Spatial structure favors microbial coexistence except when slower mediator diffusion weakens interactions

Abstract
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Abstract

Microbes often exist in spatially structured environments and many of their interactions are mediated through diffusible metabolites. How does such a context affect microbial coexistence? To address this question, we use a model in which the spatial distributions of species and diffusible interaction mediators are explicitly included. We simulate the enrichment process, examining how microbial species spatially reorganize and how eventually a subset of them coexist. In our model we find that slower motility of cells promotes coexistence by allowing species to co-localize with their facilitators and avoid their inhibitors. We additionally find that a spatially structured environment is more influential when species mostly facilitate each other, rather than when they are mostly competing. More coexistence is observed when species produce many mediators and consume some (not many or few) mediators, and when overall consumption and production rates are balanced. Interestingly, coexistence appears to be disfavored when mediators are diffusing slowly because that leads to weaker interaction strengths. Overall, our results offer new insights into how production, consumption, motility, and diffusion intersect to determine microbial coexistence in a spatially structured environment.

Data availability

Codes used to generate the data in this study are shared on GitHub at https://github.com/bmomeni/spatial-coexistence.

Article and author information

Author details

Alexander Lobanov

Biology Department, Boston College, Chestnut Hill, United States

Competing interests
No competing interests declared.
Samantha Dyckman

Biology Department, Boston College, Chestnut Hill, United States

Competing interests
No competing interests declared.
Helen Kurkjian

Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland

Competing interests
No competing interests declared.
Babak Momeni

Biology Department, Boston College, Chestnut Hill, United States

For correspondence
momeni@bc.edu

Competing interests
Babak Momeni, Reviewing editor, eLife.

"This ORCID iD identifies the author of this article:" 0000-0003-1271-5196

Funding

Richard and Susan Smith Family Foundation

Samantha Dyckman
Helen Kurkjian
Babak Momeni

Boston College (URF)

Alexander Lobanov

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.