bluuebunny/crossref_metadata_2025_split huggingface dataset:
An immobilized α‐galactosidase continuous flow reactor
Authors: Reynolds John H. 
Published: December 2004

AbstractAn α‐galactosidase which will hydrolyze the oligosaccharides melibiose, raffinose, and stachyose has been immobilized on nylon microfibrils suitable for use in large flow‐through reactors. This catalyst system is stable for many months, both under use and storage conditions. The immobilized enzyme behaves similarly to the enzyme in solution, characteristically exhibiting both product and substrate inhibition. The catalyst is prepared in situ and a large, 8‐liter reactor has been made. The catalyst has been used to reduce the raffinose concentration in beet sugar molasses.
Gel entrapment of enzymes: Kinetic studies of immobilized glucose oxidase
Authors: Hinberg I. , Kapoulas A. , Korus R. , O'Driscoll K. 
Published: December 2004

AbstractGlucose oxidase (EC 1.1.3.4, from Aspergillus niger) has been entrapped in a crosslinked 2‐hydroxycthyl methaerylate gel containing 20% poly(vinyl pyrrolidone). The kinetic behavior and thermal stability of the entrapped enzyme were found to closely approximate that of the free enzyme. The entrapped glucose oxidase shows a broadened pH profile which is attributed to a buffering effect of the gel. Stability of gel entrapped glucose oxidase is extremely good at room temperature, suggesting a variety ofanalytical and control uses for this system.
Growth of microorganisms on chemically synthesized carbohydrate (“formose”) syrups
Authors: Bok Song Hae , Demain Arnold L. 
Published: December 2004

AbstractFormose syrup was studied as a carbon source for growth of a series of microorganisms obtained from various collections. Approximately 80 strains of bacteria, yeasts, and molds were inoculated into a medium containing formose syrup and mineral salts supplemented with small amounts of yeast extract and casein hydrolysate to supply accessory growth factors. Two preparations of formose syrup, produced by two different laboratories, were employed. Formose syrup I, characterized by a low sugar content, was poorly utilized; syrup II, containing a higher sugar concentration, was utilized to a greater extent. Two strains of Aerobacter acrogenes yielded 1.3 g dry cell mass from an initial charge of 10 g of formose II solids, whereas growth on 10 g of D‐glucose amounted to 3.7 g.Klebsiella aerogenes MIT‐B44, the best microbial strain isolated from soil by an enrichment technique, produced 1.3 g cells from 10 g fromose syrup II solids in supplemented medium; in direct comparisons, it produced 10–15% more cell 0.7–0.9 g cells per 10 g formose and grew with a doubling time of 55–70 min. Under such conditions, its macromolecular composition was 52% protein, 22% RNA, and 2% DNA. Although the apparent yield of cells from formose was only 8–11%, the actual yield based on formose utilized was 30%, the same as observed with glucose.A second strain was isolated from soil by enrichment with spent broth from K. aerogenes. This unidentified gram‐negative, short rod‐shaped bacterium grew in mixed culture with strain MIT‐B44; in unsupplemented media they produced 1.55 g cells from 10 g formose II solids and 2.9 g cells from 10 g glucose.
The preparation of immobilized lactase and its use in the enzymatic hydrolysis of acid whey
Authors: Weetall Howard H. , Havewala Noshir B. , Pitcher Wayne H. , Detar Clarence C. , Vann William P. , Yaverbaum Sidney 
Published: December 2004

AbstractThe enzyme β‐galactosidase (lactose) obtained from several microbial sources was immobilized on zirconia‐coated porous glass particles. The immobilized enzymes were characterized by determining pH profiles, kinetic constants, thermal profiles, and operationalhalf‐lives in lactose and whey ultrafiltrate solutions. Studies were carried out on continuous reactor performance, and enzyme requirements for scale‐up were estimated. Lactose or whey hydrolyzed by this technique could find use commercially as a sweetener in a number of dairy products.
Mechanism of cell disintegration in a high pressure homogenizer
Authors: G. Brookman James S. 
Published: December 2004

