摘要:

AbstractIn the microbial production of useful products, it is important to understand the allocation of substrate energy for maintanance, growth, and product formation. Methods are presented to obtain point and 95% confidence interval estimates for the true growth yield parameter, true product yield parameter, and the maintenance parameter. Methods are presented which allow all data to be used simultaneously for those cases where more than the minimum number of measurements are made at each specific growth rate (or dilution rate). Three estimation methods and two forms of the energy allocation equations are investigated. Point estimates are similar for the three methods, but interval estimates are considerably larger for one of the three methods. The results depend on the form of the equations.

ISSN:0006-3592    

DOI:10.1002/bit.260250302

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of mild sulfuric acid (H2SO4) hydrolysis on the cellulosic components of piggery slurry was investigated. Combinations of acid concentrations between 1 and 10% (w/v) and temperatures of 89, 90, and 100°C were studied with the aim of maximizing the release of soluble carbohydrates from the cellulosic constituents of piggery slurry. The highest yield of soluble monosaccharides was obtained by hydrolysis with 5% sulfuric acid at 90°C for 3 h, which produced 0.53 g of monosaccharide for every gram of cellulosic material available in raw piggery slurry. When the fungusSporotrichum pulverulentumwas cultivated on a medium prepared from this hydrolysate, a yield of 19.8 g of microbial biomass was obtained for each liter of piggery slurry hydrolyze

ISSN:0006-3592    

DOI:10.1002/bit.260250303

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

年代:1983

数据来源: WILEY

摘要:

AbstractA continuous process involving simultaneous saccharification and fermentation of liquefied starch has been developed usingZymomonas mobilis. Amyloglucosidase retention and cell recycle have been effected by using an Amicon hollow‐fiber membrane system with a MW cutoff of 5000. Relatively high productivities of up to 60 g L−1h−1have been achieved at ethanol concentrations of 60–65 g/L. The system also offers the potential for reduced enzyme requirements for saccharif

ISSN:0006-3592    

DOI:10.1002/bit.260250304

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

年代:1983

数据来源: WILEY

摘要:

AbstractNα‐Palmitoyl‐L‐lysyl‐L‐lysine‐ethyl ester dihydrochloride (PLL) has antimicrobial properties and may be useful as a food preservative. This study was conducted to see if PLL can inhibit growth and synthesis of aflatoxin byAspergillus parasiticus. Growth of mold and accumulation of aflatoxins were monitored for up to 15 days. To compare these data with those of a known inhibitor of aflatoxin synthesis, dichlorvos was added to media, and mold growth and aflatoxin accumulation were monitored. The kinetic model of Brown and Vass that correlates growth and formation of secondary metabolites was applied to results of this study, and values for maturation time (tm) and aflatoxin accumulation rate constant (α) were calculated. Values oftmdecreased when cultures contained PLL, whereas presence of dichlorvos resulted in a considerable increase. The lag phase of mold growth increased in the presence of PLL. The values of α increased with an increasing amount (up to 300 ppm) of PLL in media. Higher concentrations of PLL decreased the value of α. All levels of dichlorvos tested decreased the value of α. The aflatoxin accumulation rate constant (α) as a function of concentration of additive (C) followed the general equation:\documentclass{article}\pagestyle{empty}\begin{document}$$\alpha = \frac{{\alpha _m C\exp (- {C \mathord{\left/ {\vphantom {C {K_i }}} \right. \kern-\nulldelimiterspace} {K_i }})}}{{C + K_a }}$$\end{document}where αm,Ka,

ISSN:0006-3592    

DOI:10.1002/bit.260250305

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

年代:1983

数据来源: WILEY

摘要:

AbstractA novel technique for settling microorganisms has been described. The technique involves adding a dense, inert powder to a suspension of microorganisms under conditions where flocculation of the microorganism with the inert poweder occurs. The flocs formed are small and relatively dense and settle rapidly. Suspensions ofSaccharomyces cerevisiaeyeast have been flocculated with several different inert seed materials achieving rapid settling and separations of up to 99.9%. Nickel powder was used as a seed material for most experiments described here, and iron sand showed promise as a cheaper seed for large‐scale use. The degree of flocculation and cell separation obtained depended largely on the seed concentration and the components in solution. Temperature and pH had little effect. When the method was initially applied to a practical fermentation, flocculation was poor because of inhibiting compounds in the fermentation medium, but modification of the technique produced good flocculation in the mediu

ISSN:0006-3592    

DOI:10.1002/bit.260250306

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

年代:1983

数据来源: WILEY

摘要:

