Penicillin Binding Protein from Pediococcus acidilactici Isolated from Nuruk for Food Biopreservative

Background: Korean traditional nuruk, consisting of a variety of microorganisms, is widely used in traditional liquor materials. The present study evaluated the antimicrobial activity of strains isolated from Korean traditional nuruk in 2016. Methods: The strain was isolated from Korea traditional nuruk and performed antimicrobial activities using the paper disc test and phylogenetic analysis using 16S rRNA sequencing. The bacteriocin was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Results: The isolate, S-2, demonstrated highest antibacterial activity against various gram-positive and gram-negative pathogens, including Klebsiella pneumoniae, Salmonella enterica subsp. enterica, Bacillus subtilis, B. cereus, Escherichia coli and Shigella flexneri. The isolated was identified as P. acidilactici, by 16S rRNA sequence analysis. Antibacterial activity of P. acidilactici was retained over a wide temperature range. And the P. acidilactici strains remained active over a wide pH range. However, reduced activities were obtained at alkaline pH. When the bacteriocins from this strain were treated with proteolytic enzymes, loss of antibacterial activity was observed. No effect in the activity, however, was observed upon treatment with alpha-amylase, beta-amylase, lipases, proteases, and proteinase K. The molecular weight of bacteriocins was estimated to be approximately 51 kDa. Using MALDI-TOF/MS, the bacteriocins were identified as a putative penicillin binding protein. Conclusion: This study is the first report of isolation of bacteriocin with the above mode of actions from Korean traditional nuruk. The bacteriocins produced by the strain have potential applications in food preservation.