Ethanol From Thermotolerant Yeast

A commercial yeast strain Saccharomyces cerevisiae was mutated by Gamma radiation to impart ability to hyper-produce ethanol and simultaneously increase its thermostability. Two approaches were employed for obtaining the desired phenotypes of the wild or native organism. Out of mutagenizing Gamma-ray dose, 1 kGy was selected as the best exposure dose for effective mutant selection and that first expression using larger cell volume of exposed cell population was more effective and was finally employed for getting the desired genotypes and mutant derivative finally selected was designated as M-9.This improved mutant was selected in the laboratory and semi commercial scales. The mutant strain proved more productive with respective to ethanol i.e., 7.5 % (w/v), 95.4 % (w/w) of the theoretical yield and 9.4 (w/v) cell mass and consumed almost all sugars i.e.; 98.6% (w/v) at 43 oC. The mutant strain along with the native culture was utilized for the optimization of other parameters at 23 liter fermenter (15 liter working volume). At the large scale fermentation unit and investigating various fermentation parameters, such as carbon sources and their concentrations, nitrogen sources, air flow.