Ecology of the gut microbiota and colonization resistance: mechanisms and therapeutic implications

The human gastrointestinal (GI) ecosystem is a highly dynamic environment and provides diverse microbial habitats for the gut microbiota, which are shaped by environmental factors, metabolic processes, and immune responses. The host-microbiota interactions in the gut form a balanced yet adaptable network. When invading microorganisms enter the GI tract, they deploy multiple strategies to overcome both host defences and competition from the resident microbiota. In turn, the host and native microbiota have evolved sophisticated mechanisms to prevent the colonization of invading organisms, collectively termed colonization resistance. Deciphering the mechanisms of interplay in the host‒microbe and microbe‒microbe relationships in the gut offers crucial insights into therapeutic interventions aimed at restoring or maintaining gut microbial homeostasis.