In vitro characterization of a vancomycin-resistant strain of Leuconostoc lactis isolated from chicken carcasses and its activity against some foodborne pathogens

Recently, increasing attention has been paid onLeuconostoc lactis as a promising bioactive organism against food-borne and spoilage bacteria.A total of nine strains, including six different species of the genus Lactobacillus and three species of the genus Leuconostoc, were isolated from chicken carcasses (n=60) collected from wholesale poultry markets located at Al-Riyadh city, Saudi Arabia in 2016 and identified by API 50 CHL assays.L. lactis isolates were resistant to bile salts and vancomycin.The autolytic phenotype of L. lactis was evaluated under starvation conditions in the presence of potassium phosphate buffer.The strains tested showed partial autolysis of approximately 18% after 7 h of starvation at 37°C at the end of the exponential phase.The inhibitory activity of whole-protein extracts of L. lactis against the foodborne bacteria, Listeria monocytogenes, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Micrococcus luteus was evaluated by renaturing sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE).The major activity of the total protein appeared as two clear bands on the SDS-PAGE, of approximately 57 and 42 kDa against L. monocytogenes, B. cereus and B. subtilis.No active band was shown against S. aureus and M. luteus.