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Free keywords:
host-microbe; Cnidaria; phylosymbiotic; core microbiota; holobiont
Abstract:
Animals are colonized by coevolved bacterial communities, which
contribute to the host’s health. This commensal microbiota is often
highly specific to its host-species, inferring strong selective pressures
on the associated microbes. Several factors, including diet,
mucus composition, and the immune system have been proposed
as putative determinants of host-associated bacterial communities.
Here we report that species-specific antimicrobial peptides
account for different bacterial communities associated with closely
related species of the cnidarian Hydra. Gene family extensions for
potent antimicrobial peptides, the arminins, were detected in four
Hydra species, with each species possessing a unique composition
and expression profile of arminins. For functional analysis, we inoculated
arminin-deficient and control polyps with bacterial consortia
characteristic for different Hydra species and compared their
selective preferences by 454 pyrosequencing of the bacterial
microbiota. In contrast to control polyps, arminin-deficient polyps
displayed decreased potential to select for bacterial communities
resembling their native microbiota. This finding indicates that species-
specific antimicrobial peptides shape species-specific bacterial
associations.
