Isolation and Phylogenetic Analysis of Two Thermotolerant, Fermentative Yeast Strains from Liquid Tape Ketan (Indonesian Rice Wine)

摘要

A total of 34 yeast strains were isolated from rice wines pressed from tape ketan, Indonesian traditional fermented-glutinous rice. Among them, two strains that grew and fermented above 42℃ were selected for further analysis. Fermentation was carried out in medium containing 15% (w/v) glucose at 40℃, and ethanol productivity was measured after 48 h of incubation. The two strains, TB2-1 and TW1-3, were found to have upper temperature limit of 46 and 47℃, and higher ethanol productivity of 5.9% and 6.4% (w/v), respectively. These two yeast strains were identified by traditional and molecular techniques. In the molecular technique, 18S rDNA and internal transcribed spacer 1 (ITS1) rDNA genes were amplified by polymerase chain reaction (PCR) using specific primers. The sequences of these two regions for the two strains were phylogenetically analyzed, and the yeast strains TB2-1 and TW1-3 were identified as Issatch-enkia orientalis and Saccharomyces cerevisiae, respectively.