摘要:

AbstractA nondestructive method of measuring extracellular polysaccharides (ECP) in activated sludge floes using Ruthenium Red dye adsorption was developed at the Environmental Engineering Laboratory at the University of Colorado at Boulder. The effects of pH, buffer solution, dye concentration, sludge mass, temperature, and incubation time on dye adsorption was determined. Ruthenium Red dye adsorption to bacterial floes was found to fit a Brunauer–Emmett–Teller (BET) isotherm model. Of the other environmental conditions in the system, pH was found to have the strongest effect on dye adsorption to bacterial flocs. The amount of extra cellular polysaccharides (ECP) measured by Ruthenium Red adsorption was compared with extracellular polysaccharides measured by two chemical extraction methods. Of all methods considered Ruthenium Red dye adsorption measured the highest amount of extracellular polysaccharide with the lowest amount of bacterial cell disruption. Thus, Ruthenium Red dye adsorption was more effective than extraction procedures for measurement of extracellular polysaccharides in activated sludge fl

ISSN:0006-3592    

DOI:10.1002/bit.260330802

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

年代:1989

数据来源: WILEY

摘要:

AbstractDirect saccharification of 2.64% cassava starch byRhizopus oligosporus145F was attempted under various cultural conditions. Maximum glucose yield of 18.0 g/L culture filtrate was obtained with an initial pH 3.8, 2% (v/v) inoculum ofR. oligosporusspores, and an incubation temperature of 45°C in shake flask cultures for 48 h. This concomitantly produced 2.7 g mycelia/100g cassava starch containing 20.2% true protein. The production of glucose and mycelia was accomplished with 92.8% starch saccharification having 67.9% starch to glucose conversion efficiency

ISSN:0006-3592    

DOI:10.1002/bit.260330803

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

年代:1989

数据来源: WILEY

摘要:

AbstractA continuous enzymatic hollow fiber reactor (HFR), obtained by immobilizing cellobiose active cells into the shell side of hollow‐fiber modules, was studied. The HFR yield was monitored by glucose analysis resulting from hydrolysis of cellobiose. The residence time of substrate in the bioreactor to obtain convenient hydrolysis yields was calculated from tests carried out by varying the reactor dilution rate in the range 0.001–0.004 L/min. The glucose yield was measured for 300 h (continuous substrate flux). The yield decreased from 40 to 15%. This decrease was due to the loss of specific activity in the operating conditions and to the pressure drop increase from 0.2 to 1.7 atm. The pressure drop increase is in turn dependent on the cell loading (0.2–2.1 g dry cell) and the substrate

ISSN:0006-3592    

DOI:10.1002/bit.260330804

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

年代:1989

数据来源: WILEY

摘要:

AbstractA general theory is presented in this article for determining the intrinsic rate constants for the main reaction and deactivation reaction, the effective diffusivity of the substrate, and the active enzyme distribution within porous solid supports from deactivation study of a continuous stirred‐basket reactor (CSBR). For the parallel deactivation five reaction kinetics are considered: (a) Michaelis–Menten, (b) substrate inhibition, (c) product inhibition (competitive), (d) product inhibition (anticompetitive), and (e) zero‐order kinetics. The experimental results of the system of hydrogen‐peroxide‐immobilized catalase on controlled‐pore glass particles are analyzed to demonstrate the application of the theory developed for parallel deactivation of active immobilized enzyme (IME). For series deactivation only first‐order kinetics is treated, and a numerical procedure is proposed to deter mine the rate parameters and the internal active enzyme distribution. The experimental data of the system of glucose‐immobilized glucose oxidase on silica‐alumina and controlled‐pore glass particles are used t

ISSN:0006-3592    

DOI:10.1002/bit.260330805

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

年代:1989

数据来源: WILEY

摘要:

AbstractExpression kinetics of the human Epidermal Growth Factor (hEGF) from the α‐factor prepro region in a 2‐μm based plasmid was studied inSaccharomyces cerevisiae. Production of hEGF was highly medium de pendent as a chemically defined, nonenriched media had a significantly lower yield than did enriched media. Also cells grown on yeast nitrogen base without amino acids with casamino acids degraded the hEGF after cell growth as opposed to a yeast extract, peptone, and dextrose (YEPD) medium, which elicited no measurable extracellular proteolysis of the hEGF. α‐factor directed production kinetics of hEGF on the YEPD medium were growth associated, secretion limitations and extracellular degradation were negligible, and the hEGF was nearly 100% selectively secreted. With sufficient agitation, shake flask experiments were representative of aerated controlled batch fermentations. No effect of high cell density was observed on cell growth or hEGF production kinetics. The hollow fiber bioreactor had no direct effect on the substrate or protein yields ofS. cerevisiae, however the low oxygen transfer capacity of the membrane was not sufficient to support res

ISSN:0006-3592    

DOI:10.1002/bit.260330806

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

年代:1989

数据来源: WILEY

摘要:

AbstractA quantitative study of the influence of initial serum concentration on hybridoma growth rate, maximum viable and total cell yield, and specific antibody production rate is presented. The specific growth rate varied in a Monod fashion with initial serum levels (2–10% FCS), givingKm= 1.6 v/v% and μmax= 0.92 d−1. The maximum cell yields (total and viable) were linear with initial serum level, indicating stoichiometric as well as kinetic limitation by serum component(s). The specific antibody production rate for each individual run fitted well to a non‐growth‐associated model. However, the non‐growth‐associated parameter varied monotonically with initial serum concentration, suggesting the catalytic role of serum component(s) in antibody production. Also, glutamine was utilized inefficiently, with at least a third of it secreted back into the culture supernate in the form of glutamate. While very simple model equations describe the specific growth and product formation rate for an individual batch run, the larger picture indicates need for a more detailed unstructured or stru

