bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the inherent deactivation characteristics for the parallel poisoning of immobilized catalase
Authors: Tai Nguyen M. , Greenfield P. F. 
Published: December 2004

AbstractAn approximate analytical solution which describes the deactivation of catalase immobilized on porous supports is provided. Catalase was chosen as an example of an enzyme which undergoes parallel poisoning. The solution incorporates the effects of pore diffusion and of the parallel poisoning. The solution incorporates the effects of pore diffusion and of the parallel poisoning of catalase by its substrate hydrogen peroxide into a time dependent effectiveness factor which can then be inserted into the appropriate reactor equations. The model was tested by measuring experimentally the deactivation of immobilized catalase in both a packed bed reactor and a continuous stirred basket reactor and was found to be very satisfactory at inlet substrate concentrations of less than 0.02M. Values of the deactivation rate constant obtained by regression analysis were independent of particle type and size and reactor description indicating that they were in fact inherent characteristics of the immobilized enzymes which are immobilized on supports and which undergo substrate or parallel poisoning.
Immobilization of the methanogenic bacterium Methanosarcina barkeri
Authors: Scherer P. , Kluge M. , Klein J. , Sahm H. 
Published: December 2004

AbstractWhole cells of the methanogen Methanosarcina barkeri were immobilized in an alginate network which was crosslinked with Ca2+ ions. The rates of methanol conversion to methane of entrapped cells were found to be in the same range as the corresponding rates of free cells. Furthermore, immobilized cells were active for a longer period than free cells. The particle size of the spherical alginate beads (1.2 mm‐3.7 mm ϕ) and thus diffusion had no obvious influence on the turnover of methanol. The half‐value period for methanol conversion activity determined in a buffer medium was approximately 4 days at 37°C for entrapped cells. The apparent Km value K for such cells was nearly 140mM and the Vmax value was about 1.2 μmol methanol/min/mg entrapped protein. Therefore the high rates of methanol degradation measured, e.g., 0.5 μmol methanol/min/mg entrapped protein, indicated that the immobilization technique preserved the cellular functions of this methanogenic bacterium.
Lactate and ethanol as intermediates in two‐phase anaerobic digestion
Authors: Pipyn P. , Verstraete W. 
Published: December 2004

AbstractThe thermodynamics of the various anaerobic digestion patterns of hexose to methane are compared. It appears that by directing the hexose‐hydrolysis phase towards ethanol and lactic acid production, methanogenesis can be enhanced because the syntrophic bacteria are allocated more potentially available energy. This hypothesis was confirmed in a series of laboratory test runs. They revealed that lactic acid and ethanol as intermediates, in comparison to lower volatile fatty acids, give rise to a considerably higher effluent quality and a slightly larger biogas production.
A two‐phase oxygen uptake model of aerobic fermentations
Authors: Sobotka M. , Votruba J. , Prokop A. 
Published: December 2004

AbstractThe mechanism of Solid particle flotation was used for explaining an alternative route of oxygen uptake by cells situated within the relatively stagnant liquid region adjacent to bubbles in a submerged culture. The Two‐phase model of oxygen uptake takes into consideration uptake from both liquid and gaseous phases, the latter being denoted as the direct uptake. Experiments obtained with yeast cultures on different substrates were used to evaluate the proportion of both types of uptake. The combined model provides a better fit to experimental data compared to the one‐phase model which omits the direct uptake. The results are discussed from the viewpoint of the enhancement of oxygen absorption by cells present near the interface.
Technological problems in cultivation of plant cells at high density
Authors: Tanaka Hideo 
Published: December 2004

