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PLoS Comput Biol. 2016 Jun 17;12(6):e1004986. doi: 10.1371/journal.pcbi.1004986. eCollection 2016 Jun.

Pervasive Selection for Cooperative Cross-Feeding in Bacterial Communities.

Author information

1
Department of Bioinformatics, Friedrich Schiller University Jena, Germany.
2
Research Group Theoretical Systems Biology, Friedrich Schiller University Jena, Germany.
3
Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.
4
Research Group Medical Systems Biology, Institute for Experimental Medicine, Christian-Albrechts-University Kiel, Germany.
5
Department of Ecology and Evolution, School of Biology/Chemistry, Osnabrück University, Germany.

Abstract

Bacterial communities are taxonomically highly diverse, yet the mechanisms that maintain this diversity remain poorly understood. We hypothesized that an obligate and mutual exchange of metabolites, as is very common among bacterial cells, could stabilize different genotypes within microbial communities. To test this, we developed a cellular automaton to model interactions among six empirically characterized genotypes that differ in their ability and propensity to produce amino acids. By systematically varying intrinsic (i.e. benefit-to-cost ratio) and extrinsic parameters (i.e. metabolite diffusion level, environmental amino acid availability), we show that obligate cross-feeding of essential metabolites is selected for under a broad range of conditions. In spatially structured environments, positive assortment among cross-feeders resulted in the formation of cooperative clusters, which limited exploitation by non-producing auxotrophs, yet allowed them to persist at the clusters' periphery. Strikingly, cross-feeding helped to maintain genotypic diversity within populations, while amino acid supplementation to the environment decoupled obligate interactions and favored auxotrophic cells that saved amino acid production costs over metabolically autonomous prototrophs. Together, our results suggest that spatially structured environments and limited nutrient availabilities should facilitate the evolution of metabolic interactions, which can help to maintain genotypic diversity within natural microbial populations.

PMID:
27314840
PMCID:
PMC4912067
DOI:
10.1371/journal.pcbi.1004986
[Indexed for MEDLINE]
Free PMC Article

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