Premium
Influence of the ethanol and glucose supply rate on the rate and enantioselectivity of 3‐oxo ester reduction by baker's yeast
Author(s) -
ChinJoe Ifoeng,
Straathof Adrie J. J.,
Pronk Jack T.,
Jongejan Jaap A.,
Heijnen Joseph J.
Publication year - 2001
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.1161
Subject(s) - chemistry , fermentation , ethanol , yeast , ethanol fuel , enantiomeric excess , oxygen , biomass (ecology) , electron donor , ketone , organic chemistry , catalysis , biochemistry , enantioselective synthesis , oceanography , geology
Baker's‐yeast‐mediated reductions of ketones hold great potential for the industrial production of enantiopure alcohols. In this article we describe the stoichiometry and kinetics of asymmetric ketone reduction by cell suspensions of bakers’ yeast ( Saccharomyces cerevisiae ). A system for quantitative analysis of 3‐oxo ester reduction was developed and allowed construction of full mass and redox balances as well as determination of the influence of different process parameters on aerobic ketone reduction. The nature of the electron donor (ethanol or glucose) and its specific consumption rate by the biomass (0–1 mol.kg dw −1 .h −1 ) affected the overall stoichiometry and rate of the process and the final enantiomeric excess of the product. Excess glucose as the electron donor, i.e. a very high consumption rate of glucose, resulted in a high rate of alcoholic fermentation, oxygen consumption, and biomass formation and therefore causing low efficiency of glucose utilization. Controlled supply of the electron donor at the highest rates applied prevented alcoholic fermentation but still resulted in biomass formation and a high oxygen requirement, while low rates resulted in a more efficient use of the electron donor. Low supply rates of ethanol resulted in biomass decrease while low supply rates of glucose provided the most efficient strategy for electron donor provision and yielded a high enantiomeric excess of ethyl ( S )‐3‐hydroxybutanoate. In contrast to batchwise conversions with excess glucose as the electron donor, this strategy prevented by‐product formation and biomass increase, and resulted in a low oxygen requirement. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 29–38, 2001.