AbstractThe disintegration of baker's yeast (Saccharomyces cerevisiae) by a high pressure homogenizer, to a pressure of 25,000 psi. (172.37 MNm−2) is described, together with details of the methods of measurement used to obtain information on the valve movement and pressure transients. The theory of the mechanism of cell disintegration is discussed.
Hydrolysis of lactose in acid whey using β‐galactosidase immobilized on porous glass particles: Preparation and characterization of a reusable catalyst for the production of low‐lactose dairy products
Authors: Wierzbicki L. E. , Edwards V. H. , Kosikowski F. V. 
Published: December 2004

AbstractPartially purified lactoses (β‐D‐galactoside galactohydrolase, EC 3.2.1.23) from Aspergillus niger, Ladobacillus helveticus, and Saccharomyces lactis were immobilized on diazotized porous glass particles (mean pore diameter, 86.5 nm: particle size diameters, 75–125 μm). In acid whey containing 4–4.5% lactose, A. niger lactase gave the highest activity (89 μmoles lactose hydrolyzed/g glass, min) at 55°C and pH 4.5. Glass‐immobilized A. niger laclases (lactase‐BG) retained much hydrolytic activity after storage and periodic use for 165 days at 55°C. For values of X greater than 30%, hydrolysis of 0.12M lactose in acid whey by a continuous flow column packed with 2 ml of lactase‐BG particles could be correlated by X = 17.2(V/F) + 12.5 where X = lactose hydrolysis, percent of lactose originally present; V = volume of packed bed of lactase‐BG, ml; F = flow rate of acid whey, ml/min.
Response of the adenosine phosphate pool level to changes in the catabolic pattern of Saccharomyces cerevisiae
Authors: Akbar M. D. , Rickard Pamela A. D. , Moss F. J. 
Published: December 2004

AbstractChanges in the catabolic pattern of Saccharomyces cerevisiae, growing in continuous culture, were effected by altering the glucose feed rate or the dissolved oxygen concentration. The cytochrome concentrations and the adenosine phosphate pool level of the yeast in a series of steady states and during three transitions were measured and compared with the glucose uptake rate (QG), the respiration rate (QO2), and the rate of ethanolic fermentation (QE).Respiration was decreased at high glucose feed rates only if oxygen was low but cytochromes were glucose repressible at both high and low oxygen concentrations. In the main, QE and the levels of ATP, ADP, and AMP were decreased and cytochrome concentration were elevated at low QG values. No consistent relationship between any of the adenosine phosphate parameters and QO2 was discernible.Evidence is presented for the concept that the QG directly controls the adenosine phosphate pool level and that a relationship between the concentration of adenosine phosphate anhydride bonds and the adenosine phosphate level is constantly maintained.
A fiber‐optic retroreflective turbidimeter for continuously monitoring cell concentration during fermentation
Authors: Hancher C. W. , Thacker L. H. , Phares E. F. 
Published: December 2004

AbstractA fiber‐optic retroreflective turbidimeter has been developed to automatically and continuously assay the cell concentration in a fermentor by measuring the turbidity of the solution as a function of the light scattered at 180° to the incident light. The output signal is nearly directly proportional to the cell concentration in a fermentor when the sample stream contains from 0 to more than 50 g of cells per liter (wet weight). The device consists of a bifurcated fiber‐optics light pipe with its distal end inserted into a flow cell through which the material to be analyzed passes. A light source on one proximal branch of the light pipe illuminates the sample stream; light that is back‐scattered from participates in the stream re‐enters the light pipe and is returned to a photodetector on the other proximal branch of the light pipe. A signal conditioning system connected to the optical head by a cable provides gain and zero adjustment.
pH control and the “shoulder” effect in parallel fermentation pathways
Authors: Tanner Robert D. , Overley John R. 
Published: December 2004

AbstractIn an effort, to develop comprehensive mathematical models for use in optimizing fermentation processes, product rate data taken at constant pH's for the lactic acid fermentation (Lactobacillus delbrueckii) were analyzed. It was observed that the rate of acid synthesis‐time trajectories exhibited a “shoulder” effect at pH's less than 5. That is, a nearly constant rate of synthesis for up to 10 hr in the late growth phase, out of a maximum total fermentation time of 70 hr. This effect was used as a clue from which to structure the proposed model with parallel pathways. Simulating shunting pathways does, in fact, demonstrate that, the notion of parallelism is consistent with the expression of a shoulder. It is postulated, therefore, that a differential pH effect between two parallel pathways can account for the presence of a shoulder when both routes prevail, and no shoulder when either pathway predominates.
Properties and use of invertase entrapped in fibers
Authors: Marconi W. , Gulinelli S. , Morisi F. 
Published: December 2004

