Eubiosis and dysbiosis : where are the signatures ?

This lecture was an opportunity to revisit the "Koch postulates" in the light of complex microbial populations whose qualitative and quantitative alterations, or dysbiosis, are associated with pathologies. Is it possible, in order to establish a causal link, to apply unchanged the "Koch postulates" that were established for a single pathogenic microorganism and not for a more or less diverse microbial population? We propose the notion of "Koch's ecological postulates", and attempt to identify criteria for establishing causality as closely as possible.