate (SR).The results were elucidated by theoretical analysis incorporating internal mass transfer resistance. At high degrees of diffusional resistance, the effectiveness factor was successfully estimted from Bischoff's equation. A dimensionless number, mA  R(k2Ep/KmD)0.5(Km/(Km + SR)), was used conveniently to predict the effectiveness factor in those cases wher the intraparticle diffusional effect was less significant. This number was employed to determine critical pellet size for an optimal reaction.The relationship between the properties of the pellet (size and intraparticle enzyme activity) and its apparent kinetic constants (k′2 and K′m), estimated according to Lineweaver‐Burk, are discussed.
Dynamic response of a polarographic oxygen probe
Authors: Kok R. , Zajic J. E 
Published: December 2004

AbstractThe dynamic characteristic of dissolved oxygen probes is usually modeled as being equivalent to a single diffusion layer. Other workers have shown that in response to a downstep in oxygen tension a polarographic probe initially follows single diffusion layer dynamics but that during the last 10% of response the probe deviates significantly from this behavior.Probe response to a series of downsteps of various magnitudes after exposure to calibration gases for 1, 2, and 3 min was recorded. When the probe membrane was new the response behavior was found to be largely independent of the step size as well as the exposure duration.The deviation fro the single diffusion layer model was explained in terms of lateral diffusion of oxygen from the anodic compartment to the cathode. By use of a model incorporating the lateral diffusion, probe response to a general oxygen tension‐time function was calculated.
Using multiresponse data to estimate biokinetic parameters
Authors: Johnson David B. , Berthouex Paul M. 
Published: December 2004

AbstractBiokinetic parameters are usually calculated from slopes and intercepts taken from plots of experimental data. One response at an item is plotted and used for parameter estimation. Aside from problems that may be caused by transformations made when the data are plotted, this approach has the weakness of not using all the data simultaneously when there is more than one response. This paper shows how multiresponse biological data can be handled to get parameter estimates that are much more precise than those obtained using conventional methods.
Continuous coagulation of milk using immobilized enzymes in a fluidized‐bed reactor
Authors: Cheryan M. , Van Wyk P. J. , Olson N. F. , Richardson T. 
Published: December 2004

AbstractMilk‐clotting enzymes such as pepsin, chymosin, chymotrypsin, and M. miehei proteases were immobilized on porous, alkylamine glass and incorporated into a fluidized‐bed continuous coagulation scheme. Only pepsin and calf rennet retained sufficient activity towards skim milk to warrant further studies. Comparison of kinetic data with fixed‐bed reactors revealed the overall superior performance of fluidized beds; higher clotting activities were possible while avoiding plugging problems and high pressure drops common to fixed‐bed reactors. Film diffusion and catalyst back‐mixing appear to be significant factors in the overall kinetics.All enzymes lost activity on exposure to skim milk. The inactivation rates were lower at high substrate pH and insignificantly affected by reactor temperature. Nitrogen and sialic acid accumulation on the porous glass paralleled the loss in activity in the initial stages. Attempts to regenerate the immobilized enzymes were partially successful.
Temporal structure of S phase analyzed using an automated synchrony system
Authors: Klevecz Robert R. 
Published: December 2004

AbstractAn automated system for cell cycle analysis is described in which synchronous populations of greater than 95% mitotic cells can be selected and subcultured without resorting to inhibitors or altered media. Selection of mitotic cells from roller bottle cultures generates synchronous populations of up to 5 × 107 cells, as often as every 30 min, under conditions of constant temperature. A detailed analysis of the temporal pattern of DNA synthesis in the S phase of several Chinese hamster cells is presented. Several potential artefacts and uncertainties regarding the cell cycle blockage point in S phase synchronization are discussed.
Primary suspension culture of calf anterior pituitary cells on a microcarrier surface
Authors: Horng Chi‐Byi , McLimans William 
Published: December 2004

