bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bed expansion characteristics of liquid fluidized particles with attached microbial growth
Authors: Ngian Kian‐Fah , Martin William R. B. 
Published: December 2004

AbstractThe bed expansion behavior of liquid fluidized beds of char particles coated with attached microbial growth of denitrifying mixed bacteria was studied experimentally to obtain an expression that relates the bed expansion to the liquid velocity for liquid fluidized beds of composite particles. As for liquid beds of homogeneous spheres, the bed voidage and the liquid velocity vz for liquid fluidized beds of biomass‐coated particles were found to be related as vz/Vi = ∈n. The correlations recommended by Richardson and Zaki for homogeneous spheres are found to be satisfactory for the estimation of the constant n, but only under certain conditions for the constant Vi.
Oxygen supply to bacterial suspensions of high cell densities by hydrogen peroxide
Authors: Ibrahim M. , Schlegel H. G. 
Published: December 2004

AbstractThe supply of heterotrophically growing suspensions of Alcaligenes eutrophus PHB−4 with oxygen formed by the continuous addition of H2O2 in the presence of bovine liver catalase was found to be restricted to well‐defined conditions. The catalase‐H2O2 system proved to be suitable during the growth at low cell densities equivalent to 2 g dry weight/liter. When under these conditions the oxygen concentration was held constant at 1.8 mg O2/liter, the cells grew for 6–8 hr at a rate almost identical to that observed with conventional aeration. However, aeration with H2O2 for longer durations (10–20 hr) and at higher cell densities (5−20 g dry weight/liter) led invariably to cell damage and retardation of growth. The impairment of growth observed during the oxygen supply by the catalase−H2O2 system was traced back to the formation of gradually increasing steady‐state concentrations of H2O2 in the medium. Possible sites of cell damage by H2O2 such as membrane function, excretion and function of siderophores, and synthesis of cell polymers have been studied, and the cytotoxic mechanism of low concentrations of H2O2 was discussed.
Continuous conversion of sucrose to fructose and gluconic acid by immobilized yeast cell multienzyme complex
Authors: D'Souza S. F. , Nadkarni G. B. 
Published: December 2004

AbstractA multienzyme complex consisting of invertase, glucose oxidase, and catalase was reconstituted by binding glucose oxidase using concanavalin A (Con A) to the cell wall of Sacchararomyces cerevisiae, previously induced for maximal activities of invertase and catalase. The cell flocculate obtained was stabilized by entrapment in polyacrylamide using γ irradiation at 100 kR. This complex showed a shortening of the lag period and enhancement in gluconic acid production as compared to a similar mixture of soluble enzymes. The efficacy of the multienzyme complex has been compared with that of mixed multienzyme system composed of individually immobilized enzymes. The immobilized multienzyme complex in a continuous‐flow stirred‐tank reactor system could be operated for continuous conversion of sucrose to fructose and gluconic acid. The reactor system did not show any loss in efficiency in a continuous operation over 20 days.
Nutritional evaluation of the white‐rot fungus Sporotrichum pulverulentum as a feedstuff to rats, pigs, and sheep
Authors: Thomke S. , Rundgren M. , Eriksson S. 
Published: December 2004

AbstractThe production of single‐cell protein (SCP) based on cheap carbon sources such as spent liquor from paper mills is of interest for different reasons. The White‐rot fungus (Sporotrichum pulverulentum) has earlier been shown to degrade cellulose and lignin. The nutritive value of this fungus was investigated with rats, pigs, and sheep. The effect of different drying process was evaluated on rats. Experiments with piglets, growing pigs, and sheep were aimed at getting primary information on nutritive parameters with domestic animal species, Chemical analysis of S. pulverulentum showed that the sum of the amino acids corresponded to 70% and ammonia, GABA, and glucosamine to 20% of its crude protein content. Differences between drying treatments in their effect on protein digestibility were not noted. From a protein quality viewpoint, a tendency toward superiority was noted for two of the drying processes. The amino acid digestibility of S. pulverulentum was inferior to values for soybean oil meal given in textbooks. The piglet experiment confirmed the lower nutritive value of S. pulverulentum compared with soybean oil meal. in the piglet stage a content of metabolizable energy of S. pulverulentum was found which corresponded to 60% of that for soybean oil meal. With increasing age the ability of pigs to utilize the fungus increased. The limited nutritive value for monogastric animals is most certainly caused by the cell‐wall structure of S. pulverulentum with poor digestibility of the carbohydrates. The experiment with sheep showed more satisfactory results than with monogastric species, with digestibility of crude protein of 82% and a content of metabolizable energy of 70% of soybean oil meal.
Morphological and ultrastructural study of the cell envelope of thermophilic and acidophilic microorganisms as compared to Thiobacillus ferrooxidans
Authors: Berry V. K. , Murr L. E. 
Published: December 2004

