Abstract

The strain, Lactobacillus plantarum F12 with probiotic traits was isolated from Algerian healthy children faeces and identified by 16S rDNA sequencing. In this study, the antimicrobial activity and physicochemical properties of bacteriocin-like substance (BLS) produced by this strain were determined. Also, the bacteriocinogenic genes of plantaricin A, plantaricin J and plantaricin K were screened in this strain. The BLS inhibited a range of pathogenic and spoilage bacteria including Escherichia coli, Salmonella infantis, Salmonella typhimurium, Shigella sonnei, Staphylococcus aureus, Listeria monocytogenes, Listeria innocua, Bacillus subtilis and some lactobacilli sp. The BLS was proteinaceous since it was inactivated by the proteolytic enzymes (trypsin, proteinase K and pronase) but not by α-amylase and lipase. It was heat stable at different temperatures (40 - 121°C) for 30 min and retained its activity at a wide range of pH values (2 to 10). Its activity was totally preserved at -80°C for 120 days and at -20°C for 60 days. The amplification of genetic determinants of plnA, plnJ and plnK has shown the presence of these genes in L. plantarum F12. The ability of the BLS from L. plantarum F12 to inhibit several pathogenic/spoilage bacteria and its characterization demonstrated its interest as a natural food preservative, in addition to its probiotic potential in prevention and treatment of infectious diseases.

Key words: Lactobacillus plantarum, plantaricin J/K, plantaricin A, bacteriocin-like substance, characterization.