Antagonistic interaction between yeasts and lactic acid bacteria of oenological relevance. Partial characterization of inhibitory compounds produced by yeasts

Abstract

The interactions between wine yeasts and wine lactic acid bacteria were evaluated. The double-layer plate-growth method showed bacterial inhibition by yeasts as the most common interaction, being Oenococcus oeni more sensitive than Lactobacillus hilgardii. During sequential inoculations in the media fermented by Saccharomyces cerevisiae mc2 or Candida pulcherrima 3, showed strongest inhibition by S. cerevisiae. The inhibitory effect exerted by S. cerevisiae mc2 on O. oeni X2L and L. hilgardii 5w growth could be due to a synergistic effect between fermentation metabolites and another compound(s) with a molecular size of 3-10kDa. The last compound(s) was partially sensitive to protease and heat treatments, suggesting a peptidic nature structure. Although this yeast inhibited O. oeni growth, did not affect the malolactic activity. The peptidic inhibitory compound(s), heat and protease sensitive, showed a molecular weight between 3 and 10kDa. Flow cytometry revealed different physiological responses of O. oeni and L. hilgardii to peptidic fraction. C. pulcherrima would exert its inhibitory effect on bacteria through low molecular weight metabolites.