. Isolation and selection of thermotolerant yeast strains Of various techniques to obtain yeasts capable of growing and producing ethanol at high temperature, Banat et al. (1998) stated that isolation from nature was the most successful technique. Therefore, in this work soil samples from natural habitat associated with sugar cane were enriched in sugar cane juice supplemented with 4% (w/v) ethanol and incubated at 35 C. A total of 72 yeast strains were obtained. Among these, 37 strains grew satisfactorily even at 45 C while 18 strains grew only up to 40 C. All of the strains were then subjected to further screening at various high temperature levels. Though Banat et al. (1992) used higher temperatures (45–50 C) for enrichment isolation and obtained several thermophilic yeast strains capable of growth at 52 C and ethanol production at 45–50 C, a lower temperature, 35 C, was used in this study. In order to obtain yeast strains that tolerated both high temperature and ethanol, 4% (w/v) ethanol was added to the medium, for t for the effects of high temperature have been often exacerbated by ethanol concentrations above 3% (Van Uden, 1984).