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  • Isolation of Lactobacillusgenus with probiotic traits from traditional yogurts of zanjan and determination of their super natant antibacterial effects against important intestinal pathogens
  • Narges Asadi,1 Mohammad Asadi,2 Asghar Mirzakhani,3 Zahra Momeninasab,4 Hasan Hasanzadazar,5 Davoud Afshar,6,*
    1. Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, Iran
    2. Department of Biology, Islamic Azad University Branch, Urmia, Iran
    3. Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, Iran
    4. Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, Iran
    5. Department of Food Safety and Hygiene, Zanjan University of Medical Sciences, Zanjan, Iran
    6. Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, Iran


  • Introduction: Local yogurts like commercial probiotic yogurts are compounds that have probiotic bacteria like Lactobacilus spp. which exhibit suitable antimicrobial activity. nevertheless, there are limited studies onprobiotics species of local yogurts, especially in Zanjan city. Therefore, the present study was aimed to isolate probiotic Lactobacilus species form a commercial and Zanjan local yogurtsand their antimicrobial properties was also evaluated againt some pathogenic bacteria.
  • Methods: In the present study, 44 samples of local yogurts, 7 commercialsyogurts and one probioticscapsule were collected, inoculated into MRS with pH:3, and incubated at 37 °C for 24 h under microaerophilic condition. The growth positive samples were sub-cultured on MRS agar and incubated as above mentioned conditions. TheLactobacillussuspicious bacteria were isolated based on morphological and biochemical tests.to evaluate bile resistance property, all strains were cultured into MRS broth containing 0.03% bile. Bile and acid resistant Lactobacillus species were identified bysequencing of 16 srRNA gene. Anti microbial effect of strains was performed against Shigelladysentariae,S. flexneri, S. boydii, and S. sonnei,Salmonellatyphi, S. enteritidis, Yersiniaenterocolitica, Aeromonas hydrophila,Vibriocholerae,Clostridioides difficile and Bacillus cereusby well diffusion method.
  • Results: From 44 samples of local yogurts,7 probiotic strainsincluding 5Lactobacillushelveticus, 1 L. letivazi and 1 strain of L. selangorensis was isolated. In the probiotic supernatant antimicrobial test, Lactobacillushelveticusstrains showed the most inhibition effect with15mm inhibitory zone diameters. All of probiotics in commercial probiotic yogurts and capsule have belonged to Lactobacillusacidophilus species and despite of inhibitory effectagainst some pathogenic bacteria, had not inhibitory effect against S. tyohi, Vibriocholerae, and Bacillus cereus.
  • Conclusion: The results of the present study showed that local yogurts in Zanjan city have Lactobacillus species with probiotic potencial ability and their antimicrobial properties are similar to commercial probiotic yogurts.
  • Keywords: Intestinal pathogens, probiotic, Lactobacillus