AbstractThe cell envelope of a Sulfolobus‐like microorganism has an arrayed hexagonal subunit structure, a double‐layered cytoplasmic membrane, and a hollow periplasmic space between the plasma membrane and the outermost arrayed layer. A dense peptidoglycan layer outside the plasma membrane found in the case of Thiobacillus ferrooxidans was not seen. The cell envelope of a thermophile isolated from a leaching environment has a well‐defined envelope with two well‐stained layers distinclty seen. While the peptidoglycan layer is also not seen in this thermophile, a long flagellum similar to that in the case of T. ferrooxidans is present. The presence of pili in the Sulfolobus‐like organism and its arrayed subunit cell envelope structure could account for the organism's selective attachment to sulfide phases in the leaching of low‐grade ores. The observations of a well‐defined cell envelope in the two thermophiles is consistent with the structure‐function relationship previously established for T. ferrooxidans.
Relationship between phosphate stress, effluent quality, and observed cell yield in a pure‐oxygen activated‐sludge plant
Authors: Verstraete W. , Vissers W. 
Published: December 2004

AbstractThe effect of continuous and discontinuous phosphate stress on the observed cell yield coefficient was investigated in a petrochemical pure‐oxygen wastewater treatment plant. A continuous phosphate stress in the activated‐sludge system resulted in a reduction of sludge production by 36%, but no improvement of the effluent quality was noticed compared with that of nonstress treatment. However, discontinuous phosphate stress produced a high‐quality effluent due to the excellent setting settling properties of the sludge flocs. In addition, the observed cell yield coefficient and concomitantly the sludge production remained 45% below normal. The introduction of the discontinuous phosphate stress in the pure‐oxygen activated‐sludge plant at the BP Chemicals works in Antwerp resulted in a 24% reduction of the total wastewater treatment operating costs.
Microrecirculation reactor system for characterization of immobilized enzymes
Authors: Taylor James B. , Swaisgood Harold E. 
Published: December 2004

AbstractA differential microrecirculation reactor was developed for kinetic analysis of both soluble and immobilized enzymes. The reactor system was easliy fabricated with in the laboratory from readily available materials. The disposable, small reactors allowed for in situ weight determination of the enzyme beads. Routinely, only a 1 ml liquid volume of substrate was used for each kinetic assay. The reactor system was also used for determination of partition coefficients. Both uses of the reactor system required only 5–10 min for completion of a given determination.
Total containment of a continuous‐flow zonal centrifuge
Authors: Gooders A. P. , Webb N. L. , Allen G. J. , Richards B. M. 
Published: December 2004

AbstractA continuous‐flow, high throughput, turbine‐driven zonal centrifuge has been contained for use with biologically hazardous materials. The centrifuge and all ancillary equipment are enclosed in three sealed cabinets that are maintained at negative pressure, decontaminated with ethylene oxide, and provide cooling for the process fluids. Sample handling is semiautomated and remotely controlled for ease of operation and includes an automated decontamination system. The centrifuge subsystems can be decontaminated prior to an engineer servicing the machine, and apparatus is provided for absolute filtration of the centrifuge turbine exhaust.
Influence of engineering variables upon the morphology of filamentous molds
Authors: van Suijdam J. C. , Metz B. 
Published: December 2004

