Isolation and characterization of high stress tolerance yeast from various sources in Bangladesh

Abstract

Bioethanol is becoming popular day by day because of its increasing demand as a renewable resource. A single celled eukaryotic living organism called yeast plays a vital role in producing alcohol. Though there are many organisms can interfere the process like acetobacter. However, it is almost impossible for other organism to compete with yeast due to its instinct. In addition, yeast releases alcohol as a byproduct which has strong antimicrobial activity. Thus, yeast is dominant in its environment since most of the microorganisms cannot tolerate alcohol. on the contrary, increasing amount of alcohol can also inhibit the growth of yeast and put the organism in stationary phase. The aim of this study is to isolate and characterize a yeast which can tolerate high concentration of alcohol as well as stress and can produce more alcohol before reaching the stationary phase. For this purpose, primary sample has been collected from Lavender flower, Apple skin, Grape skin, honey and yeast from stressed environment created manually. In thermo tolerance test, isolated yeast sample showed significant growth at 27˚C and 30˚C. on the other hand, it showed high osmo tolerance in addition of NaCl in different concentration. Lastly, it showed significant growth in 5% and 10% ethanol concentration. Since it showed a significant tolerance in the tests, it could be a promising strain to use in future for industrial purpose.