Combined transcriptomics and metabolomics analysis reveals the antifungal activity and mechanism of Enterococcus faecium cell-free supernatant against Alternaria alternata

Certain lactic acid bacteria have been utilized as bacteriostatic agents in the context of fruit and vegetable spoilage fungi. Although Enterococcus faecium is a member of the lactic acid bacteria group, its application in the prevention of post-harvest fruit spoilage remains largely unexplored. We investigated the activity of E. faecium cell-free supernatant (CFS) against fruit and vegetable spoilage fungi and probed the possible fungistatic mechanisms involved. The in vitro results showed that CFS possessed significant antifungal activity against Alternaria alternata with a MIC of 20%, which resulted in distorted rupture of A. alternata cell membranes and leakage of cellular components in a dose-dependent manner. In addition, transcriptomics and metabolomics results showed that CFS could also inhibit the growth of A. alternata by altering energy metabolism, impairing intracellular antioxidant function, reducing intracellular hormone biosynthesis, and slowing down or stopping asymmetric cell division. In summary, E. faecium CFS has been shown to effectively inhibit A. alternata.