AbstractA new technique is outlined for the rapid settling of yeast cells in fermentation media. The technique involved the addition of dense, inert particles (nickel powder) to a yeast suspension (Saccharomyces cerevisiae) at pH 4.5 and a rapid change of pH to 8.0–9.0. When the pH was changed large flocs formed immediately and settled rapidly, leaving a clear supernatant. On returning the pH to 4.5 the flocs were destroyed. This technique gave larger flocs and higher settling rates than the constant pH method, and much lower nickel/yeast ratios were required. Good flocculation also occurred in a fermentation medium. The technique was used to recycle yeast cells to a semicontinuous ethanol fermentation. Application of the technique to this and similar systems is discussed. The factors affecting yeast/inert powder flocculation are also discussed and a model is proposed to explain the observed experimental behavior for flocculation with a rapid change in p

ISSN:0006-3592    

DOI:10.1002/bit.260250307

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

年代:1983

数据来源: WILEY

摘要:

AbstractStyrene–methacrylic acid copolymers of varying combinations crosslinked withp‐DVB (1–2%) and porous structure were synthesized to be used as carriers in trypsin immobilization. The styrene–methacrylic acid copolymers containing free carboxy groups were activated by conversion into the mixed carbonic anhydride withN‐ethoxycarbonyl‐2‐ethoxy‐1,2‐dihydroquinoline (EEDQ) at pH 4.0. The degree of activation of copolymers were determined from the amount ofp‐aminobenzoic acid each could bind. The activated copolymers were incubated with trypsin in phosphate buffer (pH 8.0) at 4°C for 24 h. The optimum conditions for enzymatic activity measurements determined and the activity tests were carried out in 1.5 × 10−2MCaCl2solution (pH 8.0) at 0.05 ionic strength with a pH‐stat instrument. The dependence of the activity of styrene–methacrylic acid (SMA)/trypsin derivatives to pH was investigated and it was observed that the optimum pH of the immobilized trypsin derivatives moved to the basic region compared to the native trypsin. It was found that as the ionic strength increased, the shift in the optimum pH decreased and the activity increased. The Michaelis constants for the SMA–trypsin derivatives were determined with aid of Lineweaver–Burk diagrams. The thermal, storage, and operational stabilities of SMA–trypsin derivatives were assessed. It was found that the above stabilities for all the immobilized trypsin derivatives were better

ISSN:0006-3592    

DOI:10.1002/bit.260250308

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

年代:1983

数据来源: WILEY

摘要:

AbstractFive different types of reactors were employed for glucose isomerization using shrimp shell as the support on which to immobilize the glucose isomerase. The Michaelis–Menten constants and effective diffusivity of glucose in the immobilized enzyme bed were experimentally determined and used in a theoretical analysis of the radial‐flow reactor. The fractional conversions of the radial‐flow, fluidizedbed, and packed‐bed reactors with the same ‐residence time were found experimentally to be almost the same. This result reveals that the use of radial‐flow and fluidized‐bed reactors for this immobilized enzyme system is hi

ISSN:0006-3592    

DOI:10.1002/bit.260250309

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe characteristics of horseradish peroxidase (HRP) immobilized onto Sepharose by a photochemical‐initiated graft copolymerization are presented. Active copolymers were synthesized using different amounts of glycidylmethacrylate (GMA), bisacryloylpiperazine (BAP), or 1,3,5‐hexhydrotriacryloyl‐s‐triazine (HTsT) as functional monomer. The activities, theK′mvalues (pGMA) copolymers: 0.53–0.76 × 10−4M; pBAP copolymers: 0.90–1.4 × 10−4; pHTsT copolymers: 1.8–2.6 × 10−4Mand the thermal stabilities of the enzyme copolymers were strictly connected to the type of polymer. By varying the polymer amount present in a given copolymer, significant differences were found in the thermostability properties of pBAP and pHTsT copolymers both when checked in water or in phosphate buffer. No differences were found for pGMA copolymers. The samples in which there are the lowest pBAP or pHTsT content resulted the most stable. The activity retained after 240 min at 60°C by free HRP and pGMA–HRP was 30% whereas by pBAP–HRP and pHTsT‐HRP it was 50 and 75% of the original. Operational stability of the materials was in agreement with thermostability data. These results are discussed in terms of enzyme microenvironment which is strongly affected by the differen

ISSN:0006-3592    

DOI:10.1002/bit.260250310

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis article is concerned with the development of a model to plan a strategy for an enzymatic batch process where enzyme is subjected to deactivation described by the inverted linear decay model. The particular system studied is the enzymatic hydrolysis of penicillin to 6‐amino penicillanic acid (6 APA), but the model can be utilized with other batch systems as long as the decay of the immobilized enzyme (IME) preparation is described by the inverted linear decay model. The model developed is eminently practical and simple and several example of its application are shown. Experimental data obtained in a small pilot plant batch recirculated reactor on the average are well fitted by this model. For IME systems whose decay is best described by the first‐order decay model, it is not possible to use the same appro

ISSN:0006-3592    

DOI:10.1002/bit.260250311

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

年代:1983

数据来源: WILEY