AbstractIn order to achieve a steady‐state primary culture system for mammalian cells, with the potential to eventually correlate and control cell function and growth, a serious evaluation of various suspension systems was made. Calf anterior pituitary cells were employed as a differentiated cell type and successfully cultivated in a microcarrier suspension culture system. DEAE‐Sephadex was demonstrated to be a satisfactory type of microcarrier. The cells readily attached to the bead and, after a short lag period, they actively proliferated on the bead surface to yield growth of a predominantly epithelial cell type. Under specific conditions the microcarrier supported primary cell growth up to levels of 2 × 106 cells per ml. High bead concentrations inhibited cell growth. The inhibition could be overcome by using proportionately higher cell inoculum so that a concentrated culture with 5 × 106 cells per ml was achieved. The inhibitory effect of high bead concentration was found to be due to the absorption of serum protein and certain growth enhancing factors. The fact that the growth enhancing factors were released from cells during the period of trypsinization and were both thermostable and nondialyzable, seems to suggest one approach to a dialysis culture system. In addition, relatively trauma‐free primary cell cultures can be achieved by using explant culture without prior trypsinization. In microcarrier suspensions direct growth of primary rat mammary tumor cells was also demonstrated.
Production of the mouse mammary tumor virus in cultures of BALB/cfC3H strain
Authors: Lasfargues Etienne Y. , Lasfargues Jennie C. 
Published: December 2004

AbstractThe mouse mammary tumor virus (MTV) reproduces by a budding mechanism at the cell membrane of mouse mammary epithelial cells. In tissue culture, the tumor cells release their virions in the culture supernatant from which they can be removed by high speed centrifugation. Mammary tumor cells from the RIII, GR, and A strains of mice generally produce yields of virus which decrease after a few months. Cells derived from a spontaneous mammary tumor in a BALB/cfC3H mouse have shown the capability to shed relatively large amounts of virus continuously. A quantitative estimation by membrane immunofluorescence of the number of virus producing cells in one‐year‐old cultures revealed the presence of viral antigen on 80 to 90% of the cells; by comparison, cultures from other mouse strains had a ratio of only 10 to 15% virus producing cells. High speed centrifugation pellets obtained from 50 ml culture supernatant provided large amounts of mature virus particles which have been characterized by electron microscopy.
Growth and immunogenicity of foot‐and‐mouth disease virus in baby hamster kidney cells adapted to and continuously grown in a serum‐free chemically defined media
Authors: Tomei L. D. , Issel C. J. 
Published: December 2004

AbstractThe production of foot‐and‐mouth disease (FMD) virus in baby hamster kidney (BHK) suspension cells grown in serum‐free media for subsequent use in vaccines was attempted because of the limited availability of serum in quantities sufficient for propagation of large amounts of cells, as well as the possible presence of mycoplasma, viral contaminants, and interfering antibodies in sera. Suspension cultures (50 to 600 ml) of BHK‐21 cells adapted to and continually passed in a glutamine‐free autoclavable, chemically defined medium (BHK‐S system) were infected with all seven types of FMD virus. Cells were infected at multiplicities of infection (MOI) ranging from 10−1 to 10−7 plaque‐forming units per cell (PFU/cell). The time course of infectious virus release and the amount of complement‐fixing (CF) antigen produced were then followed. Peak harvest infectivities of approximately 108.5 PFU/ml were obtained from 12 to 24 hr after inoculation, depending on input MOI, and were apparently independent of cell concentration over the range 1.5 to 4.0 million cells/ml; the CF endpoint dilutions increased from 1:12 at the lower cell concentrations to 1:48 at the highest cell concentration. Monovalent and trivalent vaccines have been produced using viruses from the BHK‐S system, inactivated with acetylethyleneimine and emulsified in oil, and the results of tests in steers and guinea pigs are presented.
Effects of growth conditions on the oxygen equivalence of microbial cells
Authors: Grady C. P. L. , Findley P. L. , Muck R. E. 
Published: December 2004

