GROWTH EFFICIENCY OF SACCHAROMYCES-CEREVISIAE ON GLUCOSE ETHANOL MEDIA WITH A SMOOTH CHANGE IN THE DILUTION RATE (A-STAT)/

The effects of the ethanol/glucose ratio on the growth characteristics (mu(max), Q(O2)(max), Y-XS, Y-XO2, etc.) of Saccharomyces cerevisiae on mineral media were studied. The maximum specific growth rate of the strain, mu(max), obtained in a continuous culture with a smooth incre ase in dilution rate (A-stat) was equal to 0.44 h(-1) on glucose and 0 .13 h(-1) on ethanol mineral medium. The maximum value of the specific respiratory rate with six different glucose/ethanol ratios remained i n the range of 6-9 mmol O-2 h(-1) g dwt(-1). The residual concentratio n of ethanol up to concentrations of 4 g l(-1) did not reduce the resp iration rate markedly. The critical specific growth rate, mu(crit), (l (eth) = 0) was 0.25 h(-1) which was independent on the ethanol/glucose ratio in the Seed medium. Higher growth rates than mu > 0.25 h(-1) we re supported by the fermentative use of glucose. The maximum growth yi eld, Y-XS, increased from 0.57 on pure glucose to 0.68 on pure ethanol (C-mol C-mol(-1)). A practical maximum ratio of ethanol to glucose in Baker's yeast propagation was suggested to be 40-50% (C-mol C-mol(-1) ). (C) 1997 by Elsevier Science Inc.