Document Type : Original Article
Authors
1
M.Sc., Department of Microbiology, TeMS.C., Islamic Azad University, Tehran, Iran.
2
Department of Microbiology, TeMS.C., Islamic Azad University, Tehran, Iran.
3
Associate professor, Department of Veterinary Hygiene, SR.C., Islamic Azad University, Tehran, Iran.
10.22034/zmm.2026.737176
Abstract
Background and Objectives: Lactic acid bacteria (LAB) are a group of probiotic bacteria with health promoting effects on the human gastrointestinal tract. Dairy products, particularly raw milks, are considered a rich source of probiotics. This study aimed to carry out the molecular identification of LAB with probiotic properties isolated from raw buffalo milk in Behbahan city, Iran.
Materials and Methods: Raw milk samples were cultured on MRS agar, and isolates were screened based on phenotypic and biochemical characteristics. Probiotic properties including acid tolerance, simulated gastric juice (pepsin and trypsin), and bile salts (0.3%), as well as physiological characteristics such as hydrophobicity, auto and coaggregation, were examined. Antibiotic susceptibility and antimicrobial activity of the isolates against four pathogenic bacteria were also evaluated. Finally, selected isolates were identified by 16S rRNA gene sequencing.
Results: From 28 isolated strains, 17 exhibited typical LAB characteristics, i.e., Gram positive coccobacilli, catalase and oxidase negative). Four isolates showed the ability to grow under acidic conditions (pH 2.5 and 4), in simulated gastric juice (pepsin and trypsin), and in the presence of bile salts (0.3%). The isolate, D20 was susceptible to ampicillin, vancomycin, and penicillin and displayed the highest autoaggregation (52.27%). The isolate, B7 showed the highest coaggregation with E. coli (31.72%) and the highest antibacterial activity against B. cereus (inhibition zone diameter: 22 mm). The isolate, A3 exhibited the highest hydrophobicity (39.1%) as well. Sequencing results revealed that three isolates belonged to Enterococcus faecium and one isolate belonged to Enterococcus faecalis.
Conclusion: According to the results, raw Buffalo milk from Behbahan city is a rich source of probiotic bacteria. This study can provide comprehensive information for the establishment of probiotic culture collections in the country.
Keywords
Zand Molecular Microbiology