the ethanol production was decreased within 72 hours. In contrast to aeration for 24
hours, ethanol production was stable with 76.06% theoretical yield. Additionally, the
production of some organic acid using HPLCtechnique was investigated. Amount
40x of unknown compound when compare with acetic acid was detected at the
retension time of 13.5 minutes couple with the growth of yeast and its ethanol
production. Therefore, ethanol production by thermotolerant yeast strain S1 in M9
minimal medium should be considered because this yeast was produced high amount
unknown compound, that might be involved in some metabolisms of this yeast during
ethanol fermentation.