摘要:

AbstractA laboratory model constant‐depth film fermentor was developed. Film grew on the surface of polytetrafluoroethylene (PTFE) plugs and was limited to a predetermined depth by mechanically removing excess film. Six film‐forming organisms were isolated from river water and used to assess the operating characteristics of the fermentor. Film accumulation was logarithmic, and a steady state was maintained. Electron micrographs show early film development. The fermentor enables film to be grown on any substratum and allows discrete, reproducible, and representative samples to be ta

ISSN:0006-3592    

DOI:10.1002/bit.260320302

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

年代:1988

数据来源: WILEY

摘要:

AbstractA kinetic model of ethanol fermentation conducted under a variety of conditions in a continuous four‐stage reactor is proposed. The expressions for specific growth and product formation rates are:\documentclass{article}\pagestyle{empty}\begin{document}$$ \mu = \mu _0 {\rm exp( - }k_1 P){\rm (1 - }X/X_1) \\ \nu _P = \nu _0 {\rm exp( - }k_2 P){\rm (1 - }X/X_2) \\ $$\end{document}Parameters were identified by nonlinear programming and shown to fit data correctly for steady states of seven different experiments. The product inhibition constants were of 27 and 84 g/L, respectively. Secondary inhibitions were represented by the linear biomass term. The proposed model gave a better description of phenomena than one which only took ethanol inhibition into account. The same model also fitted batch fermentation data, with only some parameters altering significantly. The use of this model for on‐line purposes is discus

ISSN:0006-3592    

DOI:10.1002/bit.260320303

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this study, a cephalosporin C producing strain,Cephalosporium acremonium(ATCC 36225), was chosen to determine the optimal conditions that maximize antibiotic production in a mixed substrate of glucose and sucrose. A model for cell growth and cephalosporin C production at different pH and temperature was developed and the associated parameters were evaluated experimentally. Pontryagin's maximum principle, in conjunction with the model, was used to predict the optimal temperature and pH control profiles to maximize the production of antibiotic.

ISSN:0006-3592    

DOI:10.1002/bit.260320304

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

年代:1988

数据来源: WILEY

摘要:

AbstractPoly(styrene) microcapsules, prepared by depositing the polymer around emulsified aqueous droplets, were coated with a synthesized polyelectrolyte; i.e., copolymer of maleic acid (MA) with methyl vinyl ether (MVE), co‐poly(MA, MVE), or with styrene (St), copoly(Ma, St). The permeability of the capsule membrane was investigated under various pHs of the outer medium usingn‐propyl alcohol as a permeant. It became apparent that either copoly(MA, St)‐ or copoly(MA, MVE)‐coated microcapsules function as a pH‐sensitive capsule. In particular, the former showed a dramatic change of the permeability in response to small differences in pH (5–6). By reference to the viscometric and electrophoretic studies of both copolymers, these were interpreted as being due to a pH‐induced alteration of the configuration of the copolymer coating on the surface of the capsule membrane. When sucrose was hydrolyzed in an aqueous suspension of the copoly(MA, St)‐coated capsules into which invertase was loaded, the hydrolytic reaction was initiated at pH 5. 5 and stopped at pH 4. 5. Such initiation‐cessation control was repeated reversibly without dama

ISSN:0006-3592    

DOI:10.1002/bit.260320305

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

年代:1988

数据来源: WILEY

摘要:

AbstractAlcaligenes EutrophusH‐16 was grown in continuous culture under conditions which induced hydrogenase production. The hydrogenase enzyme was extracted, partially purified and immobilized on porous glass. This enzyme was then studied both in solution and in immobilized form as a possible candidate for a number of industrial applications. It proved to have a stability (storage and operational) which was highly temperature dependent. Temperatures near freezing caused the enzyme to retain its activity for long periods of time. Although its kinetics were more favorable at elevated temperatures of up to 40°C, the loss of stability outweighed this gain substantially. The effects of buffer type and pH on enzyme activity were also studied. This enzyme has only a modest sensitivity to destruction by oxygen during storage, in contrast to hydrogenases produced by several other microorganis

ISSN:0006-3592    

DOI:10.1002/bit.260320306

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn order to obtain further information on the behavior and optimal design of external‐circulation‐loop airlift (ECL‐AL) bioreactors, the liquid circulating velocity, gas holdup and average bubble diameter in the downcomer were studied using highly viscous pseudoplastic solutions of various types of CMC. A few comparative measurements also were made using a viscous Newtonian aqueous sucrose solution. For the liquid velocity measurements, an ultrasonic flow meter (Doppler frequency shift principle) was applied for the first time to the gas/non‐Newtonian liquid dispersion in downward flow and satisfactory results were obtained. For viscous liquids, the circulating liquid velocity in the riser section of an ECL‐AL (uLR) is shown to be dependent mainly on the downcomer‐to‐riser cross‐sectional area ratio (Ad/Ar), the effective viscosity (ηeff) and the gas superficial velocity (uGR) as described by the following equation\documentclass{article}\pagestyle{empty}\begin{document}$$ u_{LR} = 0.23u_{GR}^{0.32} (A_d /A_r)^{0.97} \eta _{eff}^{ - 0.39} $$\end{document}The circulating liquid velocity exerts opposing effects on the mass transfer and liquid‐phase mixing performances of ECL‐AL fermentors. Therefore, it is proposed that the optimum operating conditions for a given fermentation may be best achieved by means of independently regulating the circula

