bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzyme immobilization by radiation‐induced polymerization of hydrophobic glass‐forming monomers at low temperatures
Authors: Kaetsu Isao , Kumakura Minoru , Yoshida Masaru 
Published: December 2004

AbstractEnzyme immobilization was studied by means of radiation‐induced polymerization of hydrophobic glass‐forming monomers at low temperatures. The polymerized hydrophobic composite was generally obtained in microspheric form. Enzymatic activity showed little decrease with repeated use in these systems. The particle size of the microsphere increased with increasing monomer concentration, and activity yield had a maximum at an optimum monomer concentration. Immobilization by copolymerization of hydrophilic and hydrophobic comonomers was also investigated and a maximum activity yield was found at a certain monomer concentration. A model scheme for immobilization at low temperatures was proposed and discussed.
Deacylation of benzylpenicillin by immobilized penicillin acylase in a continuous four‐stage stirred‐tank reactor
Authors: Carleysmith S. W. , Lilly M. D. 
Published: December 2004

AbstractImmobilized penicillin acylase has been used for the deacylation of benzylpenicillin at 37°C in a continuous reactor consisting of four 1 liter stirred tanks connected in series. There was good agreement between the predicted and actual conversions obtained in each tank under steady‐state conditions. The operational stability of the immobilized enzyme in the tanks depended on the pH and the rate of addition and concentration of alkali needed to neutralize the acid produced during the reaction. At pH 7 with the addition of 2M NaOH, the half‐life for enzyme stability was greater than 400 hr in all tanks. This was over half the value for the immobilized enzyme when stored at 37°C and pH 7.
Production and surface‐active properties of microbial surfactants
Authors: Margaritis A. , Zajic J. E. , Gerson D. F. 
Published: December 2004

AbstractA new source of surface‐active compounds produced by microbes was investigated. These biologically derived surfactants (biosurfactants) were found to be extracellular products of two newly isolated Corynebacterium species, which were gorwn on kerosene (Imperial Oil No.9). Batch‐growth kinetic studies were carried out in a 14 liter fermentor and the production of biosurfactants was found to be cell growth associated. The surface tension of the whole microbial broth was reduced to a minimum of about 30 dyn/cm, as compared with the surface tension for distilled water of 72 dyn/cm. The crude biosurfactants were recovered from the cell‐free broth, freeze‐dried, redissolved in water, and their surface‐active properties were studied. The biosurfactants reported here were found to be nontoxic and their ability to lower the surface tension of water was found to be comparable to that of sodium dodecylbenzene sulfonate, common commercial synthetic surfactant.
Algal single cell protein from wastewater treatment and renovation process
Authors: Moraine R. , Shelef G. , Meydan A. , Levi A. 
Published: December 2004

AbstractA Source of high‐quality protein for animal feed, based upon algae recovered in the process of upgrading waste oxidation pond effluents and promising to be particularly economical, is being developed at the Technion. Unlike other types of single cell protein(SCP), the algal protein does not have to return the full production cost but only that of concentration and final processing. The balance is shared by the value of waste disposal and the reclaimed water. Whereas such systems as activated sludge require considerable mechanical energy to supply the oxygen needed for aerobically degrading organics in wastewater, oxidation ponds utilize solar energy for that purpose. The sludge obtained when their effluents are clarified consists largely of algae, bacteria, fungi, and zooplankton in relative proportions varying with operating conditions, and contains 40–60%(dry basis) high‐quality protein. The high rate oxidation pond (a particularly intensive type of pond) produces on the average 34 g/m27sol;day solids, or over 100 tons/ha (hectare) annually. Two clarification routes have been found promising: centrifugation and alum flocculation followed by frothflotation. The latter route is less expensive in terms of both fixed and operating cost, and gives clarified effluent of higher quality, which can be seasonally stored with minimal eutrophication because the aluminum removes most of the phosphate from the effluent. A good product has been obtained by drum‐drying the concentrate, and preliminary feeding tests have indicated that it can replace at least 1/4 of the soymeal in broiler rations and 2/3 of the fishmeal in carp feed. No ill effect of the aluminum in the product recovered by alum flocculation has been found so far a process for removing and recycling the aluminum has been developed nonetheless, in case ill effects do show up in further tests. The combined value of the benefits derived from a system centered around the high‐rate oxidation pond with clarification by flocculation–flotation, in terms of waste treatment by alternative means, potable water saved, and soymeal replaced, significantly exceeds estimated cost.
Theoretical and experimental analysis of a soluble enzyme membrane reactor
Authors: Greco Guido , Alfani Francesco , Iorio Gabriele , Cantarella Maria , Formisano Angela , Gianfreda Liliana , Palescandolo Rosaria , Scardi Vincenzo 
Published: December 2004

