Cross-feeding shapes both competition and cooperation in microbial ecosystems

Pankaj Mehta; Robert Marsland III

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arXiv · 2110.04965

Cross-feeding shapes both competition and cooperation in microbial ecosystems

Pankaj Mehta·Robert Marsland III

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Abstract

Recent work suggests that cross-feeding -- the secretion and consumption of metabolic biproducts by microbes -- is essential for understanding microbial ecology. Yet how cross-feeding and competition combine to give rise to ecosystem-level properties remains poorly understood. To address this question, we analytically analyze the Microbial Consumer Resource Model (MiCRM), a prominent ecological model commonly used to study microbial communities. Our mean-field solution exploits the fact that unlike replicas, the cavity method does not require the existence of a Lyapunov function. We use our solution to derive new species-packing bounds for diverse ecosystems in the presence of cross-feeding, as well as simple expressions for species richness and the abundance of secreted resources as a function of cross-feeding (metabolic leakage) and competition. Our results show how a complex interplay between competition for resources and cooperation resulting from metabolic exchange combine to shape the properties of microbial ecosystems.

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Pankaj Mehta, Robert Marsland III. 2021-10-11. Cross-feeding shapes both competition and cooperation in microbial ecosystems. https://arxiv.org/abs/2110.04965

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