Bactericidal and cell membrane disruption potential of protein extract from buttermilk-derived probiotic Pediococcus pentosaceus OBK05 against Salmonella typhimurium ATCC 14028.

INTRODUCTION: Foodborne Salmonellosis remains a significant global health challenge, and the rise of antimicrobial resistance is limiting the efficacy of traditional antibiotic treatments, emphasising the need to develop natural biopreservatives to improve food safety. The present study evaluates the antimicrobial potential of a bioactive protein fraction isolated from the probiotic isolate Pediococcus pentosaceus OBK05 against the predominant foodborne pathogen, Salmonella typhimurium ATCC 14028. METHODS: Antimicrobial protein was extracted from Pediococcus pentosaceus OBK05 and its inhibitory properties were evaluated through a series of standardised in vitro assays including growth kinetics monitoring and membrane disruptive effects were determined by cell membrane integrity assay and bacterial ultrastructure was determined by Scanning electron microscope. RESULTS: The protein extract showed dose-dependent reduction in pathogen growth with the minimum inhibitory concentration. Growth kinetics and viable cell count revealed a rapid bactericidal effect of the protein extract. The mode of action of the extract involved changes in the membrane structure of pathogen cells, causing metabolic disruption and cellular homeostatic imbalance, as evidenced by the progressive release of intracellular molecules. Furthermore, alterations in cellular structure and function induced by the protein extract were investigated using scanning electron microscopy and analysis of protein expression patterns in treated Salmonella cells. DISCUSSION: Together, these findings demonstrate a multitargeted antimicrobial mechanism of the bioactive protein fraction from Pediococcus pentosaceus OBK05 against Salmonella typhimurium ATCC 14028, establishing its potential as an effective natural biocontrol agent to enhance food safety.