AbstractRecently enzyme immobilization techniques have been proposed that are mainly founded on the formation of an enzyme–gel layer onto the active surface of an ultrafiltration membrane within an unstirred ultrafiltration cell. If the membrane molecular‐weight cutoff is less than the enzyme molecular weight and hence such as to completely prevent enzyme permeation (once the enzyme solution has been charged into the test cell and pressure applied to the system), a time progressive increase in enzyme concentration takes place at the upstream membrane surface that can eventually lead to gelation and hence to enzyme immobilization. However, depending on the total enzyme amount fed, the maximum enzyme concentration achieved in the unsteady state could be less than the gelation level. In this situation, no immobilization occurs and the enzyme still remains in the soluble form although it is practically confined within a limited region immediately upstream the membrane and at fairly high concentrations. In this paper, the experimental conditions that allow gelling to occur are discussed together with a theoretical analysis of the soluble enzyme membrane reactor which is obtained when no gelling takes place. Such a system could be usefully employed in performing kinetic analyses at high enzyme concentration levels that are still in the soluble form.
Mass‐transfer effects on the rate of isomerization of D‐glucose into D‐fructose, catalyzed by whole‐cell immobilized glucose isomerase
Authors: Boersma J. G. , Vellenga K. , de Wilt H. G. J. , Joosten G. E. H. 
Published: December 2004

AbstractThe investigated catalyst system consists of immobilized Arthrobacter cells containing the enzyme glucose isomerase, which catalyzes the isomerization of glucose into fructose. The internal structure of the catalyst was determined from electron microscope photographs of replicas of freeze‐etched catalyst. On the basis of the photographs a model for the internal structure of the catalyst was proposed. This structure was subsequently used to describe the reaction including mass‐transfer effects. It appeared that under normal operating conditions the external mass‐transfer rate does not influence the overall rate of reaction. The effect of internal mass‐transfer resistances on the overall reaction rate can well be accounted for by the socalled porous sphere model. The intrinsic kinetics of the isomerization catalyzed by the present catalyst system can be represented by a modified Michaelis–Menten equation for a reversible one‐substrate reaction.
Growth of Spirulina maxima on cow‐manure wastes
Authors: Oron Gideon , Shelef Gedaliah , Levi Anna 
Published: December 2004

AbstractExperiments were carried out on culturing the blue‐green alga Spirulina maxima on raw cow‐manure wastes in an outdoor pond. Improved growth was obtained at pH above 9.2 and temperature above 32°C, with half the radiation intensity required for other green algal species. A yield of 3 g/liter, in terms of total suspended matter, was achieved. The main advantage of this method is that S. maxima removes nutrients and thus serves as an alternative protein source.
Concentration of baboon endogenous virus in large‐scale production by use of hollow‐fiber ultrafiltration technology
Authors: Weiss S. A. 
Published: December 2004

AbstractA process is described in which the baboon endogenous virus (BaEV) is produced under optimum conditions in cell culture, and concentrated by hollow‐fiber ultrafiltration technology under conditions of large‐scale production. This system has advantages over conventional systems in that the flow rate is increased 2.5‐fold during concentration. Thermal inactivation of BaEV was retarded by the addition of lactose glutamate to the harvested tissue culture fluid. After concentration, at least 91% of the virus RNA‐directed DNA polymerase is recovered with a concomitant increase in infectious virus. Materials needed for modifying described systems may be obtained from commercial sources.
Mechanism of the enzymatic hydrolysis of cellulose: Effects of major structural features of cellulose on enzymatic hydrolysis
Authors: Fan L. T. , Lee Yong‐Hyun , Beardmore David H. 
Published: December 2004

