T. Kometani et al., NAD(P)H REGENERATION USING ETHANOL AS AN ENERGY-SOURCE IN BAKERS YEAST-MEDIATED BIOREDUCTION, Journal of fermentation and bioengineering, 77(1), 1994, pp. 13-16
A scheme for NAD(P)H regeneration from the corresponding oxidized form
through the oxidative pathway of ethanol in baker's yeast cells was s
tudied. Baker's yeast-mediated bioreduction of carbonyl compounds coup
led with the oxidative pathway of ethanol is efficient and clean compa
red with the earlier procedure using carbohydrates as the energy sourc
e. To study NADH regeneration, the bioreduction of acetol catalyzed by
NADH-dependent carbonyl-reducing enzymes was examined by using ethano
l or acetate as the energy source under several aeration conditions, i
ncluding an anaerobic environment. The results suggested that NAD+ for
med on the reduction of the carbonyl group was mainly regenerated as N
ADH through alcoholic oxidation into acetate. NADPH regeneration was t
hen studied in the same manner by examining the bioreduction of ethyl
acetoacetate catalyzed by NADPH-dependent carbonyl-reducing enzymes. T
he results suggested that NADPH was regenerated through acetate oxidat
ion into carbon dioxide. Thus, a total scheme for NAD(P)H regeneration
using ethanol as the energy source, coupled with bioreduction, was pr
oposed.