摘要:

AbstractThe production of ethanol from cheese whey lactose has been demonstrated using a single‐stage continuous culture fermentation with 100% cell recycle. In a two‐step process, an aerobic fed batch operation was used initially to allow biomass buildup in the absence of inhibitory ethanol concentrations. In the anaerobic ethanol‐producing second step, a strain ofKluyveromyces fragilisselected on the basis of batch fermentation data had a maximum productivity of 7.1 g ethanol/L/h at a dilution rate of 0.15 h−1, while achieving the goal of zero residual sugar concentration. The fermentation productivity diminished when the feed sugar concentation exceeded 120 g/L despite the inclusion of a lipid mixture previous shown to enhance batch fermentation product

ISSN:0006-3592    

DOI:10.1002/bit.260260102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractGrowth ofAspergillus parasiticusand accumulation of aflatoxin B1in the medium that contained antifungal agents were monitored during the growth cycle of the mold. The antifungal agents tested are the food additive (antioxidant), butylated hydroxyanisole (BHA), the pesticide, isoprothiolane, and the antibiotic, nystatin. Growth of the mold was quantified using a newly developed criterion, named the growth coefficient (GC). The GC values were calculated from the growth parameters of the logistic function that fits the growth curve of the mold. At the range of concentrations of additives studied, maxima of growth inhibition were 31.3, 23.1, and 43.6% at 60 ppm of BHA, 70 ppm of isoprothiolane, and 45 units of nystatin/mL, respectively. The ability of the mold to accumulate aflatoxin B1in its medium [as measured by the accumulation rate constant (α)] In the presence of various levels of the antifungal agents was concentration‐dependent. Sixty parts per million of BHA decreased the value of α by 71.7%, 30 units of nystatin/mL was the most effective concentration of that antibiotic and resulted in only 23.5% inhibition, and isoprothiolane at all its levels stimulated elaboration of aflatoxin B1by the m

ISSN:0006-3592    

DOI:10.1002/bit.260260103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractFor the purpose of improving ethanol productivity, the effect of air supplement on the performance of continuous ethanol fermentation system was studied. The effect of oxygen supplement on yeast concentration, cell yield, cell viability, extracellular ethanol concentration, ethanol yield, maintenance coefficient, specific rates of glucose assimilation, ethanol production, and ethanol productivity have been evaluated, using a high alcohol tolerantSaccharomyces cerevisiaeSTV89 strain and employing a continuous fermentor equipped with an accurate air metering system in the flow rate range 0–11 mL air/L/h. It was found that, when a small amount of oxygen up to about 80μ mol oxygen/L/h was supplied, the ethanol productivity was significantly enhanced as compared to the productivity of the culture without any air supplement. It was also found that the oxygen supplement improved cell viability considerably as well as the ethanol tolerance level of yeast. As the air supply rate was increased, from 0 to 11 mL air/L/h while maintaining a constant dilution rate at about 0.06 h−1, the cell concentration increased from 2.3 to 8.2 g/L and the ethanol productivity increased from 1.7 to 4.1 g ethanol/L/h, although the specific ethanol production rate decreased slightly from 0.75 to 0.5 g ethanol/g cell/h. The ethanol yield was slightly improved also with an increase in air supply rate, from about 0.37 to 0.45 ethanol/g glucose. The maintenance coefficient increased by only a small amount with the air supplement. This kind of air supplement technique may very well prove to be of practical importance to a development of a highly productive ethanol fermentation process system especially as a combined system with a high density cell culture techn

ISSN:0006-3592    

DOI:10.1002/bit.260260104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe cellulase production from immobilizedTrichoderma reeseicomposites prepared by radiation polymerization at low temperature was studied. The production of cellulase from the cells irradiated by radiation was slightly retarded at the initial stage of the culture, but was immediately recovered. The production of cellulase resulting from the growth of the immobilized cells proceeds efficiently in the composite having a porous polymer matrix, in which the productivity of cellulase varied with the hydrophilicity, the shape of the composite, monomer, and cell concentration. It was found that cellulase produced by immobilized growing cell composites effectively hydrolyzed cellulosic wastes such as newspaper and chaff which are pretreated by irradiation and crushing.

ISSN:0006-3592    

DOI:10.1002/bit.260260105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractKinetic results on the glucomylase‐catalysed hydrolysis of maltose and maltotriose, and glucose polymerization into maltose and isomaltose up to 450 g/L total sugar concentration are presented. Whereas the enzyme has a faster hydrolytic and synthetic activity on α‐(1→4) than on α‐(1→6) linkages, at equilibrium, on the contrary, the isomaltose level which represents 15% (w/w) of the total sugar concentration at the highest investigated concentrations is much higher than the corresponding maltose level. Under a wide range of initial conditions, experimental results are adequately described by a new kinetic model with simple first‐ and second‐order, or Michaelian‐type, rate expressions for the reversible hydrolysis of maltotriose, maltose, and isomaltose. The model also accounts for the inhibition of hydrolysis by glucose, but does not consider the concentration of water which, under the present conditions, was not found kin