AbstractA natural microbial population of sewage origin was grown at four temperatures (10, 20, 30, 40°C) and five mean residence times (3, 6, 12, 18, 24 hr) in a continuous stirred tank reactor. Samples of cells were removed during steady‐state operation and analyzed for chemical oxygen demand (COD), ash content, protein, carbohydrate, and nucleic acids. The oxygen equivalence (OE) of the cells was measured directly as g COD/g ash‐free cells and was determined indirectly by calculating the calorific content from the macromolecular composition. The results indicate that OE is a function of growth conditions. Furthermore the COD test is a poor measureof OE because of a high level of variation associated with the test. Additional studies should be performed using bomb calorimetry to establish a quantitative relationship between growth conditions and OE.
An automatic homocontinuous culture apparatus
Authors: Ferrara Romano , Grassi Sergio , Del Carratore Giovanni 
Published: December 2004

AbstractAn apparatus for the cultivation of microorganism under controlled conditions is described. This apparatus is basically a turbidostat improved with automatic devices for sample withdrawal and tube cleaning. The results of experiments, using Euglena gracilis to check the constancy of some physiological parameters (in particular phototactic reactivity), are reported.
Effect of carbon dioxide on the formation of α‐amylase by Bacillus subtilis growing in continuous and batch cultures
Authors: Gandhi A. P. , Kjaergaard L. 
Published: December 2004

AbstractThe influence of CO2 on the formation of α‐amylase by Bacillus subtilis NCIB 8646 growing in continuous and batch cultures was investigated.Different levels of CO2 examined in the batch cultures stimulated the formation of α‐amylase, with the highest activity being obtained using 6% CO2(V/V). The additions of CO2 inhibit the growth and division ofvegetative cells of B.subtilis when CO2 is present in a concentration of more than 3%(V/V).In chemostat cultures, air containing 8% CO2 (V/V) increased the specific enzyme productivity almost three times over the control, without affecting the cell growth.An attempt is made to correlate the obtained results withthe already established theory for the regulation of the α‐amylase synthesis.
Kinetic Behavior of Microencapsulated β‐Galactosidase
Authors: Wadiak D. T. , Carbonell R. G. 
Published: December 2004

AbstractEscherichia coli β‐D‐galactosidase (E.C. 3.2.1.23) was immobilized in cellulose nitrate membrane microcapsules and the reaction kinetics with o‐nitrophenyl‐β‐D‐galactopyranoside (ONPG), lactose, and whole milk were studied using both continuous stirred tank and packed bedreactor configurations. The results of the experiments gave effectiveness factors of 0.3 for ONPG, 0.6 to 0.7 for lactose in solution, andclose to unity for lactose in milk. Using a coupled mass transfer and kinetic model, it was possible to estimate the permeability of the microcapsule membrane from the reactor data. Membrane permeabilities on the order of 5 × 10−3 and 3 × 10−4 cm/sec were estimated for ONPG and lactose, respectively. It was determined that the membrane was the limiting mass transfer resistance for the overallreaction. The analysis showed that within the microcapsule, the reaction is reaction rate limited for lactose and slightly diffusion limitedfor ONPG.
Submerged cultivation of a thermotolerant basidiomycete on cereal flours and other substrates
Authors: Hofsten Bengt V. , Rydéean Anna‐Lisa 
Published: December 2004

AbstractThe imperfect state, Sporotrichum pulverulentum, of thecellulolytic basidiomycete Phanerochaete chrysosporiumhas been grown on barley flour and other agricultural products in shake cultures, in an air‐lift fermentor, and in stirred fermentors. The growth morphology varied with cultivation conditions, but it was possible to maintain heavy suspensions of loosely associated mycelia in fermentors. The fungus can grow in temperatures up to 40°C and use ammonium salts or organic nitrogen sources to convert sugars, starch, pectin, and various seed residues to a biomass containing 30–40% protein with a favorable amino acid composition. Serial cultures were grown on flours under conditions where the larger part of the culture was withdrawn and replaced with new medium every, or every other, day. The mycelia are easy to harvest by filtration and have several properties which make the product attractive as a potential food ingredient.
Cellulase and protein production from mixed cultures of Trichoderma viride and a yeast
Authors: Peitersen Nicolai 
Published: December 2004

