Abstract:In this experiment，a strain of Propionibacterium freudenreichii was used as the starting strain，and its metabolites were tested for the inhibition of Escherichia coli（E.coli）and Salmonella by changing the fermentation medium，inoculum volume and initial pH value and compared with the antibacterial effect of potassium sorbate.The results showed that all the three fermentation media had a certain inhibitory effect on E.coli and Salmonella，and the inhibitory activity values of the metabolites of the strain were 25.3 AU/mL and 18.3 AU/mL，respectively.The antibacterial activity values were better than that of 0.1 % potassium sorbate（21.1 AU/mL and 14.1 AU/mL）；for the inoculum size，the best inoculation rates against E.coli and Salmonella were 6 % and 5 %，its antibacterial activity values were 28.1 AU/mL and 18.0 AU/mL，respectively，and its antibacterial effect was better than the antibacterial value of 0.1%potassium sorbate；In terms of different initial training pH value，the optimal initial pH value for bacteriostatic activity of E.coli and Salmonella was 6.5 and 6，respectively，antibacterial activity were 27.6 AU/mL and 14.5 AU/mL，its bacteriostatic effect was better than that of 0.1%potassium sorbate.Therefore，the propionin obtained by fermentation under suitable conditions were better than that of potassium sorbate in inhibiting E.coli and Salmonella.In short，the results obtained from this work will provide evidence for the research and development of novel nature-based preservative.