Characterization of antimicrobial activity of three Lactobacillus plantarum strains isolated from Chinese traditional dairy food

Many Lactobacillus plantarum strains can secrete some antimicrobial substances and be added to food as antimicrobial agents and preservatives. In this study, three L. plantarum strains (P1, S11, and M7) with strong antimicrobial activity against three pathogenic bacteria were isolated from Xinjiang traditional dairy products. Five common organic acids produced by fermentation of strains play a key role in inhibiting three pathogenic bacteria. At the same pH, the antimicrobial activity of the fermentation broth against Escherichia coli and Salmonella is stronger than that of the organic acid alone. Thus, three kinds of antimicrobial agents (P1-1, M7-1, and S11-1) mixed with five common organic acids were produced. Moreover, the antimicrobial activity against Salmonella ASI.1174 of the antimicrobial agents was about 30% higher than that of the fermentation broth. In addition, organic acid antimicrobial agents combined in different proportions can inhibit different pathogenic bacteria. According to this result, it is a potential approach to develop novel antimicrobial agents used in food preservation by mixing different organic acids.