Isolation and identification of yeast strains producing high concentration of ethanol with high viability

摘要

To isolate yeast strains producing high concentration of ethanol. 125 strains were subjected to screening. Initially 14 strains able to grow in a medium containing 15 percent(v/v) ethanol, 7 strains capable of growing in a medium containing 50 percent (w/v) glucose, 23 strains having relatively fast fermentation rates. 13 strains able to grow at 42 deg C were selected. After secondary screening, 11 strains having relatively high initial fermentation rate and producing high concentration of ethanol were selected. After tertiary screening 5 strains producing high concentration of ethanol were selected. These 5 strains were tested again for their ethanol production, residual sugar, and viability using fermentation medium containing 25 percent glucose. The strain producing the highest concentration of ethanol was 20-1 strain which produced 10.56 percent (w/v) (13.4 percent, v/v) ethanol in 4 days, and the highest viable strain was 11-1 which produced 10.35 percent (w/v) ethanol(13 percent, v/v) with the viability of 30.44 percent after 5 days of fermentation. Both of the 20-1 and 11-1 strains were identified as Saccharomyces cerevisiae.