Metabolic allocation strategies of Geobacter in electroactive biofilms to adapt to varying acetate supply concentrations

Abstract

Geobacter species play a key role in acetate-fed electroactive biofilms (EABs), but their competitiveness varies with acetate supply concentration for unclear reasons. By continuously supplying different concentrations of acetate, we discovered an adaptive metabolic strategy of Geobacter biofilms, centered on regulating carbon allocation to protein synthesis, polysaccharide production, and the TCA cycle. Growth and reproduction were prioritized in response to acetate limitation under low supply concentrations, whereas catabolic efficiency was enhanced when acetate was sufficient. Excess acetate also induced the toxic effects of intracellular acetyl-CoA accumulation, triggering metabolic processes including stress responses, acetyl-CoA hydrolase synthesis, and carbon source storage. These metabolic adaptations ultimately determined the competitive niche of Geobacter in wastewater EABs, allowing for population dominance under acetate limitation and enhancing current production when acetate was abundant. Our findings give new insights into Geobacter's survival strategies in various environments with different acetate availability, and provide a theoretical basis for targeted regulation of the performance and stability of EABs to achieve environmental functions.