Fermentation yeast strain was tried to isolate from a traditional Vietnamses starter called men used in the local microdistillery at Cai Lay district in Vietnam using plates of an agar-solidified YPD medium (yeast extract, 10 g; peptone, 20g; glucose, 20 g; tap water, 1.000 mL) containing 50 ug chloramphenicol/mL. The isolated strain of yeast was maintained on YPD slopes.

A strain of yeast designated Y3 was isolated from the Vietnamese men. Y3 yeast was found to be fermentation yeast with globose or subglobose cells. Pseudohyphae were not observed during cultivation. D-Glucose, D-galactose, mannose, maltose, and sucrose were fermented, while lactose was not. rDNA analysis of Y3 yeast was carried out and was identified as a strain of Saccharomyces cerevisiae.

Fermentation test was done using the 3 yeast strains, S. cerevisiae Y3, S. cerevisiae NP01 isolated from Thai microbial starter loog pang, and industrial sake brewing yeast K7. Ethanol fermentation with cooking anh without cooking was done according the general procedure using 30 g of unpolished nonglutious rice grains and 0.2 of Sumizymes as the saccharifying agent. Total amount of deionized water was 100 mL including a portion of yeast suspension, which readily brought the population of yeast in the initial mash to 3.0 x x10⁷ cells/mL in the 300 mL Erlenmeyer flask. Ethanol fermentation was conducted at 25^oC in the dark.

Fermentaion of the mash completed around 5 days. The ethanol concentration of rice wines were around 12.0 to 14.5% (v/v). Y3 and NP01 yeast were isolated from the starter of tropical or su-tropical area and it was considered that fermentation has advanced quickly in warm environment of 25^oC.