Distinct Crypt Spaces within the Squid Light Organ Promote Polyclonal V. fischeri Infections
Animal physiology hinges on mutualistic relationships with microbial symbionts, which are often acquired through horizontal transmission. The interaction between Euprymna scolopes, or the Hawaiian bobtail squid, and bioluminescent marine bacterium Vibrio fischeri provides a useful model for studying the acquisition of symbionts from hosts’ environments. While the relationship is monospecific in nature, polyclonal populations are found to be associated with adult squids’ specialized light organs. The physiological implications of harboring multiple V. fischeri strains is unknown; however, this study examines the contribution of intraspecific competition to the generation of such diversity. Our findings include physiological and genetic characterizations of FQ-A001, a strain isolated from an E. scolopes specimen collected in Oahu, HI. Compared to type strain ES114, FQ-A001 exhibits similar growth rates in rich media, but increased bioluminescence output and decreased motility rates. Although a majority of animals were singly colonized by FQ-A001 following exposure to a 1:1 mixed inoculum, ES114 and FQ-A001 were not able to co-colonize the crypts of those animals whose light organs contained both strains. This result differs from the co-colonization of these spaces observed in similar assays with single genotypes. The outcome of those experiments suggests that both the light organ’s architecture and competition between diverse strains play critical roles in the establishment of polyclonal infections. By further studying the competition between and comparing the gene content of various symbiotic strains, we will increase our understanding of the molecular mechanisms underlying the acquisition of horizontally-transmitted microbes by metazoan hosts.
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|Distinct Crypt Spaces within the Squid Light Organ Promote Polyclonal V. fischeri Infections
|Attribution-NonCommercial-NoDerivs 3.0 United States
|June 22, 2016
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