Acetate Secretion Induces Bacteriocin Synthesis and Activates the Transcriptional Regulators rgg and rpoD

Abstract

Bacteriocins from lactic acid bacteria are natural preservatives that inhibit foodborne pathogenic microorganisms. Co-culture is a form of population competition to induce bacteriocin production. In this study, we aimed to investigate the regulatory response of Lactaseibacillus paracasei HD1.7 to population competition and examine acetic stress during bacteriocin production. The cell-free supernatant of Bacillus subtilis positively and negatively regulated L. paracasei HD1.7 bacteriocin production, which depended on the growth period of B. subtilis ATCC 11774 and the addition ratio of the cell-free supernatant. We found that L. paracasei HD1.7 sensed B. subtilis ATCC 11774 through the cell-free supernatant, and then, acetic acid was secreted to promote bacteriocin production. There was a close connection between acetic acid metabolism and the bacteriocin regulatory system. In addition, transcriptomic analysis revealed that the functions of the transcriptional regulators rgg and rpoD in the bacteriocin regulatory system were enhanced with increasing acetic acid stress concentration. Collectively, the results of this study increase our current understanding of L. paracasei HD1.7 bacteriocin production and provide insights into high bacteriocin production by co-culture or acetic acid induction.