AbstractA modal has been described for the influence of growth rate and shear stresses in the fermentor upon the morphology of filamentous molds. The main concept of this model is the dynamic equilibrium between growth and breakup of the hyphae. The latter has been approached according to well‐known engineering theories for dispersion of physical systems. Experiments to verify the model with a strain of Penicillium chrysogenum in batch and continuous culture revealed that the length of the mycelial particles increased with increasing growth rate and decreased with increasing power input her unit mass in the fermentor. Although this was qualitatively in agreement with the presented model, quantitatively the model had to be rejected. Variation of the tensile strength of the hyphae with age and culturing conditions could have been one of the causes of disagreement. Oxygen tension, varied independently from stirrer speed, in the range of 12–300 mm Hg was shown to have no influence upon the morphology. With respect to the question of possibly using high‐energy inputs in industrial mold fermentation in order to decrease hyphal length and suspension viscosity, it was concluded that this is of little practical value. A substantial decrease in hyphal length requires an enormous increase in energy input.
Raw materials evaluation and process development studies for conversion of biomass to sugars and ethanol
Authors: Wilke C. R. , Yang R. D. , Sciamanna A. F. , Freitas R. P. 
Published: December 2004

AbstractA range of cellulosic raw materials in the form of agricultural crop residue was analyzed for chemical composition and assessed for potential yields of sugars through chemical pretreatment and enzymatic hydrolysis of these materials. Corn stover was used as a representative raw material for a preliminary process design and economic assessment of the production of sugars and ethanol. With the process as presently developed, 24 gal ethanol can be obtained per ton of corn stover at a processing cost of about $1.80/gal exclusive of by‐product credits. The analysis shows the cost of ethanol to be highly dependent upon: (1) the cost of the biomass, (2) the extent of conversion to glucose, (3) enzyme recovery and production cost, and (4) potential utilization of xylose. Significant cost reduction appears possible through further research in these directions.
Characterization of anaerobic microbial culture with high acidogenic activity
Authors: de la Torre Irma , Goma Gérard 
Published: December 2004

AbstractThe mixed cultures which were used were isolated from municipal sludge digesters, and the production of organic acids (acetic, propionic, butyric, etc.) from carbohydrates was tested. The behavior of the reference population (culture R) obtained directly from the sewage treatment plant, is compared to that obtained after three months in a plug‐flow reactor (Gradostat fermentor) without pH control (culture A) and after six months with pH control (culture B). For culture B, the specific rate of acid production is related to the cell growth rate by (1/X)rp= 17 µ + 1.6 with a maximal acid concentration of 40 g/liter. The batch culture yields are improved from 0.36g/g for the initial culture (R) to 0.72 g/g for culture B after six months in continuous culture, and 0.8 g/g in plug‐flow continuous culture. The productivity of organic acids reaches 1.7 g/liter·hr. It is suggested that the acidogenic fermentation, the first step of methanogenesis, is a potential process to produce acetic, propionic, and butyric acids.
Alcoholic fermentation: On the inhibitory effect of ethanol
Authors: Novak M. , Strehaiano P. , Moreno M. , Goma G. 
Published: December 2004

AbstractThe inhibitory effect of ethanol is studied during alcoholic fermentation in strict anaerobiosis (initial dissolved oxygen stripped by gasing pure nitrogen). It is demonstrated that the ethanol produced during the batch fermentation is more inhibitory than the added ethanol (in the range of 0 to 72.6g/liter). By analogy with noncompetitive enzyme kinetic inhibition, the inhibition constant for added ethanol is 105.2 g/liter and 3.8 g/liter for produced ethanol, which exhibits the same inhibition effects in all experiments where ethanol was added. The measurement of the intracellular alcohol concentration can explain the dual inhibitory effects of ethanol.
Regulation phenomena in methanol consuming yeasts: An experiment with model discrimination
Authors: Bajpai R. K. , Reuß M. , Held W. 
Published: December 2004

AbstractAssimilation as well as dissimilation of methanol in yeasts takes place through its oxidative intermediate formaldehyde which is several times more toxic to the growth of microorganisms than methanol itself. Still, the role of formaldehyde, produced during methanol assimilation, upon growth of yeasts is not clear. In the present paper, an attempt has been made to throw some light upon this aspect. Starting with a basic frame work for methanol uptake by yeasts, several models were developed assuming different modes of regulation of key enzymes by methanol and/or formaldehyde. The main feature of the basic framework consists in consideration of two routes for oxidation of formaldehyde to CO2, one associated and the other not associated with production of energy. Further, the rate of energy production form the energy‐associated oxidation of formaldehyde is assumed to be controlled by the rate of energy consumption by anabolic reactions. The models were discriminated by subjecting these to biological constraints. As a result, the successful model suggests that in spite of higher inherent toxicity of formaldehyde, methanol exerts the controlling influence upon growth under normal conditions.
Dialysis continuous process for ammonium lactate fermentation: Simulated prefermentor and cell‐recycling systems
Authors: Stieber R. W. , Gerhardt Philipp 
Published: December 2004

