Bacterial contamination causes yield reduction during ethanol production from molasses. To prevent contamination, construction of a fermentation system using acetate-tolerant yeast under an acetate-containing condition was attempted. Schizosaccharomyces pombe was screened as an acetate-tolerant strain. Bacterial contamination was significantly prevented by the combined use of Sc. pombe and acetate. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.