EFFECT OF CORN STEEP LIQUOR ON FERMENTATION OF MIXED SUGARS BY CANDIDA-SHEHATAE FPL-702

Candida shehatae FPL-702, is a mutant strain obtained from C. shehatae ATCC 22984 by selection for rapid growth on L-xylose and xylitol in t he presence of respiratory inhibitors. This strain produced more ethan ol from xylose than any other pentose-fermenting yeast strain tested. These included the parental C. shehatae strain ATCC 22984 and other wi ld-type or mutant strains of Pichia stipitis and Pachysolen tannophilu s. C. shehatae FPL-702 showed initial rapid growth on xylose. During f ed-batch shake-flask fermentation of glucose, FPL-702 produced 3.5% (w /v) ethanol. Ethanol. production from glucose increased to 5.0% (w/v) when corn steep liquor (CSI,) was added in the fermentation medium. In contrast, CSL reduced consumption of xylose and ethanol production in shake-flask fermentations of xylose and mixtures of xylose and glucos e. However, CSL also reduced xylitol formation. Maximum ethanol produc tion from a mixed-sugar fermentation was 3.25% (w/v). C. shehatae FPL- 702 did not use L-arabinose during mixed-sugar fermentation in the pre sence or absence of CSL, but it did grow on arabinose and convert it i nto arabitol. In the fed-batch reactor, this strain exhibited improved ethanol production rates from mixed sugar in the presence of CSL.