Microbial redox cycling enhances ecosystem thermodynamic efficiency and productivity

Microbial life in an ecosystem with low energy supply has been considered to employ two energy utilization strategies. The first is energy conservation at an individual level, while the second is energy use optimization in response to the availability of energy resources. Here, using an oxidation-reduction (redox) reaction network model where microbial metabolic pathways are established through multiple species-level competition and cooperation within a redox reaction network, we hypothesize that microbial ecosystems can move forward to increase energy use efficiency, namely an energy efficiency strategy at the community level. This strategy is supported by microbial functional diversity that enables species to interact with others in various ways of metabolic handoffs. Moreover, the high energy use efficiency is attributable to the mutualistic division of labor that increases the complexity of metabolic pathways, which actively drives material cycling to exploit more energy.