Identification and characterization of a novel bacteriocin PFB252 from Bacillus velezensis with anti-MRSA and anti-biofilm activity for dairy food preservations.

Abstract

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) and its robust biofilm-forming capability pose severe threats to public health, livestock production, and food safety, and undersocres the urgent need for novel antibacterial and anti-biofilm agents. In this study, we identified and characterized a novel bacteriocin, PFB252, derived from Bacillus velezensis through a multi-step purification process involving acid precipitation, TA-GF75 gel column chromatography, Tiderose Q HP anion-exchange chromatography, and RP-HPLC. PFB252 exhibited remarkable thermal stability, pH tolerance, and resistance to enzymatic degradation, and demonstrated potent antibacterial activity against MRSA. At sub-inhibitory concentrations (1/32 × MIC and 1/16 × MIC), PFB252 significantly disrupted biofilm formation and impaired the metabolic viability of embedded bacteria, while drastically reduced extracellular polysaccharide, the key component of the biofilm matrix. Transcriptional analysis further revealed that PFB252 at sub-inhibitory concentrations downregulated critical biofilm-associated genes. PFB252 exhibited strong antimicrobial efficacy in dairy applications. It could reduce MRSA counts in milk from 10³ to < 10 cfu/mL within 4 d at MIC and maintaining suppression in cheese below 10² cfu/g over 7 d. These properties highlight PFB252's potential as a natural bio-preservative for combating MRSA in food systems and offer a promising solution for food safety applications.