M.J. Neave, C.T. Michell, A. Apprill, C.R. Voolstra
Scientific Reports, 7, 40579, (2017)
Endozoicomonas bacteria are globally distributed and often
abundantly associated with diverse marine hosts including reef-building
corals, yet their function remains unknown. In this study we generated
novel Endozoicomonas genomes from single cells and metagenomes obtained directly from the corals Stylophora pistillata, Pocillopora verrucosa, and Acropora humilis.
We then compared these culture-independent genomes to existing genomes
of bacterial isolates acquired from a sponge, sea slug, and coral to
examine the functional landscape of this enigmatic genus. Sequencing and
analysis of single cells and metagenomes resulted in four novel genomes
with 60–76% and 81–90% genome completeness, respectively. These data
also confirmed that Endozoicomonas genomes are large and are not
streamlined for an obligate endosymbiotic lifestyle, implying that they
have free-living stages. All genomes show an enrichment of genes
associated with carbon sugar transport and utilization and protein
secretion, potentially indicating that Endozoicomonas contribute
to the cycling of carbohydrates and the provision of proteins to their
respective hosts. Importantly, besides these commonalities, the genomes
showed evidence for differential functional specificity and
diversification, including genes for the production of amino acids.
Given this metabolic diversity of Endozoicomonas we propose that different genotypes play disparate roles and have diversified in concert with their hosts.