AbstractThe susceptibility of cellulose to enzymatic hydrolysis is affected by the structural features of cellulosic materials. It has been suggested that the crystallinity and surface area of cellulose fibers are the most important structural features in this regard. This study investigated in depth the relative effects of these two structural features upon the enzymatic hydrolysis of cellulose and the change of the structural parameters of cellulose during the course of hydrolysis. It was found that the hydrolysis rate is mainly dependent upon the fine structural order of cellulose which can best be represented by the crystallinity rather than the simple surface area. Monitoring the changes in the structural parameters during the course of reaction showed that surface area is not a major limiting factor that slows hydrolysis in its late stages as has been suggested. This information concerning structural features is used to elucidate the mode of action of cellulase.
Extraction of hemicellulose from ryegrass straw for the production of glucose isomerase and use of the resulting straw residue for animal feed
Authors: Chen W. P. , Anderson A. W. 
Published: December 2004

AbstractThe hemicellulose fraction of ryegrass straw was extracted with NaOH and used for the production of glucose isomerase by Streptomyces flavogriseus. The level of hemicellulose extracted increased proportionately with increasing NaOH concentration up to about 4%, then the rate of increase slowed down. Hemicellulose extraction was facilitated by the combined application of heat and NaOH. Approximately 15% hemicellulose (12% as pentosan) could be obtained by treating straw with 4% NaOH for either 3 hr at 90°C or 24 hr at room temperature. The highest level (3.04 units/ml culture) of intracellular glucose isomerase was obtained when the organism was grown at 30°C for two days on 2% straw hemicellulose. The organism also produced a high yield of glucose isomerase on xylose or xylan. The NaOH‐treated straw residue, after removal of hemicellulose, had approximately 75% higher digestibility and 20% higher feed efficiency for weanling meadow voles than untreated straw. Thus, the residue could be used as animal feed. A process for the production of glucose isomerase and animal feed from ryegrass straw was also proposed.
Continuous production of bacitracin by immobilized living whole cells of Bacillus sp.
Authors: Morikawa Yasushi , Karube Isao , Suzuki Shuichi 
Published: December 2004

AbstractWhole cells of Bacillus sp., a bacitracin‐producing bacteria, were immobilized in polyacrylamide gel. The continuous production of bacitracin by an immobilized whole‐cell‐containing air‐bubbled reactor was examined with 0.5% peptone solution. The bacitracin productivity (28 units/ml/hr) obtained with this system was higher than that with a batch system. The effluent bacitracin concentration increased with increasing aeration rate and reached a steady‐state maximum above the aeration rate of 3.0 liter/min. A high bacitracin productivity was retained for at least eight days when the gel was washed with sterilized saline at a flow rate of 250 ml/hr for 2 hr once a day. The half‐life of the immobilized whole‐cell system was about 10 days. Bacitracin productivity by the immobilized whole‐cell reactor was higher than that by a conventional continuous fermentation process at high dilution rates.
Enhancement of cellulose accessibility and enzymatic hydrolysis by simultaneous wet milling
Authors: Kelsey Rick G. , Shafizadeh Fred 
Published: December 2004

AbstractIt has been shown that the rate of enzymatic saccharification of cellulosic materials including “pure” cellulose (Whatman CF−11 cellulose), newsprint, lignocellulose (prehydrolyzed to remove hemicelluloses), and wood can be substantially increased by simultaneous wet milling. An enhanced hydrolysis rate was sustained above that observed for ball milling: providing a more extensive saccharification. The cellulosic substrates were wet milled with a variety of grinding elements, such as sand, glass beads, and stainless‐steel beads, agitated in a shaker bath. Simultaneous hydrolysis was achieved with a 2% substrate slurry in a 0.1M acetate buffer at 45°C and pH 5. The effectiveness of this process was dependent upon the lignified matrix of the cellulose microfibrils, the grinding elements, and the oscillation frequency of the shaker bath. Wet milling “pure” cellulose for 48 hr, with 3.5 mm glass beads and 200 oscillations/min (opm), yielded 1031 mg reducing sugar/g substrates (93% saccharification) as compared to 483 mg (44%) for the ball‐milled sample and 253 mg (23%) for the unmilled material. With the lignified substrates stainless‐steel beads (3.5 mm) were more effective than glass. For lignocellulose 529 mg sugar/g substrate (93% saccharification) could be obtained by wet milling with cellulase for 24 hr. This was about three times greater than that of the ball milled (169 mg, 30%) and 10 times greater than that of the unmilled (52 mg, 9%) substrates. The method was also effective for wood particles (60 mesh) giving 143 mg sugar/g wood (approximately 38% saccharification) in 48 hr, whereas the ball‐milled sample gave only 79 mg (21%) and the unmlilled substrate 38 mg (10%). These observations can be explained on the basis of the current crystalline theory for the morphology of the cellulosic microfibrils. The advantage of wet milling and simultaneous hydrolysis apparently depends on a continuous generation of accessible sites and sustained rapid hydrolysis rate as the saccharification proceeds, where in the pretreated substrates the hydrolysis rate slow down as the active sites are reduced.
Cellobiose hydrolysis by endoglucanase (glucan glucanhydrolase) from Trichoderma reesie: Kinetics and mechanism
Authors: Ladisch Michael R. , Gong Cheng‐Shung , Tsao George T. 
Published: December 2004

