Isolation and Screening of Exopolysaccharide Producing bacteria from traditional dairy products in Kerman province and Molecular identification of them

Exopolysaccharides produced by lactic acid bacteria play an important role in the improvement of sensory and textural properties of fermented dairy products. The aim of this study was to isolate and molecular identify of exopolysaccharide-producing bacteria from traditional dairy products in Kerman province. The traditional dairy product samples were collected aseptically and then cultured directly in MRS agar media. After purification, examining microscopic and macroscopic properties and performing biochemical tests, 20 strains were selected and production of EPS was measured with phenol/sulfuric acid method. The results were compared with the glucose standard curve and the amounts of production were determined. The EPS production pattern were compared with the growth pattern of the bacteria and the effects of the temperature and pH on the production of EPS were investigated. Finally, M-2 and M-26 were chosen as the top strains and identified by molecular method. Then the produced EPS was extracted and antimicrobial activity was investigated with Agar diffusion method. the results showed that the 20 isolates produced two kinds of EPS. Two isolates including M-2 and M-26 had the maximum amount of production belonged to Leuconostoc mesenteroides and Enterococcus faecium respectively. The production of the EPS in the PH 6.5-8 under the temperature 25-42˚C were investigated and the results showed that the maximum amount of production was at the 37˚C and pH=7.5 in the end of logarithmic growth. The results of this study indicate EPS production is possible by traditional dairy products of Kerman province.