In vitro evaluation of antimicrobial activity of Lactic Acid Bacteria (LAB) isolated from Buffalo milk against most common pathogenic and spoilage food bacteria

ABSTRACT Growing consumer demand for preservative-free foods has increased interest in natural antimicrobials as alternatives to synthetic preservatives. Lactic acid bacteria (LAB) with antimicrobial properties represent a promising resource for the food industry, with buffalo milk emerging as a valuable source. In this study, one hundred strains, identified using MALDI-TOF-MS, were assessed for antibiotic susceptibility and haemolytic activity. Cell-free supernatants (CFS) were tested against major foodborne pathogens using the agar-well diffusion method, showing antimicrobial activity against all targets, with Listeria monocytogenes being the most sensitive. Proteinase K treatment and pH neutralization suggested the possible presence of bacteriocin-like compounds in four CFS, confirmed by genome sequencing of Lactiplantibacillus plantarum LC44 (Pediocin_PA and a bacteriocin immunity protein). The strain lacked transferable antibiotic resistance genes and haemolytic activity. Findings highlight that LAB from buffalo milk may represent promising candidates as natural bio-preservatives, with potential applications in improving food safety and extending shelf life.