AbstractGlucanohydrolase from Trichoderma reesei, having a molecular weight of 52,000, was evaluated for kinetic properties with respect to cellobiose. Results from this work include: (1) initial rate studies that show that glucanohydrolase hydrolyzes cellobiose by a competitive mechanism and that the product, glucose, inhibits the enzyme; (2) low‐pressure aqueous liquid chromatography that shows that formation of a reversion product, cellobiose, is minor and occurs in detectable amounts only a very high (90mM) cellobiose concentrations; (3) development of an equation based on the mechanism of glucanohydrolase action as determined by initial rate kinetics, which accurately predicts the time course of cellobiose hydrolysis; (4) derivation of an initial rate expression for the combined activity of cellobiase and glucanohydrolase on cellobiose. Based on data in this paper it is shown that the difference in inhibition pattern of the two enzymes could be used for determining the contamination of one enzyme by small quantities of the other.
Properties of soluble and immobilized Aspergillus niger β‐xylosidase
Authors: Oguntimein Gbekeloluwa B. , Reilly Peter J. 
Published: December 2004

AbstractAspergillus niger β‐xylosidase was characterized when in soluble form and when immobilized to alkylamine porous silica with glutaraldehyde and to alumina with titanium tetrachloride. Energies of activation averaged 13.4 KcaL/mol for the soluble enzyme, 9.0 Kcal/mol when immobilized to alumina, and 8.0 Kcal/mol when bound to silica. The highest activity of all forms of β‐xylosidase was found near pH 3. The soluble enzyme was highly stable at pH 4, where lowest rates of decay occurred, and temperature of 65°C and below. The decay rates of alumina‐bound β‐xylosidase and pH 4 and equivalent temperatures were approximately 10 times as high. Michaells constants were 0.200 and 0.262mM for o‐nitrophenyl‐β‐D‐xylopyranoside with soluble and alumina‐bound β‐xylosidase, respectively.
Production and utilization of Bacillus thuringiensis
Authors: Couch T. L. , Ross D. A. 
Published: December 2004

AbstractBiological insecticide formulations based on the entomogenous bacterium. Bacillus thuringiensis, have begun to be used widely in agriculture. This spore‐forming bacillus can be grown in submerged culture and formulated to provide stable agricultural formulations compatible with aerial and ground application systems. The safety of these products to nontarget organisms and man is responsible for the growing interest in their use on a variety of crops including pastures and forests. No longer a laboratory curiosity, B. thuringiensis is an economic alternative to chemical insecticides.
Infectivity and mode of action of Baculoviruses
Authors: Granados Robert R. 
Published: December 2004

AbstractThe genus Baculovirus contains three subgroups of viral types: (1) nuclear polyhedrosis viruses (NPVs), (2) granulosis viruses (GVs), and (3) nonoccluded baculoviruses. While little information is available for viruses from the third subgroup, several aspects of the infectivity and mode of action of NPVs and GVs have been studied. The most common route of entry of a virus into an insect host is per os, and both virus types enter midgut cells (primary site of infection) by membrane fusion. However, two distinct mechanisms of virus uncoating occur among the baculoviruses: NPVs uncoat within the nucleus, whereas GVs uncoat at the nuclear pore complex. Baculoviruses of subgroup 3 appear to uncoat by either mechanism. In addition to replicating within the nucleus, NPV inoculum virus may pass through the intestinal epithelium immediately after ingestion, thereby establishing a systemic infection of the hemocoel prior to virus replication in midgut cells. The GVs do not appear to pass through midgut cells as rapidly as NPVs and in general, the developmental cycle of GVs is longer than that of NPVs. NPVs have been grown in cell culture while GVs have not.
Energy requirements and process design considerations in compression‐milling pretreatment of cellulosic wastes for enzymatic hydrolysis
Authors: Tassinari Thomas , Macy Charles , Spano Leo , Ryu Dewey D. Y. 
Published: December 2004

