Physiology, quorum sensing, and proteomics of lactic acid bacteria were affected by Saccharomyces cerevisiae YE4.

The interaction mode between lactic acid bacteria (LAB) and yeast in a fermentation system directly determines the quality of the products, thus understanding their mode of interaction can improve product quality. The present study investigated the effects of Saccharomyces cerevisiae YE4 on LAB from the perspectives of physiology, quorum sensing (QS), and proteomics. The presence of S. cerevisiae YE4 slowed down the growth of Enterococcus faecium 8-3 but had no significant effect on acid production or biofilm formation. S. cerevisiae YE4 significantly reduced the activity of autoinducer-2 at 19 h in E. faecium 8-3 and at 7-13 h in Lactobacillus fermentum 2-1. Expression of the QS-related genes luxS and pfs was also inhibited at 7 h. Moreover, a total of 107 E. faecium 8-3 proteins differed significantly in coculture with S. cerevisiae YE4-these proteins are involved in metabolic pathways including biosynthesis of secondary metabolites; biosynthesis of amino acids; alanine, aspartate, and glutamate metabolism; fatty acid metabolism; and fatty acid biosynthesis. Among them, proteins involved in cell adhesion, cell wall formation, two-component systems, and ABC transporters were detected. Therefore, S. cerevisiae YE4 might affect the physiological metabolism of E. faecium 8-3 by affecting cell adhesion, cell wall formation, and cell-cell interactions.