Isolation of thermotolerant, osmotolerant, flocculating Saccharomyces cerevisiae for ethanol production

Four thermotolerant, osmotolerant, flocculating alcohol producing cultures of Saccharomyces cerevisiae were isolated from soil samples collected from a thermal power plant in India. All the isolates grew at 44°C but VS1 and VS3 were better than the other two. Maximum ethanol yields obtained from 150 g/l glucose were 75 and 60 g/l using culture VS3 at 30°C and 40°C, respectively. Growth and ethanol production were decreasing at 44°C so higher temperatures were not tested, but the isolates could tolerate temperatures above 44°C. All cultures belonged to class IV flocculating yeasts and were able to tolerate up to 350 g/l glucose. These cultures have economical importance for use in alcohol production during hot seasons in countries such as India.