AbstractInvertase was entrapped in cellulose triacetate fibers and the properties of the insoluble derivative were studied. Fiber‐entrapped invertase was found very stable under operating conditions. For some insoluble preparations a half‐life value of 5,300 days was calculated; a sample of invertase fibers, continuously hydrolyzing sucrose, maintained unchanged its activity for five years. The activity displayed by invertase fibers was 15–65% of that of the free enzyme, depending on the amount of entrapped enzyme and on the porosity of the fibers. At very high substrate concentrations the activity of the entrapped invertase approximated to that of the free enzyme. The pH optimum for activity was around 4.5 for the free and entrapped invertase. The native and entrapped enzyme was unstable at temperatures higher than 35°C.The continuous hydrolysis of sucrose using invertase fiber was studied and the potential industrial application of entrapped enzyme is discussed.
Enzyme yields from cells of brewer's yeast disrupted by treatment in a horizontal disintegrator
Authors: Marffy Ference , Kula Maria‐Regina 
Published: December 2004

AbstractMaltase, phosphatase, malate dehydrogenase, glucose‐6‐phosphate dehydrogenase, and 6‐phosphogluconate dehydrogenase activities were determined in the supernatant of brewer's yeast cells from samples taken at various intervals during a 90 min treatment in a Dyno‐Mill disintegrator.In an attempt to find optimum operating conditions, the following parameters were varied: speed of rotation of the agitator, flow rate, yeast concentration in the slurry and bead diameter, and the specific rate of extraction was determined for each such variation. Analysis of the data showed that, superimposed upon extraction, there was a progressive but slow loss of total activities. Enzyme release could be expressed as an approximately first‐order chemical reaction. The results compared well with those of Follows et al. (Biotechnol. Bioeng.), 13, 549 (1971) and showed that the Dyno‐Mill can be operated under proper conditions without significant loss of enzyme activity and with high yields.
Optimization of the release of undegraded material extracted from cells by ultrasound
Authors: Coakley W. T. , Brown R. C. , James C. J. , Gould R. K. 
Published: December 2004

AbstractThe time course of release of intact labile material from cells by cavitating ultrasound is examined. Curves are presented which show the yield of intact subcellular components obtainable from cells as a function of sonication time for various values of the ratio of inactivation rate to release rate. The general cases where inactivation of released product is concentration dependent (chemical) and concentration independent (mechanical) are considered.For a flow system the time of attainment of equilibrium concentration of active product is analyzed as a function of flow rate, release rate, inactivation rate, and volume of chamber. Curves of optimal yields to be expected for batch and flow systems are presented. It is shown that sonochemical inactivation can be made negligible by sonication of high cell concentration suspensions.
Thermodynamics and rheology of the Hughes press
Authors: Scully D. B. , Wimpenny J. W. T. 
Published: December 2004

AbstractAmong the methods used for the rupture of cells by means of solid shear, the Hughes press is best known. It operates by forcing an aqueous suspension of cells previously frozen at −27°C under pressure through a narrow circumferential gap. The mode of action requires a knowledge of the isentropic compression of the solid phase and its possible involvement with a phase change from ice I to ice III. It is shown that the mechanical properties of the solid mixture are relevant. A model is proposed of the plastic flow for the geometry of the press and it is shown that cell breakage is proportional to the velocity of the plunger and inversely proportional to gap width.
Experimental studies on a kinetic model for design and operation of activated sludge processes
Authors: Gaudy A. F. , Srinivasaraghaven R. 
Published: December 2004

AbstractPrevious experimentation in our laboratory has shown that the classical theory developed for continuous growth of pure cultures in completely mixed aerobic systems in which the recycle cell concentration factor, c (where c = XR/X), is a selectable system constant, did not provide a suitable model for the heterogeneous (natural) populations of the activated sludge process. Another model was derived in which the recycle cell concentration, XR was employed as a system constant instead of c, and computational analysis was performed. Laboratory pilot plant experimentation was undertaken in order to determine whether a “steady state” in aerator biological solids concentration, X̄, and substrate concentration, S̄, could be approached under this mode of operation. Studies were performed at various organic feed concentrations holding dilution rate, D, at 0.125 hr−1, hydraulic recycle ratio, α, at 0.25, and XR at 10,000 mg/liter. Also, values of maximum specific growth rate, μmax, and saturation constant, Ks were determined. It was found that the model approached the steady state condition with heterogeneous populations more closely than did the classical model, and the high degree of treatment efficiency predicted by the model was demonstrated experimentally.
Mixing in anaerobic digestion
Authors: Verhoff F. H. , Tenney M. W. , Echelberger W. F. 
Published: December 2004

