Abstract:Yeast and lactic acid bacteria are two kinds of important fermentative microorganisms in liquor production and their interactions that have significant impact on the production and quality of liquor. The effects of the interactions of Saccharomyces cerevisiae MY-15, producing high levels of ester, and three common lactic acid bacteria (Lactobacillus casei lca, Pediococcus pentosaceus L1, and Bacillus coagulans NJ) in liquor production on the growth and metabolism were analyzed in this study. The results demonstrated that lactic acid bacteria significantly inhibited the growth and ethyl acetate-production of S. cerevisiae MY-15, and had marginal impact on the liquor production. However, lactic acid, the metabolite produced by lactic acid bacteria, had a remarkable inhibitory effect on the growth and metabolism of S. cerevisiae. S. cerevisiae, producing high-yield ester could significantly inhibit the growth of L. casei lca; however, in small amounts it stimulated the growth of P. pentosaceus L1 and B. coagulans NJ. With increasing amounts of inoculated S. cerevisiae cells, the amount of lactic acid produced as a result of the metabolism of lactic acid bacteria showed a downward trend after an initial increase. The inhibitory effect of ethanol on the growth and metabolism of lactic acid bacteria was not significant when the content of ethanol was less than 7.5% (V/V). However, when the content of ethanol was increased to 17.5% (V/V), the growth of lactic acid bacteria was completely suppressed.