AbstractUsing Cudrania tricuspidata cells as model plant cells which have high sensitivity to hydrodynamic stress, technology problems in the cultivation of the plant cells at high density were investigated. Using “shake” flasks on a reciprocal shaker and Erlenmeyer flasks on a rotary shaker and with a high supply of oxygen on order to obtain high cell densities in shaken cultures, particles breakdown and damage to the largest cell aggregate group (above 1981 μm in diameter) occurred and normal cell growth became impeded. The mass‐transfer coefficient (K)for a model solid–liquid system (β‐naphthol particles and water) in place of a system of plant cells and a liquid medium was proposed as an intensity index of hydrodynamic stress effects on plant cells in subsequent cultures under various conditions in the bioreactor systems. Normal cell growth was obtained under culture conditions for K values less than about 4.4 × 10−3 cm/sec. The characteristics of various bioreactors used until now were investigated by considering the three main technological factors (capacity of oxygen supply, intensity of hydrodynamic stress effects on plant cells, and intensity of culture broth mixing and air‐bubble desperation). The most suitable bioreactor for culturing plant cells at high density was ajar fermentor with a modified paddle‐type impeller (J‐M). The yield of cell mass in the 10‐liter J‐M (working volume 5 liter) was about 30 g dry weight per liter of medium.
Process development and evaluation for algal glycerol production
Authors: Chen Bill J. , Chi C. H. 
Published: December 2004

AbstractThis article and develops a process for large‐scale production of glycerol by means of a hemophilic algae. The process is shown to be economically and technically feasible. Although the proposed process is extremely capital intensive, the total production cost is competitive with existing glycerol process. In addition, the overall energy requirement is much lower than that of the petrochemical process. This proposed process provides an alternative route for glycerol production that is minimally dependent on fossil fuels and is therefore, less sensitive to crude oil availability and price. The primary raw material carbon dioxide from stack gas, is an inexpensive and renewable resource. Maximal Utilization of solar energy is made not only in the glycerol synthesis steps but also in the product recovery system. Significant improvement in the process economics can be realized through further development of large‐scale cultivation technology, and biomass distribution and collection machinery. Due to the labor intensive nature of the proposed algal process, it is particularly suitable for less developed nations with limited fossil fuel resources and lower labor costs.
Growth of cellulolytic bacteria on sugarcane bagasse
Authors: Enríquez A. 
Published: December 2004

AbstractThe growth behavior of Cellulomonas has been examined in fermentation system using alkali pretreated sugarcane bagasse. During the batch operation diauxic growth was found which would not seem to be explained by catabolic repression. The relative variation of cellulose and hemicellulose during the fermentation process suggests the initial utilization of easily degradable substrate, i.e., hemicellulose and amorphous cellulose, until their concentration becomes limiting, followed by utilization of the crystalline cellulose. The conversion of substrate was 70% with a yield of 0.355 g of biomass per gram of bagasse feed.
Kinetics of the isomerization of D‐glucose into D‐fructose catalyzed by glucose isomerase containing Arthrobacter cells in immobilized and nonimmobilized form
Authors: Van Keulen M. A. , Vellenga K. , Joosten G. E. H. 
Published: December 2004

AbstractThe kinetic properties of immobilized and nonimmobilized glucose isomerase have been investigated. In both cases the kinetics can be described by a modified Michaelis–Menten expression. It appeared that immobilization causes no deactivation. Furthermore, it was shown that the permeability of the cell membrane increases by heat and toluene treatments.
Automatic control for fed‐batch culture of single cell protein
Authors: Huang Shih Yow , Chu Wey‐Bang 
Published: December 2004

AbstractCandida utilis was cultivated in a 5‐liter jar fermentor using ethanol as sole carbon source. Control of ethanol in the cultivation broth was performed by using an ethanol vapor monitoring instrument and an oxygen electrode coupled with two control circuits. By setting upper and lower bounds according to the predetermined conditions, a signal from a gas monitoring sensor switched the lower or higher bound relay governing the actuating or switch‐off of the motor; this maintained a proper concentration of ethanol in the cultivation of ethanol in the system. The growth of cells was found to be satisfactory. Cell concentration reached 64 g/liter during a 20‐hr cultivation. As the results of comparative experiments, the control mode using the gas monitoring instrument was found to be superior to that using dissolved oxygen as a controlling signal, especially at high cell concentration.
Application of immobilized aminoacylase from Micrococcus agilis for isolation of D‐phenylglycine from its racemic mixture
Authors: Szwajcer E. , Szewczuk A. , Mordarski M. 
Published: December 2004