AbstractThe effectiveness of compression‐milling pretreatment of lignocellulosics for enzymatic hydrolysis has been demonstrated for a wide variety of substrate sources. Reductions in the degree of crystallinity and the degree of polymerization of cellulose and partial destruction of the structural integrity of lignocellulosics brought about by compression milling significantly increase the susceptibility of cellulose to enzymatic hydrolysis. The enzymatic hydrolysis yield was found to be directly related to the specific energy input to the cellulosic substrate (kWh/1b substrate) by compression milling, and the energy input can be controlled by the milling time. The enzymatic hydrolysis yeilds from cellulosic materials pretreated by compression milling also vary significantly depending on the source and kind, the composition milling also vary significantly depending on the source and kind, the composition (contents of lignin and other components), and the structure. The power requirements for compression milling which renders equivalent hydrolysis yields also depend on the source and kind of lignocellulosics to be pretreated. For newspaper, the specific energy input required for 55% sugar yield is estimated as 0.3 kWh/lb substrate including 15% power loss. The additional sugar yield gained from the enzymatic hydrolysis of compression‐milled newspaper (over and above the sugar yield of untreated substrate) is determined as 453 g sugar/kWh energy input.
Fermentation of Bacillus thuringiensis for exotoxin production: Process analysis study
Authors: Holmberg Andrea , Sievänen Risto , Carlberg Gunnel 
Published: December 2004

AbstractThe exotoxin produced by certain serotypes of Bacillus thuringiensis was used as a means of microbiological control of the larval development of flies. The optimal batch cultivation conditions with respect to pH, temperature, aeration, agitation, and initial concentration of growth‐limiting substrate were determined. A dynamic model describing the process was designed and fitted to the experimental data. The application of a method for estimating exotoxin and bacterial concentrations from on‐line measurable quantities such as oxygen consumption and heat production is presented.
Product formation in the continuous culture of microbial populations grown on carbohydrates
Authors: Baskir Cyril Isadore , Hansford Geoffrey Spearing 
Published: December 2004

AbstractExperimental studies of the growth of a natural microbial population on a synthetic liquid effluent containing sugar, sodium alginate, and nutrients showed that: (I) the concentration of substrates in the feed to an activated sludge process exerts a significant effect upon its effluent chemical oxygen demand (COD) and (ii) there is an optimum sludge age for achieving minimum effluent COD, given by the relationship: optimum growth rate ∝ (feed COD)0.5. These were explained by incorporating the concept of product formation into existing activated‐sludge theory, which showed that at sludge ages longer than optimum, effluent COD increased due to product formation; at shorter sludge ages, the effluent COD increased owing to an increased concentration of degradable substrates.
Substrate utilization kinetic model for biological treatment process
Authors: Chen Y. R. , Hashimoto A. G. 
Published: December 2004

AbstractThe applicability of Contois' kinetic equation to aerobic and anaerobic treatments of organic wastes is investigated. A refractory coefficient to account for the nonbiodegradable portion of the organic substrates in the digester is incorporated into the kinetic equation. The kinetic equation is applied to the data for aerobic digestions of organic substrates and for anaerobic treatment of dairy wastes. They all show a very good fit of the kinetic equation to the data. Furthermore, the kinetic parameters and the refractory coefficients are shown to be independent of influent organic substrate concentration. This study confirms previous reports that the effluent quality of biological treatment systems for organic wastes depends on influent organic waste concentration. The effect of temperature on the kinetic parameters and the refractory coefficient for anaerobic treatment of sewage sludge are studied. It shows that the kinetic parameters vary with temperature, while the refractory coefficient remains fairly constant. Equations to predict biodegradable treatment efficiency and volumetric substrate utilization rate are also briefly discussed.