Isolation and identification of Lactobacillus bacteria with probiotic potential from traditional dairy in Kerman

Background: As lactobacilli possess an antagonistic growth property, therefore they may be used as bioprotective agents for infection control. The aim of this study was to investigate the antagonistic effect of lactobacilli isolated from local dairy. Materials and Methods: In this study ۲۶ species of Lactobacilli were isolated from milk, homemade yoghurt and cheese. Each isolated bacteria was tested for its tolerance to acidic environments at pH (۲.۰, ۳.۰, and ۴.۰) and bile salt concentrations (۰.۳, ۰.۵ and ۱% w/v). Also, isolates were further tested for their antimicrobial activity against common pathogenic bacteria such as Enterococcus feacalis, Listeria monocytogenes, Staphylococcus aureus PTCC ۱۱۱۲, Escherichia coli PTCC ۱۳۳۰ and Bacillus cereus PTCC ۱۰۱۵ by using the agar well method. Then the strains that are not only resistant to acidic conditions and bile salts but also have antimicrobial activity, were identified by ۱۶S rRNA gene sequencing. Results: In this study, most of isolated Lactobacilli were found to inhibit growth of pathogens (۹۶.۱۵%). ۶۱.۵% and ۸۴.۶۲% of isolated lactobacilli tolerated to pH ۲ and ۰.۳% bile salt. Only two strains, ۵۳C and ۲۲CL, were more resistant to pH ۲ and high concentration of bile salt. The Phylogenetic analysis based on ۱۶S rRNA sequencing revealed that two strains (۵۳C and ۲۲CL) belong to species of Lactobacillus casei. Conclusions: According the results the two isolated resistant strains can be employed as probiotic starter in probiotic dairy products preparation.

کلیدواژه ها:

Lactobacillus ، probiotic ، antimicrobial ، ۱۶S rRNA gene ، اکتوباسیلوس ، پروبیوتیک ، ضدمیکروبی ، ژن ۱۶S rRNA