1. Science and Research Branch ,Islamic Azad University(SRBIAU) , Tehran 2. Razi Vaccine and serum Research Institute -Agriculture research . Education and Extension organization,Karaj, Iran
Abstract
Introduction
a number of lactic acid bacteria (lab) produce bacteriocin which are bioactive peptides active against a number of pathogenic bacteria. application of lactic acid bacteria (lab) and their bacteriocins are not only considered as natural and safe strategies for controlling this disease in cheese and meat products but have recently gained a lot of attention for their anticancer effects. in this study we isolated and identified bacteriocin producing ability of locally isolated l.casei strains in invitro conditions for possible application as an anticancer agent in future
Methods
eighteen l.casei strains isolated from dairy products and fermented cereals were identified by biochemical and 16srrna sequencing. the antimicrobial activity of the isolates was evaluated against a number of pathogens by agar well diffusion assay. the supernatant fluids of the mentioned strains were evaluated under the stress conditions including neutralization of ph, effect of proteolytic enzymes, and different temperature. supernatant fluids from three of the strains with potential ability to produce bacteriocin like substance (blis) were partially purified by vacuum concentrations, ammonium sulphate precipitation and ion exchange (deae cellulose) chromatography and freeze dried. the anti-proliferative activities of live cells (probiotics) ,heat-killed cells (paraprobiotic) ,cell – free supernatants (postbiotics) and partially purified bacteriocins fractions were tested for their cytotoxicity on mrc5 cell lines while their anticancer effect was evaluated on ht29 and caco2 cell lines using mtt assay.
Results
among the selected 18 l.casei strains, three strains showed presence of bacteriocins or bacteriocin like substance responsible for antibacterial activity. the partially purified fractions from the producer strain and the producer culture (live and dead cells) did not show any cytotoxic effect on mrc5 cell lines. different level of anticancer effects of the samples on the tested colon cancer cell lines was observed.
Conclusion
indigenous l.casei strains appeared potential bacteriocin producers with enhanced antibacterial action against significantly important pathogens and might have potential application as suitable alternatives to antibiotics. additionally the locally isolated l.casei strains and their metabolites mainly bacteriocin harbor anticancer effects and could be exploited in future as a safe biological therapeutic agent for cure of cancer.