AbstractA generalized mathematical model, previously developed and experimentally validated, was modified and used to computer‐simulate the outcomes of adding two systems for increasing the concentration of cell mass in the fermentor, and thereby the rate and extent of substrate conversion, in a dialysis continuous process for the ammonium lactate fermentation of deproteinized whey. The addition of a nondialysis continuous prefermentor would not improve the process. However, the addition of cell retention time would be reduced ninefold, and the extent of converting substrate to product would be increased 25% and accomplished almost entirely by maintenance metabolism.
Enzyme deactivation in fixed bed reactors with michaelis‐menten kinetics
Authors: Do Duong D. , Weiland Ralph H. 
Published: December 2004

AbstractRate expression for enzyme poisoning which are consistent with a Michaelis‐Menten main reaction are used to analyze the performance of a fixed bed reactor containing immobilized enzyme. When enzyme deactivation results from the irreversible bonding of a product molecule to an existing substrate‐enzyme complex, it is shown that minimum enzyme activity can occur in the interior of the bed, well away from the ends. This suggests that bed sectioning techniques may enable direct evaluation of fundamental poisoning mechanisms.
Stabilization of chloroplast by radiation‐induced immobilization with various glass‐forming monomers
Authors: Youshii F. , Fujimura T. , Kaetsu I. 
Published: December 2004

AbstractThe effect of immobilization with various glass‐forming monomers on the stability of PS II activity of spinach chloroplast was investigated. PS II activity (O2 evolution due to the Hill reaction) was reduced very slightly by the addition of monomers including polyethyleneglycol (PEG). Immobilization of chloroplast was done with hydrophobic monomer as well as hydrophilic monomer and activity of immobilized chloroplast increased with decreasing monomer concentration as far as the polymerization was possible. The activity of immobilized chloroplast was very high and it decayed far more gradually with the storage time in comparison with the decay of unimmobilized chloroplast and was retained more than 30 days. The optimum monomer concentration for immobilization was about 10%. Thermostability of chloroplast also increased greatly by immobilization with these monomers, especially hydrophilic monomers.
Use of the centrifugal separation technique in manufacturing a bioinsecticide based on Bacillus thuringiensis
Authors: Zamola Branimir , Valles Paolo , Meli Giuseppe , Miccoli Pietro , Kajfež Franjo 
Published: December 2004

AbstractWe have examined the possibility of separating residual Bacillus thuringiensis medium from crystal endotoxin and determined an optimal flow rate of fermentation broth through a disk centrifuge in order to make a total separation of the residue of nutritive medium, containing pathogenic toxins, from the endotoxin and spores.
Bioenergetic analysis of mixotrophic growth in Chlorella vulgaris and Scenedesmus acutus
Authors: Ogawa Takahira , Aiba Shuichi 
Published: December 2004

AbstractThe specific growth rate of Chlorella vulgaris in the presence of glucose (mixotroph) was always larger than that in autotroph when the light intensity was less than 10 klux. However, Scenedesmus acutus behaved differently, i.e., when the light intensity was more than 6 klux, the specific growth rate in mixotroph became smaller than that in autotroph. Cellular contents of chlorophyll a and b in Scenedesmus acutus that deteriorated more markedly in mixotroph than those of Chlorella vulgaris could account for these different growth behaviors. In other words, mechanisms relevant to the photosynthesis and the oxidative phosphorylation of glucose seem to function independently with respect to Chlorella Vulugaris.
Fermentors with the power introduced by aerating gas
Authors: Viesturs U. E. , Sturmanis I. A. , Krikis V. V. , Prokopenko V. D. , Erickson L. E. 
Published: December 2004

AbstractIn the present work methods and results of investigations on optimal construction of fermentor elements by multifactor planning at a random number of levels of any factor are presented. The optimal design of column fermentor of 0.02–100 m3 volume with sieve plates containing downcomers and with power introduced by aerating gas has been worked out. Several alternative designs have been compared by examining mass transfer rates, power requirements, and other operating characteristics. Several fermentor designs with the power introduced by aerating gas are discussed with respect to their performance for cultivating various microorganisms (yeast and bacteria).
Procedure for isolation of Thienamycin from fermentation broths
Authors: Treiber Laszlo R. , Gullo Vincent P. , Putter Irving 
Published: December 2004

