Saba Salehi Nezhad - Department of Biology, Alborz Campus, University of Tehran, Tehran, Iran
Javad Hamedi - Department of Biology, Alborz Campus, University of Tehran, Tehran, Iran Department of Applied Biology (Microbial Biotechnology), School of Biology, College of Science, University of Tehran, Tehran, Iran
Mehran Habibi Rezaei - Department of Applied Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran

BACKGROUND AND OBJECTIVESMembers of Leuconostoc genus are producers of diverse compounds that have been used in various food and medical industries. These bacteria produced more than ۳۰ bacteriocins with various activity against various g+ and g- bacteria. However, antibacterial activity against Salmonella has not been reported previously. Leuconostoc mesenteroides subsp. mesenteroides UTMC ۳۸۲۱ was isolated, previously. In the current research, to avoid re-isolation of previously discovered bioactive compounds, we developed a differential method based on the physicochemical and biological characteristics of previously discovered bacteriocins of Leuconostoc species. This method was used to differentiate the bioactive compounds of the isolate.MATERIALS AND METHODSThe UTMC ۳۸۲۱ strain was cultured in MRS broth and incubated at ۲۸ oC for ۲۴ h. After removing the biomass by centrifugation at ۴۰۰۰ rpm for ۱۵ min, the supernatant was extracted with ethyl-acetate. The solvent was evaporated at reduced pressure and temperature, and the antimicrobial activity of the metabolite was examined using the agar diffusion method against seven test microorganisms. Additionally, the effect of various temperatures (۵۰°C, ۶۰°C, ۷۰°C, ۱۰۰°C, and ۱۲۰°C) and times (۱۵, ۳۰ minutes) on the bioactivity of the metabolites against Salmonella was detected.RESULTS AND DISCUSSIONThe metabolite(s) of Leuconostoc mesenteroides UTMC ۳۸۲۱ are thermotolerant (۱۲۰ oC, ۳۰ min) and active against Salmonella, Pseudomonas, and some other g+ and g-bacteria, unlike other metabolites of members of Leuconostoc genus.CONCLUSIONThe method introduced in this research is an inexpensive and applicable method for differentiating and screening Leuconostoc bacteriocins. Considering the unique characteristics of Leuconostoc mesenteroides subsp. mesenteroides UTMC ۳۸۲۱ metabolites, further research is encouraged to determine whether the metabolite(s) can be applied in food industriy and aviculture.

Bacteriocins, Lactic acid bacteria, Leuconostoc, Salmonella