Emergent Physiological Properties of Diauxic Growth and Their Influence on Microbial Ecological Dynamics

Microbial communities are remarkably complex ecosystems, often composed of hundreds of species competing for a limited pool of nutrients. Predicting their ecological dynamics in dynamic environments requires a predictive understanding of how community members adapt their physiology to anticipate and respond to environmental fluctuations. Here, we present a low-dimensional model of cellular growth that accounts for various physiological phenomena, including diauxic adaptation to rapid changes in nutrient availability. We provide different candidate mechanisms for metabolic pathway regulation and identify the conditions under which they yield lag phases–periods where cellular growth approximately ceases–and show that their duration linearly scales with the turnover rate of intracellular tRNA pools. Using this model, we explore in silico the ecological dynamics of communities whose microbes share this physiological principle, but employ different metabolic strategies in boom-and-bust nutrient environments. Finally, we examine how species coexistence emerges in this system and its sensitivity to different distributions of lag times within the community.