The 2027 meeting focuses on mechanistic research that gives quantifiable, cause-and-effect insight into the biology of Bacteria, Archaea, Eukarya and viruses: microbial evolution, how microbial mechanisms contribute to ecosystem function and human health, how microbial redox reactions and syntrophic interactions drive elemental cycles, and how single-cell and bulk approaches reveal microbial life. Topics include biogeochemical cycling, discovery of new microbial lineages and functions, critical mineral recovery and biometallurgy, biofuels, environmental monitoring, removal of anthropogenic contaminants, the human microbiome, computational microbiome research, and exploiting microbe-mediated mechanisms within a One Health framework, across natural and synthetic communities and holobionts. Some poster presenters are selected for short talks. As a Gordon Research Conference, the meeting presents cutting-edge and unpublished research with extended discussion after each talk, poster sessions open to scientists of all career stages, and informal exchange over communal meals.