Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jln. Raya Bandung-Sumedang km. 21 Jatinangor, Sumedang, West                                                          Java, 45363, Indonesia

School of Agricultural, Computational and Environmental Sciences, Faculty of Health, Engineering and Sciences, University of Southern Queensland, West St., Toowoomba, Queensland, 4350, Australia

The present study investigates yeast membrane fluidity and ethanol tolerance, particularly in relation to inositol supplementation. Three Saccharomyces cerevisiae strains were selected, based on reported stress tolerance and ethanol productivity; an ethanol tolerant baker’s yeast (A12), a wine yeast (PDM) and a sake yeast (K7), the latter two producing up to 17 and 17.5 %(v/v) ethanol, respectively. When cultured in yeast nitrogen base (YNB) medium with 2% (w/v) glucose, the three strains had similar growth rates and performance, although K7 maintained significantly higher viability. Comparison of generalized polarization (GP) of laurdan-labelled cells indicated that PDM had the highest membrane fluidity, followed in order by K7 and A12. Conversely, A12 had the highest ethanol tolerance, followed in order by K7 and PDM. Furthermore, in comparison to 6 h cultures, 24 h cultures of all strains had lower membrane fluidity and higher ethanol tolerance. The present study failed to confirm reports that inositol supplementation increases ethanol tolerance. No significant changes of either GP or viability reduction upon ethanol stress were found when the medium was supplemented with various levels of inositol. Further investigation, including more variations in concentration and zero level of inositol, is needed to elucidate this possibility.