ISSN:0006-3592    

DOI:10.1002/bit.260260106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe feasibility of operating a multistage continuous culture of plant cells was demonstrated forNicotiana tabacum. Cells in the second stage of a two‐stage chemostat were morphologically distinct from cells in the first stage or cells in a single‐stage unit with a holding time equal to the combined holding times in the two‐stage system. Cells in the second stage produced much higher levels of phenolics per unit weight of cells than cells in either the first‐stage or single‐stage unit. The steady‐state was reproduced. When a glucose side stream was fed to the second stage, an increase in apparent cell division was observed with a simultaneous decrease in phenolics productivity. When the toxic precursor phenylalanine was pulsed into the reactor, the quantity of biomass decreased temporarily while phenolic productivity increased. These experiments demonstrate that multistage continuous culture may be useful in increasing secondary metabolite formation in cells and in exploring mechanisms controlling secondary metabolit

ISSN:0006-3592    

DOI:10.1002/bit.260260107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractSome properties of the crude lyophilized fibrinolytic enzyme produced byCochliobolus lunatusin surface culture were studied. Enzyme concentrations over the range from 0.16 to 10.16 mg/mL showed that concentration above a certain level ceased to be the limiting factor controlling enzyme action. At pH 6.8 and a temperature of 40°C, the fibrinolytic enzyme showed maximal activity at a human fibrin concentration of 2 mg/mL. The optimum pH values for enzyme activity were 6.98 and 7.0, using Sørensen and Mcllvaine buffers, respectively. Fibrinolytic enzymes were isolated from a static culture ofCochliobolus lunatus; isolation was carried out with various agents. Ammonium sulphate yielded the highest recovered fibrinolytic activity. The fraction salted out by precipitation at 25% ammonium sulphate saturation possessed the highest recovered fibrinolytic activity compared to the ammonium sulphate, ethanol, and acetone fraction

ISSN:0006-3592    

DOI:10.1002/bit.260260108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractAn endo‐β‐1,4‐glucanase (EC 3.2.1.4) was obtained in high yields in purified form a culture filtrate ofFusarium liniby an extremely simple method. The method consists of precipitation of the culture filtrate with ammonium sulphate (290 g/L), followed by chromatography of the precipitated fraction on Biogel P‐150. The purification is based on the unusual property of the enzyme being eluted after cytochrome C, even though it molecular weight is 2.8 × 104(by SDS PAGE). The yield of pure enzyme was 6.8 mg/L culture broth. The homogeneity of the enzyme was established by ultracentrifugation, isoelectric focusing, and electrophoresis in polyacrylamide gels containing SDS. The enzyme was isoelectric at pH 8.3 and contained 2.9% carbohydrate. TheKmvalue for carboxymethyl (CM) cellulose was 11.6 mg/mL. The enzyme showed high viscosity reducing activity towards CM cellulose but very low activity with Walseth cellulose and crystalline celluloses such as Avicel and cotton. The purified enzyme has activity towards xylan. The amino acid analysis showed a predominance of acidic and neutral amino acids and low contents of histidine, arginine, and methionine. One‐half of the cysteine content was 11 residues/mol enzyme, and no free–SH group w

ISSN:0006-3592    

DOI:10.1002/bit.260260109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractApproximately one‐half of the lignin and most of the hemicellulose present in agricultural residues such as wheat straw and corn stover are solubilized when the residue is treated at 25°C in an alkaline solution of hydrogen peroxide. The delignification reaction is most efficient when the ratio of hydrogen peroxide to substrate is at least 0.25 (w/w) and the pH is 11.5. The supernatant fraction from a given pretreatment, after addition of makeup peroxide and readjustment of the pH, can be recycled to treat at least six additional batches of substrate, resulting in a substantial concentration of hemicellulose and soluble lignin degradation products. Hydrolysis of the insoluble fraction withTrichoderma reeseicellulase after alkaline peroxide treatment yields glucose with almost 100% efficiency, based upon the cellulose content of the residue before treatment. These data indicate that alkaline peroxide pretreatment is a simple and efficient method for enhancing the enzymatic digestibility of lignocellulosic crop residues to levels approaching the theoretical maxim

ISSN:0006-3592    

DOI:10.1002/bit.260260110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe diffusion characteristics of several substrates of varying molecular sizes into and from Ca‐alginate gel beads in well‐stirred solutions were investigated. The values of the diffusion coefficient (D) of substrates such as glucose,L‐tryptophan, and α‐lactoalbumin [with molecular weight (MW) less than 2 × 104] into and from the gel beads agreed with those in the water system. Their substrates could diffuse freely into and from the gel beads without disturbance by the pores in the gel beads. The diffusion of their substrates into and from the gel beads was also not disturbed by increasing the Ca‐alginate concentration in the beads and the CaCl2concentration used in the gel preparation. In the case of higher molecular weight substances such as albumin (MW = 6.9 × 104), γ‐globulin (MW = 1.54 × 105) and fibrinogen (MW = 3.41 × 105), the diffusion behaviors of the substrates into and from the gel beads were very different. No diffusion of their substrates into the gel beads from solutions was observed, and only albumin was partly absorbed on the surface of the gel beads. The values ofDof their substrates from the gel beads into their solutions were smaller than their values in the water system, but all their substrates could diffuse from the gel beads. The diffusion of high molecular weight substrates was limited more strongly by the increase of Ca‐alginate concentration in the gel beads than by the increase of the CaCl2concentration used in the gel preparation. Using these results, the capacity of Ca‐alginate gel as a matrix of immobil

ISSN:0006-3592    

DOI:10.1002/bit.260260111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY