Microbes, Credit: Manpreet Dhami, Tadashi Fukami and Lydia-Marie Jouber

What’s love got to do with it? Stable marriage and networks in microbial ecosystems

Sergei Maslov (Hosted by Tikhonov), Dept. of Bioengineering, Dept. of Physics, and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

Microbial communities routinely have several alternative stable states observed for the same environmental parameters. A possibility of sudden and irreversible transitions between these states (ecosystem-wide regime shifts) complicates manipulation and control of these systems. Can we predict which specific perturbations may induce such regime shifts and which would have only a transient effect?  Can we estimate the concentrations of metabolites produced and consumed by the human gut microbiome from its species composition? Here I describe several new conceptual models that address these questions. Two of our models were inspired by a decades-old economics work: the stable marriage or stable allocation problem, developed by Gale and Shapley in the 1960s and awarded the Nobel prize in economics in 2012. Using only the ranked tables of competitive abilities of microbes and their nutrient preferences, we determine all stable states of the microbial ecosystem. Each stable state is characterized by a range of environmental parameters (nutrient supply rates) in which all of its species survive. We were able to identify specific environmental perturbations shifting the system from one stable state to another, and analyze a complex interconnected network shaping nutrient consumption and production in an ecosystem.