The ability of 13 strains of multi-stress-tolerant Issatchenkia orientalis yeast to produce ethanol was examined under different stress conditions, including conditions of elevated H2SO4 and Na2SO4 concentrations and increased heat. The MF-121 strain produced a significant amount of ethanol after the incubation in acidic media containing high concentrations of salt, e.g., 50 g/l Na2SO4 at pH 2.0, or at high temperatures, e.g., 43 degrees C, when compared with other strains. (C) 2011, The Society for Biotechnology, Japan. All rights reserved.