There are 10 times more bacteria than human cells in our body, including probiotics, pathogens and commensal bacteria, which collectively modulate human disease and health. We are interested in addressing the molecular mechanisms of interaction between gut microbes and host environment, specifically (1) the composition and development of core microbiota in host gut environment; (2) Identification and mechanism of probiotic factors.3）Upgrade the probiotics and probiotic factors via genetic or chemical modification.