"Metabolically structured population models: a unifying framework for microbial ecology and evolution"Koffel, ThomasCells grow by acquiring external resources and transforming them internally, forming new cells as they divide. Metabolic networks focus on the flow of such resources within the cell as they undergo series of biochemical reactions. How population growth emerges from the dynamics of these complex networks of metabolic reactions remains unclear. Population growth is a central ecological concept, so modeling its emergence is essential to understand the forces that shape microbial communities and their evolution. In this talk we present a novel theoretical framework that builds on the ecological theory of structured populations to model the growth of a population of cells whose intracellular dynamics are driven by an arbitrarily complex metabolic network. We show that the emergent growth rate of the population is driven by what we call limitation regimes, which capture how the various metabolite limitations within the network combine to determine growth. Changes in resource availability lead to switches between these limitation regimes, capturing the mechanisms of growth colimitation. In addition, we discovered alternative metabolic states, where a population of cells follows different limitation regimes depending on the initial metabolite concentrations. We first apply our framework to a minimal metabolic network of cells limited by two essential resources to illustrate the approach, and then to E. coli’s glycolysis pathway to showcase its capabilities on more realistic networks. By integrating metabolic networks into the theory of population dynamics, our work provides a mechanistic foundation for understanding the structure and evolution of microbial communities. |
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