AbstractFermentations with mixed cultures of the cellulolytic fungus Trichoderma viride and the yeast Saccharomyces cerevisiae or Candida utiliswere examined. The fermentations were carried out in an aerated 5 liter fermentor with NaOH treated barley straw as the cellulose source (2–4%). Yeast was inoculated 24–32 hr after the fungus and the growth of the two organisms was followed through the production of CO2 and cell protein. In comparison with fermentations with T. viridealone, the production time for maximum yields of cellulases and cell protein was reduced by several days, depending on the straw concentrations. The protein content of the growth product was 21–22% and the amino acid composition of the product resembled that of T. viride alone.
The total containment of a batch‐type zonal centrifuge
Authors: Webb N. L. , Richards B. M. , Gooders A. P. 
Published: December 2004

AbstractA batch‐type zonal centrifuge has been modified and totally contained for use with biologically hazardous materials.A sealed cabinet encloses the centrifuge and the ancilliary equipment. It is operated with a flow of filtered air when the zonal system is on, decontaminated with ethylene oxide, and maintained at a negative pressure throughout. The centrifuge subsystems can be drained, flushed, and decontaminated with ethylene oxide before an engineer services the machine. The sample handling system within the cabinet is remotely controlled.
Studies on the production of bacterial rennet in a pilot plant fermentor
Authors: Rao Lavu Krishna , Mathur D. K. 
Published: December 2004

AbstractAn attempt was made to find out the optimum aeration and agitation rates on the production of bacterial rennet from Bacillus sublilis K‐26 using 5% wheat bran medium in a 13 liter fermentor. The enzyme activity and the growth rate were shown to increase with an increase in the rate of agitation. The fermentation experiments carried out at an agitation rate of 400 rpm showed an approximate threefold increase in enzyme activity with a considerable decrease in the fermentation time over those agitated at 200 and 300 rpm. The beneficial effect of a higher oxygen rate was observed for enzyme production occurring at a lower agitation rate. The inoculum activity and the varying amounts of antifoam agent which were added showed no apparent effect either on the total incubation time or on the final enzyme activity. It has been suggested that an agitation rate of 400 rpm with an aeration level of 3000 cc/min are the optimum values for the efficient production of bacterial rennet from B. subtilis K‐26 using 5% wheat bran medium in a 13 liter fermentor.
Kinetic studies on insoluble cellulose–cellulase system
Authors: Huang Andrew A. 
Published: December 2004

AbstractEnzymatic hydrolysis of insoluble amorphous cellulose by Trichoderma viride cellulase was investigated in a batch reactor at several substrate concentrations and three enzyme levels. The reactions were carried out at 50°C and pH 4.8. Enzyme was rapidly adsorbed onto solids on contact, then gradually returned to the liquid phase as the reaction proceeded. A kinetic model that considered the fast adsorption which was followed by the slow reaction, and subsequent product inhibition was developed to interpret the experimental observations. The resulting equation successfully correlated the data for up to 70% conversion. The methods for determining the kinetic parameters are discussed.
Preparation and kinetic properties of gel entrapped urate oxidase
Authors: Hinberg I. , O'Driscoll K. F. 
Published: December 2004

AbstractUrate oxidase from hog liver (urate: oxygen oxidoreductase, EC 1.7.33) has been entrapped in a crosslinked 2‐hydroxyethyl methacrylate gel with a 47% retention of activity. The kinetic behavior of the gel entrapped enzyme has been studied in a slurried tank reactor using uric acid as substrate. Internal diffusion effects were found to be negligible for particle sizes below 128 μm. A threefold increase in Km (app) was observed for the 128 μm particles and attributed to diffusional effects. The pH activity profile of the gel entrapped enzyme was bell‐shaped at high substrate concentration and could be fitted to a titration curve of two ionizable groups, a basic group having a pK of 7.9 and an acidic group with a pK of 11.0. The gel entrapped enzyme showed excellent stability between pH 6.5 and 10.5.
New suspension culture system (Mini‐AR)
Authors: Dynesius Roselynn , Lange Robert D. , Eraslan Arsev H. , Snyder William T. 
Published: December 2004

