Identification and characterization of a novel bacteriocin PCM7-4 and its antimicrobial activity against Listeria monocytogenes

Listeria monocytogenes, a pathogenic bacterium causing zoonotic diseases, necessitates the urgent search for novel anti-Listeria monocytogenes drugs due to the continuous emergence of drug-resistant bacteria. In this study, we isolated and identified a bacteriocin-producing strain CM7-4 from seawater as Bacillus velezensis through 16S rRNA sequence analysis. Moreover, we successfully purified a novel bacteriocin named PCM7-4 from Bacillus velezensis CM7-4. The molecular weight of PCM7-4 was determined to be 40,228.99 Da. Notably, PCM7-4 exhibited broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria with a minimum inhibitory concentration (MIC) of 5.625 μg/mL against Listeria monocytogenes specifically. It demonstrated heat resistance and high stability within the pH range of 2-12 while being sensitive to proteinase K degradation without any observed hemolytic activity. Furthermore, SEM analysis revealed that PCM7-4 effectively inhibited biofilm formation and disrupted cell membranes in Listeria monocytogenes cells. Transcriptome analysis revealed that PCM7-4 exerts an impact on genes associated with crucial metabolic pathways, encompassing the biosynthesis of secondary metabolites, phosphotransferase systems (PTS), and starch/sucrose metabolism. These findings highlight the significant potential of bacteriocin PCM7-4 for the development of effective antimicrobial interventions targeting food-borne pathogenic bacteria.