AbstractThe mixing of the anaerobic digester contents significantly influences the efficiency of this operation; in particular, hydraulic dead zones are extremely detrimental to the reaction kinetics involved in anaerobic digestion. An analysis of the relative importance of thermal fluid movement in the digester to those caused by fluid inflow and outflow is presented. As an example, these principles are applied to a digester at the South Bend Wastewater Treatment Plant. Experimental measurements, which have general applicability for the measurement of digester mixing volume, confirm the theoretical conjectures. Various types of optimizations can be attempted on this mixing operation. One such optimization applied to gas lift mixers, as employed in the South Bend Treatment Plant, is illustrated.
Degradation of lignin by combined chemical and biological treatment
Authors: Stern Arthur M. , Gasner Larry L. 
Published: December 2004

AbstractIt has been demonstrated that ozone dosages of 0.06 lb and 0.78 lb per pound of lignin can reduce the optical density (in the visible range) of the latter by 82% and 92%, respectively. The reduction in color is accompanied by a shift in the molecular weight distribution of lignin from a broad peak of between 20,000 and 70,000 to lower molecular weight, species including substantial amounts possessing a molecular weight of 1000 or less. The cost of decolorizing a typical kraft paper bleach effluent is estimated to be under 50¢/1000 gal which compares favorably with competitive decolorizing processes. Lignin ozonation results in the production of a series of decolorized products which can serve as the sole source of carbon for a variety of microorganisms. Feasibility studies indicated that at least 40% of the ozonated material can be transferred into microbial biomass (protein) as well as other products of commercial interest such as fumaric acid and penicillin.
Cost optimization of activated sludge systems
Authors: Middleton Andrew C. , Lawrence Alonzo W. 
Published: December 2004

AbstractActivated sludge is a widely used aerobic biological waste‐water treatment process. A rational approach to least cost design of an integrated system is described which includes the following processes: activated sludge reactor, final settling tanks, gravity thickening, and aerobic sludge digestion. Both capital and operation and maintenance costs are considered. Biological reactor design is based on microbial kinetic concepts and continuous culture of microorganisms theory. Biological solids retention time (θc) is utilized as the primary independent design variable to which system performance is related, e.g., effluent quality, ammonia oxidation, and excess sludge production. Liquid‐biomass separation is based on the batch flux technique, a rational approach to design of gravity separators (final settling tanks). Trade‐offs among reactor volume, clarifier size, recycle pumping capacity, thickener capacity, digester volume, air requirements, and sludge production are discussed. The optimum design is taken as the combination of these parameters within the acceptable design domain, determined by effluent quality criteria, that results in minimum cost. While the method described is general, design of a given treatment system depends on availability, from lab or pilot studies, of system specific numerical values for biological growth coefficients and biomass setting characteristics. A design example illustrates the approach.
The extended Kalman filter applied to a continuous culture model
Authors: Svrcek W. Y. , Elliott R. F. , Zajic J. E. 
Published: December 2004

AbstractThe temperature‐dependent endogenous metabolism model of single species continuous culture dynamics is utilized in the computer simulation of the Kalman filter state estimation technique. Parameters of the nonlinear equations can be “tracked” while variance in measured states can be damped. The state estimator is illustrated in, the context of conventional control strategies.
Large‐scale purification of Qβ‐virus by differential centrifugation
Authors: McGregor W. C. , Round J. J. , Ramel A. H. 
Published: December 2004

AbstractBacterial RNA virus, Qβ, has been purified in gram amounts by differential centrifugation. Final separation of the virus from host E. coli rRNA was based on the density differential in the pellet. The method provided a simplified alternative to the more conventional rate zonal or isopycnic zonal centrifugation techniques.
Growth of Spirulina maxima algae in effluents from secondary waste‐water treatment plants
Authors: Kosaric N. , Nguyen H. T. , Bergougnou M. A. 
Published: December 2004

