Abstract
Recently, increasing attention has been paid on Leuconostoc 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. Key words: Bacteriocins, biopreservation, lactic acid bacteria, pathogens, poultry.
Highlights
Leuconostoc is a genus of Gram-positive bacteria, placed within the family of Leuconostocaceae
According to the API 50 CHL assays, these isolates belonged to five different species of the genus Lactobacillus and one isolate belonged to the genus, Leuconostoc
The percentage of each species identified, out of the total number of species examined, varied as follows: L. lactis presented the highest ratio (33.33%), followed by Lactobacillus salivarius (22.22%), and the lowest ratios were obtained for Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus fermentum and Lactobacillus brevis
Summary
Leuconostoc is a genus of Gram-positive bacteria, placed within the family of Leuconostocaceae. They are generally ovoid cocci often forming chains. Some species of the genus are capable of causing infections in humans (Coovadia et al, 1987; Coovadia et al, 1988), Leuconostoc may be used to improve food hygiene, safety and shelf-life by producing antimicrobial substances such as bacteriocins, lactic acid and hydrogen peroxidase (Holzapfel et al, 1995; Jay 1996). Some lactic acid bacteria, including those belonging to the groups Lactobacillus, Streptococcus, Pediococcus and Leuconostoc, have been reported to possess active probiotic capabilities (Fuller, 1991; Ogunshe 2008)
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