ISSN:0006-3592    

DOI:10.1002/bit.260330807

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe kinetics of cell growth and foreign protein production, as well as factors affecting protein stability, were studied and optimized in batch and fed‐batch fermentations of a recombinant strain ofEscherichia coli.The pL promoter from bacteriophage lambda under the control of a temperature‐sensitive cl represser, with the entire construct integrated into theE. colichromosome through the use of a defective bacteriophage lambda lysogen, was used to direct the synthesis of T4 DNA ligase. The biphasic fermentations consisted of a primary growth phase at 30°C followed by an induction phase which was initiated by shifting the temperature to 42°C. In the fed‐batch fermentations, additional nutrients were added at the time of initiating induction. Maintenance of sufficiently high concentrations of the organic substrates (glucose and casamino acids) during the induction phase was required for continued cell growth at 42°C. Such growth was essential for T4 DNA ligase formation andin vivostability. Hence, fed‐batch fermentations produced the highest yield of the foreign protein Commensurate with providing lower total amounts of substrates. In such cases, high cell densities (6 g dry wt/L) with substantial intracellular levels of T4 DNA ligase (4.6% total cellular protein, or 2.7% of the dry biomass) wer

ISSN:0006-3592    

DOI:10.1002/bit.260330808

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

年代:1989

数据来源: WILEY

摘要:

AbstractSeveral on‐line optimizing control strategies were proposed and tested by computer simulation for the efficient operation of bioreactors. The control task was divided into two, one of which was to search for the optimal operating point and passed the set point to the lower layer of which task was to make the process output follow the set point as soon as possible. It was shown to be effective for the upper layer to express the objective function as a polynomial with respect to the measurement variable and to make use of it for finding the optimum point. Noting that the major dynamic characteristics of bioreactor system is the time‐varying and nonlinear nature, the adaptive type control system is in evitable. It was shown to be quite effective to use discrete type self‐tuning PID controller and the optimal controller compensated for the interaction between the control loops.Application was made to the cell recycle system for the production of lactic acid and baker's yeast cultivation. I was found from the former application that the control quality can be significantly improved by incorporating the decoupling strategy into the lower layer closed‐loop system. It was also found from the latter application that the initial startup period can be significantly reduced by making use of the rough mathematica

ISSN:0006-3592    

DOI:10.1002/bit.260330809

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

年代:1989

数据来源: WILEY

摘要:

AbstractCell growth and enzyme (α‐amylase) production characteristics ofBacillus subtilisTN106 containing the recombinant plasmid pAT5 are investigated in batch and continuous cultures using a defined medium with glucose as the limiting nutrient. The batch culture studies demonstrate that the recombinant plasmid, reported earlier1to be stably maintained in the host, suffers from segregational and structural instabilities. The structural instability of this strain occurred during culture storage and can be eliminated in bioreactor experiments by using a modified inoculum preparation procedure. Such elimination allows an unbiased investigation of segregational instability via continuous culture studies. Such studies conducted with this fast growing microorganism, in the absence of antibiotic selection pressure, indicate a very efficient glucose utilization (very low residual glucose concentrations) over a wide range of dilution rates (0.16 h−1– 0.94 h−1). The nearly time–invariant and low residual glucose concentrations at each such dilution rate enable convenient estimation of growth parameters of the host and recombinant cells and frequency of segregational instability from transients in the resulting mixed cultures. The specific α‐amylase activity exhibits an inverse relationship to the specific growth rate of recombinant cells. The growth of recombinant cells is not affected by the presence of antibiotic (kanamycin). The growth advantage of host cells over recombinant cells diminishes with increasing

ISSN:0006-3592    

DOI:10.1002/bit.260330810

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

年代:1989

数据来源: WILEY

摘要:

AbstractFor saving energy in antibiotic production and reducing the amount of agricultural wastes, solid state fermentation was used in this study to produce tetracycline with sweet potato residue byStreptomyces viridifaciensATCC 11989. It was found that the optimal media for tetracycline production were sweet potato residue 100 g, organic nitrogen (rice bran, wheat bran, or peanut meal) 20 g, (NH4)2SO42.4 g, KH2PO40.4 g, CaCO31.8 g, NaCl 0.6 g, MgCl20.8 g, soluble starch 10 g, methionine 0.2 g, histidine 0.8 g, and monosodium glutamate 1.6 g with initial moisture content 68–72%, and initial pH 5.8–6.0. Each gram of dry weight substrate was inoculated with 1.0 × 108conidia and incubated at 26°C for 5–7 days, producing 4720 μg of total tetracycline equivalent potency. When incubated at 26°C with the initial moisture content 68%, the conidia in solid media germinated on the second day, mycelia grew abundantly on the third day and reached stationary phase on the sixth day. The antibiotic production was consistent with the morphogenesis ofS. viridifaciens: activity could be detected on the third day, had the maximal potency on the sixth day, and decreased slightly on the tenth day. (11

ISSN:0006-3592    

DOI:10.1002/bit.260330811

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

年代:1989

数据来源: WILEY