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.

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Aims To identify the mechanism in which way maltodextrin enhance bile tolerance in Lactobacillus plantarum Lp‐115. Methods and Results Based on determining the OD600 value and counting the numbers of viable cells by the pour plate method, the results showed that maltodextrin could not promote the strain growth directly, but could enhance the tolerance of bile in Lp‐115. The OD600 value of L. plantarum Lp‐115 cultured in MRSB broth with maltodextrin was three times higher than the control value. After supplementing the medium with 4·0% maltodextrin, the highest survival rate was observed when the bile concentration is 0.3%. Conclusions In summary, maltodextrin exhibited a significant improvement of bile tolerance and it could enhance cell hydrophobicity, shift the fatty acid composition of the membrane and induce the expression of a bile salt hydrolase gene (pva3) significantly. Significance and Impact of the Study This is the first report concerning the mechanism of maltodextrin enhancing the bile tolerance. This study promotes the application of maltodextrin as a choice to protect probiotic L. plantarum strains against the bile salt stress.