Description:

Microbes live in complex communities that play a central role in global nutrient cycles.  The flow of nutrients around these cycles are defined by and defines microbial community structure and metabolic function.  As such, a primary concern of microbial ecology is understanding the eco-evolutionary process by which functional microbial communities arise. How does the metabolic function of a microbial community emerge from the genes, species, and interactions present? How are communities organized by nutrient fluxes? We address these questions experimentally in two model systems. In our first study, we ask: can we predict the flow of metabolites through a community from the genes each community member possesses?  We take a bottom-up approach using denitrification as a model process whereby bacterial communities reduce oxidized nitrogen compounds through a cascade of four reactions. Using natural isolates, sequencing and metabolite measurements we develop a statistical approach to mapping community level denitrification rates to genomic composition. In our second study, we ask: how do communities self-organize to sustain nutrient cycles? To address this question we take a top-down approach using closed microbial communities - hermetically sealed microbial biospheres which persist indefinitely when supplied with only light - as model systems.  Closed ecosystem persistence relies on the sustained cycling of carbon driven by photosynthesis.  We present a new, high-precision, measurement of carbon cycling in closed ecosystems. We show that complex microbial consortia can self-organize to persistently cycle carbon. We present preliminary work to understand the mechanisms by which these microbial biospheres accomplish stable nutrient cycling.

Professor Seppe Kuehn, University of Illinois at Urbana-Champaign

Host: Michelle Driscoll

Keywords: Physics, Astronomy, Complex Systems