AbstractThe procedure for isolation of D‐phenylglycine from its racemic mixture by enzymatic hydrolysis of L‐enantiomer of N‐acetyl‐D,L‐phenylglycine is described. For this hydrolysis. aminoacylase from Micrococcus agilis immobilized by sorption of DEAE‐cellulose was applied. As is also shown, the course of enzymatic reaction can be directly controlled by spectrophotometric method.
Simulation of the integration of the internal energy metabolism and cell cycle of Saccharomyces cerevisiae
Authors: Hall R. J. , Barford J. P. 
Published: December 2004

AbstractA computer simulation of the integration of the internal energy metabolism and the cell cycle of Saccharomyces cerevisiae is described. This was attempted, for the first time, as a result of the observation that in this organism the overall or average external metabolic exchange rates often differed considerably from the internal metabolic fluxes which they are normally assumed to represent. This was the result of such factors as the variation in the nature of the metabolism of the organism depending on its stage in the cell cycle and redox interactions between anabolism and catabolism. The overall result of this simulation is the prediction of the internal metabolic fluxes consistent with the experimentally determined external fluxes. While these simulation depend on the assumption regarding the energetics and cell cycle of Saccharomyces cerevisiae, they provide a means of examining with precision such processes as the energetics of cell growth and cell cycle variation. As a result, within these limitation, they allow the systematic study of coordinated cell control. Such an approach provides a useful and largely unused adjunct to the experimental approaches which have attempted the study of coordinated metabolic regulation.
Design of a nonuniformly distributed biocatalyst
Authors: Park Sun Ho , Lee Sun Bok , Ryu Dewey D. Y. 
Published: December 2004

AbstractThe properties of a nonuniformly distributed biocatalyst, where the active enzymes are immobilized on the exterior or the interior portions o a solid support, are compared with those of a conventional biocatalyst which is uniformly distributed in a spherical geometry. To investigate the performance of nonuniformly distributed biocatalysts their effectiveness factors are computed and compared for six different enzyme distribution configurations: one‐half core, one‐half shell, one‐third center space, one‐third middle annulus, one‐third outer shell, and the uniformly distributed. According to the results of numerical analysis, the biocatalyst performance of the exterior "shell" configuration is always far more effective for the immobilized enzymes with positive order reaction kinetics such as Michaelis‐Menten and competitive product inhibition. However, in the case of negative order enzymatic reaction kinetics such as substrate inhibition, the interior "core" configuration of the biocatalyst can render far greater enzyme utilization efficiency.
Mechanical control of the activity of glucose oxidase immobilized on porous polyvinylchloride membrane
Authors: Ishimori Yoshio , Karube Isao , Suzuki Shuichi 
Published: December 2004

AbstractGlucose Oxidase was immobilized on a porous polyvinylchloride (PVC) membrane. The activity of the glucose oxidase‐PVC membrane decreased when the membrane was mechanically stretch. A linear relationship was observed between the stress and the relative logarithmic activity of the glucose oxidase‐PVC membrane. Apparent Michaelis constant (Km′) and maximum velocity (Vm′) of the glucose oxidase‐PVC membrane under stretched conditions were 1.4 and 0.71 times those without stretching, respectively. The decrease of the membrane activity with stress was reproducible. Therefore, the glucose oxidase activity of the membrane can be controlled with stress.
Design and performance of a new microcalorimetric system for aerobic cultivation of microorganisms
Authors: Ishikawa Yasufumi , Shoda Makoto , Maruyama Hiromu 
Published: December 2004

AbstractA twin‐type heat‐conduction calorimeter for an aerobic fermentation process was designed and constructed fermentor both in batch and continuous runs. The time constant of the calorimeter was 3.3 min. The volumetric oxygen transfer coefficient (kLa) of the vessel was measured by a sulfite oxidation method in a continuous flow system under various rotation speeds and gas flow rates. Sufficient thermal stability of the calorimeter was obtained both in batch and continuous runs within the operation time period.
Mutagenesis and carcinogenesis testing in vitro
Authors: Casto Bruce C. 
Published: December 2004

