Isolation and identification of beneficial microorganisms of traditional kefir beverage and its effects on Salmonella typhimurium and Listeria monocytogenes pathogens

Introduction- Kefir milk might have different ratios of microflora according to their origin(۱). These microorganisms that constitute kefir grains are enclosed in a polysaccharide known as kefiran, which is a heteropolysaccharide and is mainly produced by Lactobacillus kefiranofaciens(۲). This study aimed to isolate and identify beneficial microorganisms and evaluate the antimicrobial activity of kefir beverage against two important food-born pathogens including Salmonella Typhimurium and Listeria monocytogenes.Material and Methods- Microorganisms were identified by polymerase chain reaction method (PCR) with specific primers and antimicrobial activity was evaluated by disc diffusion method(۳, ۴).Findings- microorganisms were identified as the natural inhabitants of the kefir grains, Leuconostoc lactis, Lactococcus lactis subspecies lactis, Streptococcus cremoris, Enterococcus faecalis, Enterococcus faecium, Lactobacillus helveticus, Leuconostoc mesenteroides, Lactobacillus fermentum, Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus casei, Bifidobacterium langum, Saccharomyces cerevisiae, and Pischia fermentas. Also, the results obtained from the disk diffusion method showed the inhibitory effect of kefir milk on Salmonella Typhimurium and Listeria monocytogenes with an inhibitory average diameter of ۸.۳-۴.۰۴ to ۹.۱-۲.۸۰ and ۳.۴-۳.۰۵ to ۶.۶-۳.۰۵ mm, respectively. The highest inhibitory effect was observed against Salmonella Typhimurium.Conclusion- The results of this study showed that traditional kefir milk produced using kefir grains contained different species of lactic acid bacteria and yeasts. Kefir milk also exhibited bactericidal activity against Salmonella and Listeria monocytogenes.

کلیدواژه ها:

kefir beverage ، lactic acid bacteria ، yeast ، antimicrobial activity ، food-borne pathogen