Structure-function landscape of a closed microbial ecosystem

Ecosystem persistence depends on emergent stable nutrient cycles to replenish resources. In a previous study, we established closed microbial ecosystems (CES) as models of nutrient cycling in ecosystems. CES are materially closed microbial communities that persist by supporting self-sustaining nutrient cycles using only light as an input. We showed that CES composed of bacterial communities and a model phototrophic alga self-assemble to cycle carbon for months. Furthermore, we showed that replicate CES that persistently cycle carbon exhibit a conserved set of metabolic capabilities despite strong differences in the taxonomy of the bacteria present. However, fully exploring the dependence of carbon cycling on community composition is experimentally challenging. Therefore, we developed a consumer-resource model of emergent carbon cycling in CES. The model incorporates thermodynamic considerations of metabolic reactions and recycling of necromass. Our model recapitulates the dependence of phototroph-heterotroph interactions in the establishment of carbon cycles.  Using this model, we present a detailed exploration of how the bacterial catabolic traits and community structure impact emergent nutrient cycling in CES.