S. cerevisiae TISTR 5048 and E. aerogenes TISTR 1468 were obtained from Thailand Institute of Scientific and Technology Research (TISTR), Thailand. The culture of S. cerevisiae was maintained on MPDY (malt extract 0.3%, peptone 0.5%, yeast extract 0.3% and dextrose 2%) agar (1.5%) slant at 4oC [1]. E. aerogenes was cultivated on Luria-Bertani (LB) agar.