Screening of Stress Tolerant Yeast and Temperature Variable for Ethanol used Sugarcane Juice as a Carbon Source

Abstract

solation of thermotolerant yeast strain from sugarcane bagasses in sugar factory was carried out  in Yeast extract-Peptone-Dextrose (YPD) medium with ethanol 4% (v/v) and incubation at 37 o C. Ninety-eight thermotolerant yeast isolates were screened that are able to produce ethanol from gases generated in
liquid yeast indicate that 23 isolates gas generated from 4.0-5.0 cm in a Durham tube. Study of osmotolerant and thermotolerant showed that selected yeast isolates grow well at temperatures of 37- 45^o C, with some isolates can grow well at a temperature of 47^o C include BRMU02, BRMU03, BRMU04, BRMU06. , BRMU08, BRMU12, BRMU17, BRMU19, BRMU29 and BRMU30 but all selected yeast isolates were unable to grow at a temperature of 50^oC. Osmotolerant results exhibited all isolates can grow well at
glucose concentration 30% (w/v) and nine isolates that grow well at xylose concentration 20% (w/v). Ethanol in synthesis medium at 37 ^oC that was produced from BRMU29, BRMU19 and BRMU08 were 7.28, 7.05 and 6.89 (%, v/v) , respectively. Variable of high temperature for ethanol production in sugarcane juice fermentation medium, including 37, 40 and 45 °c showed that BRMU29 can produced the highest ethanol were 3.76, 3.64 and 3.68% (w/v) at 36, 48 and 60 hours, respectively. The research revealed that three yeast isolates are interesting in applying to a starter culture for the production of ethanol because it can grow well and produced ethanol at high temperatures. They also have the ability to tolerate high concentrations of sugar to reduced the contamination of other microbes during fermentation