AbstractThe development and validation of short‐term tests for carcinogens and mutagens are urgently needed if estimates of 70–80% for environmentally induced cancer are valid. Several methods for in vitro testing have been described in microbial and mammalian cells. It is anticipated that a battery of tests will soon be available with high degree of reproducibility and predictability for potential in vivo carcinogenesis. This review discusses those assays currently being implemented in mammalian cells including a brief description of the methodology, advantages, and disadvantages, and the correlation with known in vivo activity.
Microcarrier culture: Applications in biological production and cell biology
Authors: Crespi Charles L. , Imamura Toshiko , Leong Phaik‐Mooi , Fleischaker Robert J. , Brunengraber Henri , Thilly William G. , Giard Donald J. 
Published: December 2004

AbstractThis report reviews recent progress in micro carrier technology at the Massachusetts Institute of Technology. This progress includes new understanding of the nutritional needs of high‐cell density micro carrier cultures, the demonstration of cell growth on microcarriers in a hormone‐supplemented, serum‐free medium, and the continuous cell propagation of epithelial cell types in microcarrier culture by medium modification that permits efficient bead‐to bead transfer. Also, a technique for obtaining large quantities of mitotic cells by selective detachment from microcarriers is reported. Finally, recent progress in interferon production from human foreskin fibroblasts grown on microcarriers is outlined: Our improvements in the interferon “super induction” process have increased the interferon yield per cell fivefold to tenfold.
Phenotypic variation in plants regenerated from protoplasts: The potato system
Authors: Bidney Dennis L. , Shepard James F. 
Published: December 2004

AbstractRegeneration of whole plants from isolated protoplasts (plant cells devoid of cell walls) provides a novel capability that is potentially useful for crop improvement efforts. Such a regeneration capacity has been developed for the commercial potato cultivar ‘russet Burbank,’ currently the most popular cultivar in production. Due to fertility problems of this cultivar, the improvement of ‘russet Burbank’ by classical breeding procedures has been limited. Examination of a large population of protoplast‐derived clones has revealed the variation for a number of traits can be observed. Variation observed under laboratory conditions and in field trials includes changes in plant morphology and tuber‐setting characteristics, as well as alterations in response to environmental and pathogen stress. A brief description of the cloning process and the potential for application of cloning technology in crop plant improvement will be presented.
Prediction of the degradability of sugarcane celulosic residues by indirect methods
Authors: Cabello Agustín , Conde José , Otero Miguel A. 
Published: December 2004

AbstractThe effect of mild NaOH treatments on sugarcane cellulosic wastes (bagasse, pith, and straw) to increase their biological degradability has been studied. At a level of 8% NaOH (on a dry matter basic) 60% digestibility measured by the in vitro technique was achieved for all materials tested. Indirect methods to predict the digestibility of treated materials such as the bacterial degradability, enzymatic degradability, hot‐water solubility, and chemical oxygen demand were tried as alternative methods to the rumen fluid technique. High correlation coefficients for all materials were obtained with all alternative techniques. The minimal r value was 0.96 while the highest was 0.99. An important reduction of time and reagents is achieved by the utilization of the solubility and chemical oxygen demand tests.
Immobilization of microbial cells in crosslinked, prepolymerized, linear polyacrylamide gels: Antibiotic production by immobilized Streptomyces clavuligerus cells
Authors: Freeman A. , Aharonowitz Y. 
Published: December 2004

AbstractA mild new method for the immobilization whole microbial cells has been developed. Cells were suspended in a solution of preformed, linear, water‐soluble Polyacrylamide chains, partially substituted with acylhydrazide groups. The Prepolymerized backbone polymer was crosslinked, in the presence of viable cells, by stoichiometric amounts of dialdehydes such as glyoxal, glutardialdehyde, and period ate‐oxidized polyvinyl alcohol. The crosslinking reaction, carried out in cold, neutral physiological conditions resulted in cells entrapped in gels with physical properties similar to those of the common Polyacrylamide gels. However, cell damage generally caused by the acrylamide monomer was avoided. Resting Streptomyces clavuligerus cells, possessing a high capacity for antibiotic production, were entrapped according to this procedure. These immobilized cells produced cephalosporins continuously for 96 h with yields similar to those of free resting cells. The same cells, when immobilized by direct polymerization acrylamide monomers, yielded significantly lower amount of antibiotics.
A model for noninhibitory microbial growth
Authors: Chiam H. F. , Harris I. J. 
Published: December 2004

