Yeast population dynamics of industrial fuel-ethanol fermentation process assessed by PCR-fingerprinting

Yeast populations used in industrial production of fuel-ethanol may vary according to the plant process conditions and to the environmental stresses imposed on yeast cells. Therefore, yeast strains isolated from a particular industrial process may be adapted to such conditions and should be used as the starter strain instead of less adapted commercial strains. This work reports the use of a PCR-fingerprinting method based on microsatellite primer (GTG)₅ to characterize the yeast population dynamics during the fermentation period in six distilleries. The results show that indigenous fermenting strains present in the crude substrate can be more adapted to the industrial process than commercial strains. We also identified new strains that dominated the yeast population and were more commonly present either in molasses or sugar cane fermenting distilleries. Those strains were proposed to be used as starters in those industrial processes. This is the first report on the use of molecular markers to discriminate Saccharomyces cerevisiae strains from the fuel-ethanol producing process.