The structure-function problem in microbial communities

Microbial communities exhibit complex abundance dynamics driven by a myriad of interactions between constituents. Despite the apparent complexity of their dynamics, communities consistently perform critical functions across the biosphere including protecting hosts from pathogens and driving global biogeochemical cycles. How do functional aspects of communities emerge from interactions between constituents? How does the structure of a collective – the genotypes present, their phenotypes and interactions – determine emergent community function? How does Nature construct such robustly functional communities?



In this talk, I will present our recent work on this ‘structure-function problem’ in communities. Using denitrification, a key part of the nitrogen cycle, as a model process we showed that the dynamic flux of metabolites through a community can be predicted simply from knowledge of the genes each strain possesses. Thus, the details of which species are present is not necessary to predict function, and instead genotypes and resulting phenotypes fully determine metabolite flows. We affirm this finding independently in very complex communities that exhibit self-sustaining nutrient cycles. I will present recent work extending these insights into understanding the structure and function of natural communities in soils, and the problem of designing communities with specific functional properties.