BACTERIOCINOGENIC LACTIC ACID BACTERIA ISOLATED FROM DIFFERENT LOCAL SOURCES IN UZBEKISTAN AND THEIR ANTIMICROBIAL ACTIVITY
Miralimova S., Ogay D., Kutlieva G., Sokhibnazarova K., Elova N.
Institute of microbiology of AS of Uzbekistan, Uzbekistan
Antimicrobial resistance of microorganisms become a global problem and without urgent, coordinated action, the world is heading towards a post-antibiotic era, in which common infections and minor injuries, which have been treatable for decades, can once again kill. This stipuates necessity to search for new infection treatment options and other tools (WHO, 2015). Bacteriocins of lactic acid bacteria have a great potential for application as preservatives in food industry and as alternative to antibiotics in medicine (Arques J. et al., 2015).
The aim of this work was to screen for bacteriocin-producing lactic acid bacteria among the strains isolated from a range of traditional fermented products, to study their spectrum of antimicrobial activity and their probiotic properties such as acid-, bile- and salt-tolerance, susceptibility to antibiotics.
Forty two strains of lactic acid bacteria were isolated from the kumis (fermented horse milk), shubat (fermented camel milk), sauerkraut and screened for antagonistic activity, 31 of them showed antagonistic activity against several gastrointestinal disorder agents and foodborne pathogens, such as Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Candida albicans, Pseudomonas aeruginosa, Proteus morganii, Citrobacter freundii, Serratia marcescens, Staphylococcus aureus, Helicobacter pylori. Based on the loss of antimicrobial activity after treatment with proteinase K and pepsin (Klaenhammer T. et al., 2012) the proteinaceous nature of antimicrobial substances of 6 isolates have been established. Identification of the isolates producing bacteriocins have been performed based on carbohydrate fermentation pattern and 16S rRNA gene sequence.
According to phenotypic and genotypic identification 2 isolates are Lactobacillus plantarum, one is Lactobacillus rhamnosus and the remaining Lactobacillus isolates are not identified to species yet. Among these strains, L. plantarum 42 produce a bacteriocin which inhibits the growth of E. faecalis and E. faecium strains, L. plantarum 44 produces a bacteriocin against P. morganii strain, L. rhamnosus bacteriocin inhibits the growth of H. pylori strains and other isolates have protease eliminated inhibition against E. coli, P. aeruginosa, S. marcescens, P. morganii, S. aureus strains.
All identified Lactobacilli were found to be resistant to bile salts (0.6%), NaCl (8%) and pH 3, susceptible to most antibiotics.
Several conditionally-pathogenic bacteria appear to be sensitive to bacteriocins produced by the isolates: E. faecalis and E. faecium, which are cause gastrointestinal infections; P. morganii - urinary tract infections; H. pylori – gastric and duodenal ulcer agent; S. marcescens - urinary tract infections, sepsis and pneumonia; P. aeruginosa, E. coli and S. aureus infections can involve any part of the body and the latter two bacteria are identified as a food-borne pathogens. Taking into account the clinical importance of susceptible strains, tolerance to bile, salts and low pH these Lactobacillus isolates have a great potential for application in pharmaceutical and food industry as a bio therapeutic agents and probiotic products.
Keywords: Lactic acid bacteria, Bacteriocins, Antimicrobial activity, Probiotics, Food-borne pathogens
Miralimova S., et al. (2016). Bacteriocinogenic lactic acid bacteria isolated from different local sources in Uzbekistan and their antimicrobial activity.
Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 48.). IPC2016