External seminar - Seppe Kuehn (University of Chicago)

Microbial communities exhibit complex dynamics driven by evolutionary, ecological, environmental processes. Despite this complexity, microbiomes retain reliable functional properties, such as the metabolic activities that drive global biogeochemical cycles. In order to design or predict microbiome function we need to understand how it emerges from eco-evolutionary processes playing out in dynamic natural environments. Using bacterial denitrification -- a key metabolic process in soil -- I will present results demonstrating how natural variation can be leveraged to understand functional microbiomes. First, I will briefly show how community-level metabolism can be predicted from genomes by exploiting natural variation in bacterial traits (Gowda et al. 2022). Next, I will show that genomically encoded traits and their ecological interactions contribute to conserved global patterns in gene content (Crocker et al. 2024). Finally, I will show that simple models and quantitative measurements can reveal the ecological mechanisms mediating the metabolic responses of soil microbiomes to environmental change. This final study, which will form the bulk of my presentation, shows how simple mathematical phenomenology combined with quantitative measurements can provide deep insights into the collective properties of very complex microbial ecosystems. These studies lay a path for looking to nature to understand how collective metabolic function in communities arises from evolved traits, ecological interactions, and environmental fluctuations.