In vitro and in vivo investigations of probiotic properties of lactic acid bacteria isolated from Chinese traditional sourdough.

A total of 88 lactic acid bacteria (LAB) strains were isolated from Chinese traditional sourdough and five of them were selected based on their bile resistance. All the five strains were identified as Lactobacillus plantarum by 16S rRNA gene sequencing. In vitro probiotic properties of the L. plantarum strains including tolerance to simulated gastrointestinal conditions, aggregation activity, and cholesterol removal ability were assessed. Two representatives, L. plantarum ZJUFT34 and L. plantarum ZJUFT17, were intragastrically administered to male C57BL/6J mice of 4-week age for 6 weeks to evaluate their in vivo health-promoting effects. The results indicated that L. plantarum ZJUFT34, L. plantarum ZJUFHN9, and L. plantarum ZJUFAH5 could survive the 3-h incubation in simulated gastric juice with a pH value of 2.0, while L. plantarum ZJUFT32 and L. plantarum ZJUFT17 exhibited better autoaggregation activities and coaggregation activities with pathogens. All the strains showed a cholesterol removal ability in vitro. However, L. plantarum ZJUFT34 or L. plantarum ZJUFT17 administration did not significantly change the serum total cholesterol in vivo. But the ratio of high-density lipoprotein cholesterol to low-density lipoprotein cholesterol was significantly increased by the L. plantarum administration. Besides, L. plantarum ZJUFT17 significantly lowered serum tumor necrosis factor (TNF)-α concentrations. Furthermore, the administration of the LAB strains showed significant influences on lipid metabolism-related gut microbiota. These findings suggested that the L. plantarum strains may benefit the prevention of metabolic syndrome.