solation and characterization of Lactobacillus strains and evaluation of their antibacterial and cytotoxic activities

Abstract

Probiotics are considered to be living organisms. Which administer some kind of a health effect on their host, when present in a significant amount. Many different genera of bacteria have contributed to probiotics, but Lactic Acid Bacteria (LAB) are of prime importance. studies have shown that probiotic bacteria can restore the gut flora and inhibit pathogens. Currently probiotic role in cancer treatment is also being considered. The aim of the present study was to isolate and characterize LAB strains from local indigenous sources and to evaluate them as potential probiotics. Duck intestines were used as sources for isolation of these bacteria. Identification of bacterial strains was performed by biochemical testing and Ribotyping. Survival, adhesion and colonization were examined in gastrointestinal tract of mice. Antimicrobial activity of isolates against STEC and Shigella was evaluated by well diffusion assay. Cytotoxic activities against cancerous cell lines were evaluated using MTT colometric assay. Results of biochemical testing and riboprinting revealed that isolates belong to Lactobacillus Plantarum. Rifampicin-resistant colonies of these strains were able to be re-isolated from the faeces of mice which were fed these probiotics ensuring their survival. The similar results of colonization were obtained in homogenates of small intestine; large intestine and caecum of mice on the twenty-eight day after feeding with the selected Strains. Results of antibacterial testing showed that each strain of the probiotic bacteria had varying activity against the pathogens under similar conditions. In addition, our findings showed a significant cytotoxic activity against HeLa cell lines. The positive results of the study suggest that these L.Plantarum strains may be useful as potential probiotic candidates.