Pervasive Selection for Cooperative Cross-Feeding in Bacterial Communities.
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.
Department of Bioinformatics, Friedrich Schiller University Jena, Germany.
Sebastian
S
Germerodt
Department of Bioinformatics, Friedrich Schiller University Jena, Germany.|Research Group Theoretical Systems Biology, Friedrich Schiller University Jena, Germany.
Katrin
K
Bohl
Department of Bioinformatics, Friedrich Schiller University Jena, Germany.|Research Group Theoretical Systems Biology, Friedrich Schiller University Jena, Germany.
Anja
0000-0001-8682-8308
A
Lück
Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.
Samay
S
Pande
Department of Bioinformatics, Friedrich Schiller University Jena, Germany.
Anja
A
Schröter
Research Group Theoretical Systems Biology, Friedrich Schiller University Jena, Germany.|Research Group Medical Systems Biology, Institute for Experimental Medicine, Christian-Albrechts-University Kiel, Germany.
Christoph
C
Kaleta
Department of Bioinformatics, Friedrich Schiller University Jena, Germany.
Stefan
0000-0003-0470-9802
S
Schuster
Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.|Department of Ecology and Evolution, School of Biology/Chemistry, Osnabrück University, Germany.
Christian
C
Kost
D000596:Amino Acids / Q000378:metabolism; D001419:Bacteria / Q000235:genetics* / Q000378:metabolism*; D019295:Computational Biology; D003198:Computer Simulation; D005838:Genotype; D059013:Microbial Consortia / Q000502:physiology*; D056265:Microbial Interactions / Q000502:physiology*
D000596:Amino Acids