Activity quantification and PCR identification of Lactobacillus plantarum isolated from Iranian traditional pickled products

Introduction and purpose:There is a worldwide trend for fortified and fermented foods containing live beneficial probiotic bacteria. Pickled cucumber is a popular fermented food, which is widely used in Iran. The aim of this study was to quantify the antibacterial effect of lactic acid bacteria isolated from various Iranian traditional pickled products.Materials & methods:Levels of lactic acid bacteria in both brine and solid materials of Iranian traditional pickled products were assessed by conventional pour plating technique on MRS media. Values of pH plus NaCl contents of the individual pickled products were also determined. Antibacterial effect of Lactobacillus plantarum strain isolated from pickled products was examined against Salmonella typhi using spot and well-test techniques.Results:None of the marketed industrial pickled products contained viable bacteria. The lactic acid bacteria isolated from all traditional pickled products was confirmed to be Lactobacillus plantarum. The number of lactic acid bacteria in the brine as well as solid material of Iranian traditional pickled products was 1×105 to 2.05×107 cfu.ml-1 and 8.2×103 to 6.5×106 cfu.g-1 respectively. All products had NaCl content of less than 1% and the pH of the products ranged over 3.1-3.5. All the isolates identified as L.plantarum by conventional biochemical tests were confirmed by PCR method using the species specific 16s rRNA primer.Discussion & conclusion:All traditional pickled products contained viable lactic acid bacteria in both brine and solid materials while none of the industrial marketed products contained viable bacteria. This could be the effect of added preservatives or spices, which could negatively affect lactic acid bacterial counts in the industrial products. Traditional pickled products could be considered as good candidates for probiotic foods with beneficiary effect on consumer health.

Keywords:

Lactobacillus plantarum , probiotic , Antibacterial effect quantification , Iranian traditional pickled products