Screening Useful Isolated Yeasts for Ethanol Fermentation at High Temperature
Dung, Ngo Thi Phuong; Pornthap Thanonkeo; Huynh Xuan Phong

Abstract
Due to a current challenge of increasing global temperature, thermo-ethanologenic yeasts receive considerably interest nowadays. In this study, 11 of 31 yeast isolates selected from the previous research based on their well growth at temperature up to 45°C were tested for fermentative capacity and ethanol tolerance at high temperatures. Five isolates BM2, BM3, HX1, C2 and V2 performed significantly well (at the 95% confidence level) in fermentation at 40°C. Of which BM3, BM2, HX1 and C2 were able to tolerate up to 15% v/v ethanol. After 5 days of fermentation at high temperature (40oC), the highest fermentation yield of yeasts could reach up to 76% and this was found in fermentation from saccharified glutinous rice liquid, indicating the further application feasibility of these yeasts for ethanol production at high temperature. Four selected target yeasts were characterized as follow: HX1: Candida tropicalis, BM3: Torulaspora globosa, both C2 and BM2: Pichia kudriavzevii.

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