Isolation, identification and probiotic characteristics of acid-producing and acid-resistant Lactobacillus strains

Objective  To isolate, screen and evaluate Lactobacillus strains with excellent acid-producing ability, and offer materials for application of Lactobacillus in feed industry.

Method  Using acid flavor food as samples, we isolated and screened Lactobacillus strains, initially according to the size of calcium dissolving zone and subsequently according to acid tolerance. The acid-producing abilities, growth characteristics, low-pH and bile salt tolerance, and antibacterial activities of Lactobacillus strains screened out were further studied.

Result  Ten Lactobacillus strains capable of growing at pH 3.0 were obtained. Strain SC3A and DJ3 were identified as L. pentosus, and strain SC15, SC16, DJ9B, DJ10C, SC8, DJ8A, DJ8B and DJ9A were identified as L. fermentum. The acid-producing abilities, fermentation growth rate and antibacterial activities of L. pentosus strains DJ3 and SC3A were significantly superior to those of the L. fermentum stains. The L. fermentum strains DJ8A and DJ9B showed higher tolerance to acid environment and bile salt.

Conclusion  Ten Lactobacillus strains obtained from acid flavor food have strong acid-producing ability, acid tolerance and antibacterial activity, and have application potential in food and feed industries.