پریسا فتحی رضایی

BACKGROUND AND OBJECTIVES Probiotics are microorganisms that are beneficial for health when used in sufficient quantity.Various bacterial genera most commonly used in probiotic preparations are Lactobacillus, Bifidobacterium, Escherichia, Enterococcus, Bacillus and Streptococcus. Nowdays, the research suggests that these “healthy” bacteria have beneficial effects on gastrointestinal dysfunctions, including diarrhea, as well as the immune system and conditions such as allergy, in children, adults, and in the oral cavity. MATERIALS AND METHODS To identify the isolated bacteria from traditional Maragheh yogurt, biochemical and microbial tests including; gram staining, oxidase, catalase, hemolysis, acid and bile salt resistance mobility, nitrate reduction, SIM, sugar fermentation, antibiotic resistance, antimicrobial tests were carried out. The asparaginase and glutaminase production was evaluated by raid plate assay. The molecular identification of the isolate was down through DNA extraction, PCR amplification of 16S rRNA gene, electrophoresis and construction of phylogenetic tree of the isolate via neighbor-joining method by BioEdit and MEGA softwares. RESULTS AND DISCUSSION According to the results, M24 isolate showed; gram-positive morphology, negative results for catalase and oxidase tests, resistance to bile salts and acidic pH, absence of hemolysis, resistance to antibiotics, sugar fermentation and nitrate reduction. The results of molecular investigations revealed that the isolate had the highest genetic similarity (97%) to Limosilactobacillus fermentum CECT562(T)AJ575812. The nucleotide sequence of the M24 isolate has been recorded in the NCBI database under accession number OQ568204. Furthermore, the isolate produced asparaginase and glutaminase enzymes. CONCLUSION Due to the probiotic potential of the isolate, its encapsulation via biopolymers is running in our lab.