DISSERTATIONSubmitted to the Punjab Agricultural University, Ludhiana, in partial fulfillment of the requirements for the degree ofDOCTOR OF PHILOSOPHY IN MICROBIOLOGY. Year 1995.ABSTRACTEight strains of yeasts, namely S. cerevisiae-220, S. cerevisiae-360, S. cerevisiae-181/3c, Trichosporon beigelli, Candida haemulonii, C. parapsilosis, Candida sp.-3(1) and Candida sp.-5(2) have been evaluated for their potential to ferment cane sugars to ethanol at three temperatures. S. cerevisiae-220 utilized 84.0% substrate in 60 h at 30 ± 1 °C. S. cerevisiae-360 fermented substrate more efficiently (69.3%) at 38 ± 1 °C. S. cerevisiae-220 multiply faster at 30 ± 1 as well as at 38 ± 1 °C.S. cerevisiae-220 could withstand 13.0% ethanol whereas S. cerevisiae-360 tolerated only 8.0% of ethanol supplemented in the growth medium. The protoplasts of S. cerevisiae-220 and S. cerevisiae-360 fused together could not generate ethanol more efficiently than their parents at 38 ± 1 °C. S. cerevisiae-220 adapted at 38 ± 1 °C utilized 64.4% of substrate during 60 h.Wine with commercially outstanding quality has been prepared from Zingiber officianale with S. cerevisiae-220-A at 38 ± 1 °C.