The thermotolerant yeast was isolated from silage produced at Suranee
University of Technology farm. The cell morphology of the yeast cells under
microscope is ovoidal to elongate, single or in pairs. Budding cells are present and
pseudomycelia are developed. Based on biochemical characterisics from API
Candida strip, the thermotolerant yeast strain S1 was identified as Candida krusei.
Moreover, from the results of the comparision of PCR-amplified 18S rDNA sequence
the thermotolerant yeast strain S1 was closely related to Issatchenkia sp. The S1
strain did not produce killer toxin when tested with S. cerevisiae EC 1118, E. coli
ATCC 25922 and B. subtilis ATCC 6633, and it was able to tolerate ethanol in YPD
medium containing ethanol up to 25% (v/v), the growth was highest in 5% (v/v)
ethanol