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Msh Pilus Mutations Increase the Ability of a Free-Living Bacterium to Colonize a Piscine Host
Version 1
: Received: 14 December 2020 / Approved: 15 December 2020 / Online: 15 December 2020 (16:34:25 CET)
A peer-reviewed article of this Preprint also exists.
Lebov, J.F.; Bohannan, B.J.M. Msh Pilus Mutations Increase the Ability of a Free-Living Bacterium to Colonize a Piscine Host. Genes 2021, 12, 127. Lebov, J.F.; Bohannan, B.J.M. Msh Pilus Mutations Increase the Ability of a Free-Living Bacterium to Colonize a Piscine Host. Genes 2021, 12, 127.
Abstract
Symbioses between animals and bacteria are ubiquitous. To better understand these relationships, it is essential to unravel how bacteria evolve to colonize hosts. Previously, we serially passaged the free-living bacterium, Shewanella oneidensis, through the digestive tracts of germ-free larval zebrafish (Danio rerio) to uncover the evolutionary changes involved in the initiation of a novel symbiosis with a vertebrate host. After 20 passages, we discovered an adaptive missense mutation in the mshL gene of the msh pilus operon, which improved host colonization, increased swimming motility, and reduced surface adhesion. In the present study, we have determined that this mutation was a loss-of-function mutation and found that it improved zebrafish colonization by augmenting S. oneidensis representation in the water column outside larvae through a reduced association with environmental surfaces. Additionally, we found that strains containing the mshL mutation were able to immigrate into host digestive tracts at higher rates per capita. However, mutant and evolved strains exhibited no evidence of a competitive advantage after colonizing hosts. Our results demonstrate that bacterial behaviors outside the host can play a dominant role in facilitating the onset of novel host associations.
Keywords
Host-microbe; Zebrafish; Shewanella; Symbiosis; Microbial evolution; Msh pilus; Adaptation; Biofilms; Fitness; Colonization
Subject
Biology and Life Sciences, Biochemistry and Molecular Biology
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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