Evaluation of tolerance to artificial gastroenteric juice and fermentation characteristics of <i>Lactobacillus</i> strains isolated from human

Abstract

Fifty-seven strains of <i>Lactobacillus</i> were isolated from fecal samples of healthy young people in Tibet, Xinjiang, and Inner Mongolia using pure culture methods. <i>Lactobacillus ruminis</i> and <i>Lactobacillus gasseri</i> were the dominant <i>Lactobacillus</i> species isolated from the intestinal microflora, accounting for 54.4% and 14.0% of the total isolates, respectively. Isolated strains were identified by 16S rRNA sequencing, and their tolerance to gastric acid and bile salt, and fermentation characteristics were evaluated. The results of experiments in vitro showed that nine of the isolated strains of <i>Lactobacillus</i> grew well at pH 3.0. After 11 h of incubation in artificial digestive juices, the isolated <i>L. plantarum</i> and the control strain <i>L. plantarum</i> P8 still had high survival rates. Most of the isolates and control isolates have strong tolerance to bile salts. The evaluation of fermentation characteristics indicated that the ability of the intestinal <i>Lactobacillus</i> to ferment skimmed milk was lower than that of the reference <i>L. plantarum</i> P8. In the process of storage, the viable count of screened isolates of human origin in fermented milk decreased to some extent, but remained above 7.01 ± 0.22 log CFU/ml, showing good storage characteristics.