For natural selection to operate there must exist heritable variation among individuals that affects their survival and reproduction. Among free-living microbes, where differences in growth rates largely define selection intensities, competitive exclusion is common. However, among surface attached communities, these dynamics become less predictable. If extreme circumstances were to dictate that a surface population is immortal and all offspring must emigrate, the offspring would be unable to contribute to the composition of the population. Meanwhile, the immortals, regardless of reproductive capacity, would remain unchanged in relative abundance. The normal cycle of birth, death, and competitive exclusion would be broken. We tested whether conditions required to set up this idealized scenario can be approximated in a microbial biofilm. Using two differentially-reproducing strains of Shewanella oneidensis grown on an anode as the sole terminal electron acceptor – a system in which metabolism is obligately tied to surface attachment – we found that selection against a slow-growing competitor is drastically reduced. This work furthers understanding of natural selection dynamics in sessile microbial communities, and provides a framework for designing stable microbial communities for industrial and experimental applications.
Bibliographical noteFunding Information:
We thank Aunica Kane and Evan Brutinel for the strain constructs, and Komal Joshi and Geoff Harms for the design and construction of the batch-fed bioreactors. We thank Trinity Hamilton and Anna Bennett for critical readings and constructive advice during manuscript preparation. We thank the BioTechnology Institute and Biocatalysis Initiative at the University of Minnesota for initial funding for this project. This work was funded in part by the Office of Naval Research (Awards N00014-12-1-0309 and N00014-13-1-0552 to JAG).
© 2021, The Author(s).
PubMed: MeSH publication types
- Journal Article
- Research Support, U.S. Gov't, Non-P.H.S.
- Research Support, Non-U.S. Gov't