AbstractA new suspension culture system (Mini‐AR) based on the Stoke's drag law for suspended particles is described. This apparatus can be utilized for the maintenance of mammalian kidney cells in both short‐ and long‐term cultures.
The response of a bioelectrochemical cell with Saccharomyces cerevisiae metabolizing glucose under various fermentation conditions
Authors: Videla H. A. , Arvía A. J. 
Published: December 2004

AbstractWorking conditions of a biochemical fuel cell formed by an oxygen cathode and a platinum bioanode in a Saccharomyces cerevisiae suspension metabolizing glucose are described. The biocell response in terms of bioanode potential and current drainage under different fermentation conditions is reported. A kinetic equation relating the current, the number of microorganisms, and the substrate concentration is obtained. The bioanode potential corresponds to that of an oxygen concentration polarization cell.
On‐line measurement of gas‐exchange conditions in fermentation processes
Authors: Nyiri Laszlo K. , Toth Gizella M. , Charles Marvin 
Published: December 2004

AbstractGas‐exchange conditions of C. ulilis cultures were analyzed by an on‐line, real‐time operating digital computer interfaced with a 250 liter, highly instrumented fermentor.Information obtained from the computer was correlated with wet chemical analytical data related to nucleic acid, protein, and ethyl alcohol production rates. Once the correlation was established, the computed gas‐exchange data, especially the RQ which functions as an indicator of the cells physiological condition, could be used as a real‐time process status indicator which follows or forecasts events during the fermentation.It was also found that electrical noises generted on the sensor‐instrument level may handicap the interpretation of the meaning of computed process status indicators. Since “clear” data is considered as a prerequisite to follow the physiological conditions and perform control of environmental variables, a special computer program is necessary to filter the electric noises at the sensor‐instrument level prior to the on‐line, real‐time data analysis for process status identification.
Interparticle mass transfer study with a packed column of immobilized microbes
Authors: Toda K. 
Published: December 2004

AbstractThe kinetics of whole‐cell lactase of Escherichia coli immobilized in spherical agar gels was determined under the influence of interparticle mass transfer in a fixed bed reactor. The dependence of the pseudokinetic parameters (K′m and v′max) fluid conditions was in accordance with the prediction derived from combinedeffects of kinetics and mass transfer. Within the limited conditions of theexperiments, it was observed that the apparent Michaelis constant could be represented by the following simple equation, K′m/Km = 1 + (ϕ/kLa)(vmax/Km).The mass transfer coeflicient (kL) needed in the theoretical analysis was determined in correlation with particle size (0.12–0.45 cm) and liquid flow rate (0.30–12.0 cm/min) using the more stable enzyme, cell‐bound invertase of Saccharomyces pastorianus, as the material to be entrapped in the gelatinous particles. The relationship was expressed in the following dimensionless equation, (1–ϕ)Sh = 2 + 0.6Re1/2Sc1/3, except that marked deviation resulting in the reduction of kL was noticed with a Reynolds number less than 0.8.
Effectiveness factors for substrate and product inhibition
Authors: Wadiak D. T. , Carbonell R. G. 
Published: December 2004

AbstractThe transformation technique of Na and Na (Math. Biosci., 6, 25, 1970) is extended to convert boundary‐value problems involving the steady‐state diffusion equation for spherical immobilized enzyme particles exhibiting substrate and product inhibition to initial‐value problems. This allows a study of the influence of external mass transfer resistances on the effectiveness factors. It also considerably reduces the number of calculations required to investigate the effect of changes in the kinetic parameters on the overall rate of reaction. The existence of multiple steady states for substrate inhibition kinetics in spherical catalyst particles is illustrated and a criterion for uniqueness of steady states is developed. Effectiveness factors for competitive and noncompetitive product inhibition increase with increasing value of the Sherwood number for the substrate and increasing value of the ratio of substrate to product effective diffusivities within the particle.