AbstractSpirulina maxima, a high protein alga, was grown in effluents from the London municipal waste treatment plant. Optimum growth conditions were developed, the composition of algae and the removal of nitrogen and phosphorus in effluents were studied. The advantages of this process in tertiary waste‐water treatment and the quality of the single cell protein were investigated.
Affinity chromatography purification of diphtheria toxin
Authors: Cukor George , Readio Josephine D. , Kuchler Robert J. 
Published: December 2004

AbstractNAD was covalently linked to Sepharose‐4B using a 6 carbon spacer. Sterile, dialyzed spent culture medium containing 100 Lf/ml of diphtheria toxin or material concentrated by (NH4)2SO4 precipitation containing 1500 Lf/ml, was chromatographed on a column of NAD–Sepharose. Ultraviolet absorbing material which did not flocculate with diphtheria antitoxin was eluted with 0.02M phosphate buffer. When the elation buffer was changed to one containing 0.5M NaCl, purified toxin was eluted off the column.
Production of Sindbis, influenza, and vesicular stomatitis viruses in chicken embryo and rat embryo cell suspensions
Authors: Keay L. , Schlesinger S. 
Published: December 2004

AbstractStudies were carried out on the production of Sindbis, influenza and vesicular stomatitis viruses in suspensions of chicken embryo and rat embryo cells. The yield of Sindbis virus in chicken embryo cell suspensions was independent of the multiplicity of infection over the range 0.0001 to 0.01 although reduction in multiplicity caused a delay in virus production. With influenza virus the use of higher multiplicities gave increased virus yields possibly due to the very slow production at low multiplicities. In both monolayer and suspension cultures of chicken embryo cells addition of serum or use of media richer than minimum essential medium (Eagle) had little effect on Sindbis virus production, but if the glucose were omitted the virus yield was markedly reduced. In cell suspensions, a marked reduction in virus yield occurred if infection were delayed more than 24 hr after cell preparation whereas in monolayers the delay of infection allowed cell propagation and hence a higher yield of virus. It was also shown that vesicular stomatitis virus can be produced in chicken embryo cell suspensions, and that rat embryo primary cell suspensions can be used to prepare both Sindbis and vesicular stomatitis viruses. Sindbis virus obtained from chicken embryo cell suspensions was purified by polyethylene glycol precipitation and sucrose density gradient centrifugation and shown to contain only those proteins previously identified as viral, without any contamination from chicken cell proteins. The relative ease and economics of virus production by cell suspension and monolayer methods is compared.
A mild method of general use for covalent coupling of enzymes to chemically activated collagen films
Authors: Coulet Pierre R. , Julliard Jacques H. , Gautheron Danièle C. 
Published: December 2004

AbstractFilms of highly polymerized collagen, prepared in industrial conditions, were chosen for surface covalent binding of enzymes because of their insolubility, mechanical resistance, proteic nature, hydrophilic properties and for their abundance in chemically activable COOH. Untanned films, previously acid‐ methylated, were activated by acyl azide formation. After removal of reagents by repeated washing, the coupling of enzyme was performed by immersion of the activated film in the enzyme solutions (2 to 3 hr, 0°C). The procedure is particularly mild since the enzymes never come into contact with chemical reagents, and thus avoid all denaturing processes. All the enzymes tested were successfully bound: glutamate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase, glutamate pyruvate transaminase, creatine kinase, hexokinase, trypsin, and urease. As tested with aspartate amino transferase, enzymatic activity remained constant for months (100% after 5 months) in spite of repeated use of the film at 30°C, washing and storage in buffer at 4°C between assays.
Influence of intraparticle diffuisional limitation on the observed kinetics of immobilized enzymes and on catalyst design
Authors: Regan D. L. , Lilly M. D. , Dunnill P. 
Published: December 2004

AbstractNumerical solutions to the equations describing simultaneous mass transfer and enzymic reaction within porous spherical particles have been used to examine the effect of enzyme content and other parameters on the kinetic behavior of immobilized enzymes. These solutions have also been compared with experimental data for enzymes immobilized to DEAE‐cellulose particles. The influence of particle size and enzyme content on catalyst design is discussed.