Characterization and mode of action of a potent bio-preservative from food-grade Bacillus licheniformis MCC 2016

Abstract

The antibacterial peptide of Bacillus licheniformis MCC 2016 have potential biopreservative efficacy. Here, we report the purification process, properties, and mode of action of this antibacterial peptide for its potential application in the food industry. The antibacterial peptide from the cell-free supernatant was purified using a sequence of purification steps. The purified antibacterial peptide showed a specific activity of 68817 AU mg⁻¹ and 0.4% yield. Liquid chromatography-mass spectroscopy analysis showed an mz⁻¹ value of 279.28 for the active peptide. The SDS-PAGE analysis confirmed the antibacterial peptide is low-molecular weight and the size is between 3.0 and 3.5 kDa. Scanning electron microscopy, Fourier transform infrared spectroscopy, β-gal induction assay and release of UV-absorbing materials indicated that the antibacterial peptide targets the cell wall of pathogens. Minimum inhibitory concentration of the antibacterial peptide against Listeria monocytogenes Scott A and others (Kocuria rhizophila ATCC 9341, Staphylococcus aureus FRI 722 and Salmonella typhimurium MTCC 1251) was found to be 1600 and 800 AU mL⁻¹, respectively. The antibacterial peptide is temperature and pH stable, proteolytic-enzyme-sensitive, low-molecular weight, cell wall active class I bacteriocin and exhibits remarkable antibacterial activity against pathogens, suggesting its application as a potential biopreservative in the food industry.

Keywords:

• Antibacterial peptides
• Bacillus licheniformis
• biopreservation
• foodborne pathogens
• mode of action

Acknowledgments

The authors wish to acknowledge The Director, CFTRI, Mysore for providing the facilities. NV acknowledges CSIR for the fellowship. Authors thank Professor Thorsten Mascher Technical University of Dresden, Germany for kindly providing the reporter strains. Work was carried out under the institute project MLP83.