The potential mechanism and key genes of bacteriocin production in Lactiplantibacillus plantarum ZY-1 induced by co-cultivation with Limosilactobacillus fermentum RC4

The bacteriocin of lactic acid bacteria (LAB) can be effectively enhanced by co-cultivation with other strains. However, the mechanisms beyond classical quorum sensing (QS) molecules remain to be elucidated. Herein, we co-cultured Limosilactobacillus fermentum (L. fermentum) RC4 with the bacteriocin-producing Lactiplantibacillus plantarum (L. plantarum) ZY-1, and observed a significant increase in bacteriocin yield by ZY-1. To study how co-cultivation induces bacteriocin production in LAB, we performed whole-genome sequencing of ZY-1 and analyzed the transcriptomics of monoculture and co-cultivation to identify differentially expressed genes (DEGs), then overexpressed these DEGs (pflA, pnuC, ttdB) to verify their roles in regulating bacteriocin production during co-cultivation. The results indicated that four gene clusters associated with secondary metabolite synthesis were present in ZY-1, and six types of core peptides were identified in the metabolites. Bacteriocin production reached its peak 24 h post co-cultivation. Co-cultivation significantly enhanced carbohydrate metabolism, stimulated membrane transport processes, and regulated both amino acid and nucleic acid metabolism, leading to an increase in bacteriocin production. Overexpression of three DEGs significantly boosted bacteriocin yields, with ttdB increasing by 18 %, highlighting their key roles in bacteriocin induction during co-cultivation. These three genes were first reported to enhance bacteriocin production in co-cultivation.