AbstractA model for noninhibitory microbial growth has been developed which is superior to the Monod model in that it can predict the decline in steady‐state growth yields at both the slow and the fast specific growth rates. The model parameters are evaluated from data obtained for steady‐state, phenol‐limited Pseudomonas putida growth using a conventional 1‐dm3 cheniostat. The model also has been successfully applied to Mor and Fiechter's data for cheniostat yeast cultures.
Unstructured model for growth of mycelial pellets in submerged cultures
Authors: Van Suijdam J. C. , Hols H. , Kossen N. W. F. 
Published: December 2004

AbstractAn unstructured model is presented to describe growth of mycelial pellets in submerged cultures. This model integrates growth kinetics at the scale of the hyphae with the physical mechanisms of mass‐transfer processes at the scale of the pellets and the fermentor. The main elements of the model are biomass, substrate, and oxygen balances for the liquid phase and the pellets. The possible occurrence of oxygen limitation in the pellets is introduced in analogy with catalyst theories by means of an effectiveness factor. To simulate the growth of pellets the model is transferred into a computer program. The model is tested by means of fermentation experiments in a bubble column. Results of the growth experiments compare favorably with the outcome of computer simulations.
Enhancement of enzymatic hydrolysis by simultaneous attrition of cellulosic substrates
Authors: Neilson Martin J. , Kelsey Rick G. , Shafizadeh Fred 
Published: December 2004

AbstractIt has been shown that simultaneous attrition of cellulose in an attritor containing stainlesssteel beads results in a substantial enhancement of the enzymatic hydrolysis. The attrition exerts two opposing effects, continuous delamination and comminution of the substrate with formation of new reactive sites and a gradual denaturation and inactivation of the enzyme. Consequently, the hydrolysis proceeds very rapidly at first and levels off at about 70% saccharification of the substrate. Accumulation of hydrolysis products is also responsible for inhibition of the enzyme. The attrition method is effective for the saccharification of cottonwood in which the cellulosic microfibrils are embedded in a matrix of lignin and hemicelluloses. A comparison between the saccharification of wood, lignocellulose, holocellulose, and cellulose with simultaneous attrition showed that the lignin component provided more hindrance toward the saccharification process than hemicelluloses, which are themselves subject to enzymatic hydrolysis.
Kinetics of immobilized sucrose phosphorylase
Authors: Taylor Frank , Chen Lifu , Gong Cheng Shung , Tsao G. T. 
Published: December 2004

AbstractSucrose phosphorylase was immobilized on porous ceramic beads with 3‐aminopropyltriethoxysilane and glutaraldehyde. It was determined experimentally that under laboratory conditions there was no diffusional resistance to the enzyme‐catalyzed reaction. The half‐life of the immobilized enzyme varied from about 35 days at 30°C to about 5 days at 40°C. The pH optimum was found to be between 6.5 and 7.0. The activation energy for the reaction was found to be about 12.5 kcal/mol. Eleven independent kinetic constants in the complete rate equation for the previously proposed ping–pong mechanism were found to be in good agreement with those for the soluble enzyme.
Studies on immobilized Saccharomyces cerevisiae. I. Analysis of continuous rapid ethanol fermentation in immobilized cell reactor
Authors: Tyagi R. D. , Ghose T. K. 
Published: December 2004

AbstractRapid fermentation of cane molasses into ethanol has been studied in batch, continuous (free‐cell and cell‐immobilized systems) by a strain of Saccharomyces cerevisiae at temperature 30°C and pH 5.0. The maximum productivity of ethanol obtained in immobilized system was 28.6 g L−1 h−1. The cells were immobilized by natural mode on a carrier of natural origin and retention of 0.132 g cells/g carrier was achieved. The immobilized‐cell column was operated continuously at steady state over a period of 35 days. Based on the parameter data monitored from the system, mathematical analysis has been made and rate equations proposed, and the values of specific productivity of ethanol and specific growth rate for immobilized cells computed. It has been established that immobilized cells exhibit higher specific rate of ethanol formation compared to free cells but the specific growth rate appears to be comparatively low. The yield of ethanol in the immobilized‐cell system is also higher than in the free‐cell system.