AbstractAn improved process for the isolation of thienamycin, produced by the actinomycete Streptomyces cattleya, has been developed. The isolation procedure consists of three chromatographic steps, volume reduction by reverse osmosis between the steps, and freezedrying for obtaining the final product. The chromatographic steps are as follows: (1) ion exchange chromatography on Dowex 1 × 2 resin in the bicarbonate cycle, (2) gel chromatography on Dowex 1 × 2 resin in the chloride cycle, (3) reverse phase chromatography on XAD‐2 resin. This procedure is useful for processing large volumes of fermentation broth.
Alcohol fermentation of sweet potato. Membrane reactor in enzymatic hydrolysis
Authors: Azhar A. , Hamdy M. K. 
Published: December 2004

AbstractUse of Ultrafiltration membrane systems in stirred cell and in thin‐Channel systems for immobilizing enzyme (sweet potato intrinsic and β‐amylase) in hydrolysis of sweet potato through a continuous operation mode were studied. Both the filtration rate and reducing sugars, produced as the result of enzymatic hydrolysis, decreased with the filtration time. The immobilized enzymes in the thin‐channel system showed a much better performance compared to that in the stirred cell system. Addition of crystalline sweet potato β‐amylase to the sweet potato increased both the filtration rate and reducing‐sugars content. Alcoholic fermentation of the filtrate resulted in an alcohol content of 4.2%. This represented fermentation of 95% of the sugars with an efficiency of 88%.
Variation of bagasse crystallinity and cellulase activity during the fermentation of Cellulomonas bacteria
Authors: Enríquez A. , Montalvo R. , Canales M. 
Published: December 2004

AbstractA characteristic behavior of the fermentation process was observed during the growth of Cellulomonas on sugarcane bagasse. At the early stage of the fermentation the crystallinity index of bagasse increased, suggesting that the major metabolized fraction corresponded to the hemicellulose during this stage. Some time later the crystallinity achieved a steady state and then deceased, which indicated that the most complex structure of bagasse was being attacked. The analysis of the cellulolytic activity of extracellular enzyme in the medium showed a sharp increase followed by an abrupt leveling off and decline in activity. These results along with the reduction of crystallinity index and bagasse utilization (70%) justify the assumption that the C1 component was present in the cellulase complex synthesized by the bacteria.
Membrane reactor for enzymatic hydrolysis of cellobiose
Authors: Hong J. , Tsao G. T. , Wankat P. C. 
Published: December 2004

AbstractA pressurized, stirred vessel attached with an ultrafiltration membrane was used as a membrane reactor, Cellobiose hydrolysis by cellobiase was carried out and theoretically analyzed in terms of steady‐state conversion and flow rate through the membrane. When the flow rate exceeds a critical value, a significant fraction of the enzyme inside the reactor is localized in the concentration polarization layer where shear from stirring is high. Consequently, enzyme deactivation inside the concentration polarization layer is accelerated and the conversion decreases due to an exchange of active enzyme in bulk with deactivated enzyme in the polarization layer via convection and back diffusion. Successful operation can be obtained at flow rates lower than the critical point to avoid the polarization and thus the deactivation. It is shown that 6.5 L of 2 mg/mL of cellobiose solution is hydrolyzed to glucose with a conversion of 91% in 20 h with 1.617 mg of cellobiase enzyme, in a reactor attached with a PM 10 membrane of an effective surface area of 39.2 cm2.
Kinetics of multiproduct fermentations
Authors: Lam Jeffrey C. , Ollis David F. 
Published: December 2004

AbstractA simple model for biomass, product, and substrate evolution proposed previously for batch polysaccharide fermentations is extended to multiproduct fermentations. The examples involve Clostridium thermocellum, (ATCC 27405) fermentations of glucose to four products (ethanol, acetic, formic, and lactic acid), of fructose to two products (ethanol and acetic acid), and of cellobiose to two products (ethanol and acetic acid). In all cases, parameter evaluation was carried out in a serial deterministic procedure.