Traditional fermented dairy products serve as a rich reservoir of functionally active lactic acid bacteria (LAB), which produce various bioactive metabolites with potential antimicrobial properties. Mastik, a distinctive handmade dairy product, is traditionally produced in the Elazığ, Tunceli, and Erzincan regions of Turkey. It is characterized by a multi-stage fermentation and maturation process that supports a complex microbial ecosystem. Despite its rich microbiological heritage, the antibacterial potential of postbiotics derived from mastik remains largely unexplored. Bacteria isolated from mastik samples were incubated in MRS broth at 37 °C for 48 hours to produce postbiotics. Bacterial cells were inactivated by heat treatment at 70 °C for 30 minutes to obtain whole-cell postbiotic. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of the prepared postbiotics against Salmonella Typhimurium (ATCC 14028), Listeria monocytogenes (RSKK 472), and Escherichia coli O157:H7 (ATCC 43894) were determined by the liquid microdilution method. According to the analysis results, the MIC value was determined as 15 mg/mL for all pathogens tested. The MBC values were found to be 60 mg/mL for S. Typhimurium and L. monocytogenes, and 30 mg/mL for E. coli O157:H7. The findings indicate that the postbiotic provides broad-spectrum inhibition against both Gram-positive and Gram-negative bacteria. In conclusion, it has been demonstrated that traditional fermented products like mastik, owing to their rich microbial ecosystems, hold significant potential for the development of natural bioprotective agents. It is recommended that the active compounds of the postbiotics obtained be more thoroughly characterized and validated in food model systems.

Mastik, postbiotic, antibacterial activity, MIC, MBC, food safety