In vitro and in vivo evaluation of Lactobacillus strains and comparative genomic analysis of Lactobacillus plantarum CGMCC12436 reveal candidates of colonise-related genes.

The presence of Lactobacillus strains in dairy products and the intestinal tracts of humans and animals is frequently considered to have beneficial effects on gut health. In this study, five L. plantarum and five L. casei strains from fermented food origin were isolated and compared to characterise their functional properties, including generation time, survival in the gastrointestinal environmental conditions and carbohydrate utilisation. The growth rate of L. plantarum CGMCC12436 was the same level with that of L. plantarum strain ST-III. The L. plantarum CCFM605 and CGMCC12436 maintained the similar levels of cell numbers under the simulated gastrointestinal tract, which were comparable to the cell numbers of L. plantarum strain ST-III. The L. casei CCFM236 and CGMCC12435 exhibited significant higher survival rates than CCFM5 in the duodenal juice. The evaluation of their colonisation in the mouse gut indicated that the L. plantarum strain ST-III, CCFM595 and CGMCC12436 could colonise relatively longer than other tested strains. Furthermore, two strains were selected for characterisation of whole genome sequences. Among the identified key genes responsible for the functional properties, we found that the cpsD gene cluster in L. plantarum CGMCC12436 may be closely associated with its colonisation ability in the mouse gut during and after discontinuing the strain administration. In conclusion, we revealed the functional properties of Lactobacillus strains in vitro assays and colonisation properties in the mouse gut, and elucidated the relevant genes involved in the tolerance or colonisation in gut using comparative genome analysis.