isolation of high ethanol resistant strains of saccharomyces cerevisiae

several strains of saccharomyces cerevisiae were isolated from different sources. these strains were under taken for ethanol tolerance analysis and growth under stress condition. exponential phase to various concentrations of ethanol (2–26% v/v) for 1 h was used for isolation of resistant strains. viable cells were isolated and purified by inoculation of diluted samples on yeast extract peptone agar medium at 30 ºc for 24 h. all resistant strains were grown on solid aerobic low peptone medium supplemented with 24% (v/v) ethanol but had variations at growth intensity in this condition. invertase enzyme activity in yeast isolates was measured and comparing with control samples resistant strains did not show significant difference in the enzyme activity. as resistant strains to ethanol have different content of fatty acids in cell membrane and resistance mechanisms, they can be used in various fields of biotechnology such as ethanol production, recombinant-protein expression, trehalose production and novel drug development.