Metabolic overflow prevents ecological collapse in microbial populations

Abstract

Metabolic overflow is defined by the excretion of partially oxidized byproducts, such as acetate, ethanol, and lactate, which could otherwise be used to produce energy. This behavior, widespread across diverse biological systems, is paradoxical because it suggests a seemingly wasteful use of resources that could instead be employed to maximize energy production. In this work, we investigate the ecological implications of metabolic overflow, using bacterial acetate metabolism as a model. We formulate a second-order generalization of the logistic growth equation, incorporating resource availability and acceleration dynamics to provide an explicit mechanistic link between metabolic overflow and ecological collapse. We demonstrate that acetate-mediated growth deceleration reduces the risk of overshoot and collapse, especially under conditions of resource oversupply. By inhibiting excessive proliferation, acetate overflow enhances the survival and stability of bacterial communities in fluctuating environments. In this context, acetate acts as a quorum-sensing signal, coordinating population-wide responses and enabling the active regulation of growth rates before resource exhaustion occurs. Our findings suggest that overflow metabolism is an adaptive strategy evolved to mitigate the risk of ecological collapse and stabilize microbial populations. These insights highlight the dual role of metabolic byproducts as both inhibitors of growth and regulators of population dynamics, with significant implications for microbial ecology and biotechnological applications.