Characterization, Cytotoxic Analysis and Action Mechanism of Antilisterial Bacteriocin Produced by Lactobacillus plantarum Isolated from Cheddar Cheese

Emergence of food borne pathogens and multidrug resistant organisms has enforced the screening of natural antimicrobial compounds. Bacteriocins are ribosomally synthesized natural antimicrobial peptides produced by numerous bacteria. These antimicrobial peptides are gaining more attention as alternative therapeutics in pharmaceutical industry as next-generation antibiotics targeting the multi-drug resistant pathogens and as a bio preservative in food industry. The current study is aimed to purify and characterize a broad spectrum bacteriocin (Bac-IB45) with the determination of its plausible mode/mechanism of action. In this research, Bac-IB45 from Lactobacillus plantarum KIBGE-IB45 was 41.71-fold purified with the molecular mass of 20.5 kDa estimated using tricine SDS-PAGE. This bacteriocin is highly thermostable and pH stable in nature. It also exhibited stability against various metal ions, surfactants and organic solvents. Purified Bac-IB45 showed broad antimicrobial potential against various multidrug resistant, food borne bacterial and fungal pathogens. However, Bac-IB45 was found to be sensitive to various proteolytic enzymes. The time-kill assay of Bac-IB45 and scanning electron microscopic analysis revealed the bactericidal mode/mechanism of action against Listeria monocytogenes ATCC 7644. This unique Bac-IB45 with broad spectrum of inhibition and bactericidal mode of action could be used as a natural food preservative and as alternative therapeutics to solve the unrestrained problems of industries.