摘要:

AbstractIn order to achieve high cell densities anchoragedependent cells are commonly cultured on microcarriers, where spatial restrictions to cell growth complicates the determination of the growth kinetics. To design and operate large‐scale bioreactors for microcarrier cultures, the effect of this spatial restriction to growth, referred to as contact inhibition, must be decoupled from the growth kinetics. In this article, a cellular automaton approach is recommended to model the growth of anchorage‐dependent cells on microcarriers. The proposed model is simple to apply yet provides an accurate representation of contact‐inhibited cell growth on microcarriers. The distribution of the number of neighboring cells per cell, microcarrier surface areas, and inoculation densities are taken into account with this model. When compared with experimental data for Vero and MRC‐5 microcarrier cultures, the cellular automaton predictions were very good. Furthermore, the model can be used to generate contact‐inhibition growth curves to decouple the effect of contact‐inhibition from growth kinetics. With this information, the accurate determination of kinetic parameters, such as nutrient uptake rates, and the effects of other environmental factors, such as toxin levels, may be determined. © 1994 John Wil

ISSN:0006-3592    

DOI:10.1002/bit.260430112

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

年代:1994

数据来源: WILEY

摘要:

AbstractAsn182 → AlaAspergillus awamoriglucoamylase expressed inSaccharomyces cerevisiaehad a first‐order thermodeactivation coefficient 40% that of wild‐type glucoamylase at pH 4.5 between 60° and 65°C, caused by the elimination of an Asn—Gly sequence subject to deamidation and eventual chain breakage. Above 70°C, and at pHs 3.5 and 5.5, thermodeactivation coefficients of wild‐type and mutant enzymes were roughly equal, because the fastest deactivation mechanism was no longer deamidation. The mutation had little effect on the enzyme's optimal pH for activity and subsite map, or on the glucose yield from starch dextrin hydrolysis. During enzyme production by yeast fermentation, highest cell densities and activities of wild‐type and mutant glucoamylases were attained after a period of glucose starvation, followed by a second addition of glucose. © 1994 John

ISSN:0006-3592    

DOI:10.1002/bit.260430113

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

年代:1994

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260430101

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

年代:1994

数据来源: WILEY