ISSN:0006-3592    

DOI:10.1002/bit.260320307

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

年代:1988

数据来源: WILEY

摘要:

AbstractEffective oxygen diffusion coefficients and solubilities were measured for submerged cultures ofSaccharomyces cerevisiae, Escherichia coli, andPenicillium chrysogenum. Both effective oxygen diffusion coefficients and solubilities were found to decrease with increasing cell concentrations in the fermentation media. Comparison of the experimental results of effective oxygen diffusion coefficients in fermentation media with values theoretically predicted on the assumption of unpenetrable microbial cells indicates that oxygen molecules diffuse through the cells during the diffusion process. Within the cell concentration range of typical submerged fermentations, the effective oxygen diffusion coefficient of the fermentation media can be described asDe=A1f+A2f2. In this equation,fis the cell volume fraction and bothA1andA2are functions of the shape of the cells and the ratio of effective oxygen diffusion coefficient in microbial cells to that in the medium.

ISSN:0006-3592    

DOI:10.1002/bit.260320308

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

年代:1988

数据来源: WILEY

摘要:

AbstractA scaleup study of the radial streaming chromatography (ZetaPrep technique) using hybridoma culture supernatant as model protein solution is described in this article. Lab and pilot cartridges were tested. Scaleup factors were calculated from the lab experiments and compared to the data obtained at pilot level. The procedure consists of three different steps: microfiltration, diafiltration, and the ZetaPrep technique using QAE cartridges. Diafiltration was used to condition the clarified culture supernatant. Calculating the elution volumes for the pilot level (ZetaPrep 800) from the smallest lab cartridge (ZetaPrep 15), a difference between calculated and experimental values of 230% was obtained. The difference between calculated and experimental values using results from ZetaPrep 100, a preparative cartridge, was 120%. At pilot level it is possible to purify 10 L culture supernatant within 3 h including regeneration and reequilibration of the cartridge. This procedure is useful for monoclonal antibodies (mAb) with a low isoelectric point (pl). The pl's of the mAb which was used in this work are in the range 5.4–6.

ISSN:0006-3592    

DOI:10.1002/bit.260320309

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe have performed controlled fed‐batch fermentation experiments to compare the production level of hepatitis B surface antigen (HBsAg) by recombinant yeastSaccharomyces cerevisiaestrains (YNN27/pYBH‐1, YNN27/ p2μ‐S11, YNN27/pDCB‐S2) containing plasmid vector with alcohol dehydrogenase (ADH1), acid phosphatase (PHO5), and glyceraldehyde‐3‐phosphate dehydrogenase (GPD) promoter, respectively. Yeast cell concentrations of 15‐35 g dry cell weight/L were obtained. By limiting phosphorous concentration, HBsAg expression level for the YNN27/p2μ‐S11 strain with inducible PHO5 promoter reached 0.2–0.3 mg/L. By controlling nutrient addition rate and dissolved oxygen concentration, HBsAg concentrations of 3‐10 mg/L were achieved in 60–70 h fermentation using the YNN27/pDCB‐S2 strain with the

ISSN:0006-3592    

DOI:10.1002/bit.260320310

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

年代:1988

数据来源: WILEY

摘要:

AbstractSome properties of the cellulolytic complex obtained fromTrichoderma reeseiQM 9414 grown on Solka floc as carbon source and its ability to hydrolyze the lignocellulosic biomass ofOnopordum nervosumBoiss were studied. The optimum enzyme activity was found at temperatures between 50 and 55°C and pH ranging from 4.3 to 4.8. Hydrolysis of 4‐nitropnenyl‐β‐D‐glucopyranoside (4‐NPG) and cellobiose by the β‐glucosidase of the complex, showed competitive inhibition by glucose with aKivalue of 0.8 mMfor 4‐NPG and 2. 56 mMfor cellobiose. Enzymatic hydrolysis yield ofOnopordum nervosum, evaluated as glucose production after 48 h, showed a threefold increase by pretreating the lignocellulosic substrate with alkali. When the loss of glucose incurred by de pretreatment was taken into account, a 160% increase in the final cellulose to glucose conversion was found to be due to

ISSN:0006-3592    

DOI:10.1002/bit.260320311

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

年代:1988

数据来源: WILEY