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 degrees 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 degrees C and 40 degrees C, respectively. Growth and ethanol production were decreasing at 44 degrees C so higher temperatures were not tested, but the isolates could tolerate temperatures above 44 degrees 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. (C) 1999 Elsevier Science Ltd. All rights reserved.