BioTechnology Institute, University of Minnesota, St Paul, MN, USA.
Department of Plant and Microbial Biology, University of Minnesota, St Paul, MN, USA.
Commun Biol. 2021 May 6;4(1):536. doi: 10.1038/s42003-021-02040-1.
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.
为了让自然选择起作用，个体之间必须存在可遗传的变异，这些变异会影响它们的生存和繁殖。在自由生活的微生物中，生长速度的差异在很大程度上决定了选择的强度，竞争排斥是很常见的。然而，在表面附着的群落中，这些动态变得不太可预测。如果极端情况决定了表面种群是不朽的，所有后代都必须迁移，那么后代将无法为种群的组成做出贡献。与此同时，无论繁殖能力如何，不朽者的相对丰度仍将保持不变。正常的出生、死亡和竞争排斥的循环将被打破。我们测试了在微生物生物膜中是否可以近似设置这种理想化场景所需的条件。我们使用两种不同繁殖能力的希瓦氏菌（Shewanella oneidensis）在阳极上生长作为唯一的末端电子受体——在这种系统中，新陈代谢必须与表面附着相联系——我们发现，对生长缓慢的竞争者的选择大大减少。这项工作增进了对附着微生物群落中自然选择动态的理解，并为设计用于工业和实验应用的稳定微生物群落提供了框架。
