Effect of Saccharomyces cerevisiae cell-free supernatant on the physiology, quorum sensing, and protein synthesis of lactic acid bacteria.

In the food industry, the competition and reciprocity between lactic acid bacteria (LAB) and yeasts in co-culture and the interactions of their metabolites affect product quality. Quorum sensing (QS) is a communication mechanism between bacterial cells, which participates in multiple physiological behaviors. The effects of Saccharomyces cerevisiae YE4 cell-free supernatant (CFS) on LAB were explored from the aspects of growth and metabolism, QS, and protein expression. The results showed the CFS inhibited not only the growth of Enterococcus faecium 8–3 and Lactobacillus fermentum 2-1 but also their acid production and biofilm formation. The acid production and biofilm amount was significantly decreased by 18.4% and 12.8% in L. fermentum 2–1 and E. faecium 8–3, respectively. The effect of CFS on QS was shown in the changes of Autoinducer-2 (AI-2) activity, luxS and pfs genes expression. Moreover, a total of 136 proteins of E. faecium 8-3 differed significantly in co-cultured with CFS, which involved in metabolic pathways including oxidative phosphorylation, pyruvate metabolism, metabolic pathways, mismatch repair, QS system, two-component system, and ABC transporters. Therefore, S. cerevisiae YE4 CFS might affect the physiological metabolism of E. faecium 8-3 by affecting the energy metabolism and QS system. • S. cerevisiae YE4 CFS influenced E. faecium and L. fermentum physiological behaviors. • S. cerevisiae YE4 CFS caused changes in AI-2 activity and QS gene expression. • YE4 CFS might achieve inhibition by affecting energy metabolism and QS system. [ABSTRACT FROM AUTHOR]