Biochemical and molecular identification of probiotic bacteria isolatedfrom traditional dairy products of Maragheh County abstract
BACKGROUND AND OBJECTIVESThe word probiotic is derived from the Greek word probios, meaning for life. This term wasfirst used by Stillwell and Lilley in 1965 for microorganisms that have a positive effect on thegrowth and balance of intestinal microbial flora. Dairy products are very favorable carriersfor probiotics. Probiotics are found in dairy products such as milk, yogurt, cheese, ice cream,buttermilk, and sour cream. In addition to live bacteria, probiotic yogurts provide the hostwith nutrients such as biological peptides and calcium. Lactic acid bacteria are among themost important probiotics, the most famous of which are Bifidobacterium and Lactobacillusgenera.MATERIALS AND METHODSIn this study, M09 isolate was isolated from traditional yogurt samples of Maragheh. Afterpurification, preliminary tests were conducted to evaluate probiotic characteristics such asgram, catalase, hemolysis, oxidase, acid and bile salts resistance tests and biochemical andmicrobial tests including sugar fermentation, SIM, nitrate reduction, antibiotic resistance andantimicrobial. In order to the molecular identification of the isolate, DNA was extracted, 16SrRNA gene amplified by PCR, PCR result visualized using gel electrophoresis. Then, thephylogenetic tree of the isolate was constructed by neighbor-joining method via BioEdit(version 7.2) and MEGA (version 7) softwares.RESULTS AND DISCUSSIONAccording to the biochemical, phenotypic and microbial findings, the isolate was grampositivebacteria, negative results for catalase and oxidase tests, resistance to bile salts andacidic pH, absence of hemolysis, resistant to antibiotics, able to sugar fermentation andnitrate reduction. The molecular analysis results showed that the isolate 99% similar toLimosilactobacillus fermentum (CECT 562(T) AJ575812) in terms of genetic affinity and thenucleotide sequence of the isolate was registered in the gene bank with the accession number(OQ568196).CONCLUSIONThe isolated bacteria from traditional Maragheh yogurt showed probiotic potential and couldbe apply in food industry.