Rethinking the Coral Microbiome: Simplicity Exists within a Diverse Microbial Biosphere

Abstract

We propose that the coral holobiont should be conceptualized as a diverse transient microbial community that is responsive to the surrounding environment and encompasses a simple, redundant, resident microbiome and a small conserved core microbiome. Most importantly, we show that the coral microbiome is comparable to the microbiomes of other organisms studied thus far. Accurately characterizing the coral-microbe interactions provides an important baseline from which the functional roles and the functional niches within which microbes reside can be deciphered.

Uncovering the core microbiome and distributions of palmerolide inSynoicum adareanumacross the Anvers Island archipelago, Antarctica

“…Corals also have a small set of conserved, core bacteria across ocean habitats and basins (e.g. 19, 20), in which the structure has been proposed to occur at the level of the individual (21). Ascidians have been less well studied regarding the persistence of host-microbiome association, though there is supporting evidence that ascidian-associated microbiota tend to have species specificity (22) and that their composition is likely linked to secondary metabolite production (8).…”

Characterizing the ecology of coral reef microorganisms across different scales within the Caribbean

“…For example, P. astreoides' ecosphere bacterial and archaeal communities sampled in Cuba were more similar to reef-depth seawater microbial communities compared to ecosphere communities sampled surrounding other Caribbean coral species including P. astreoides, Orbicella faveolata, Montastrea cavernosa, Pseudodiploria strigosa, and Acropora cervicornis (Weber et al 2019). The second potential explanation is that associations between Gammaproteobacteria and P. astreoides could be sitespecific and depend on local environmental conditions and/or on the health state of the coral colony, similar to observations that have been made about common coral-associated microorganisms (Hernandez-Agreda et al 2018;Weber et al 2019). For instance, the coral colonies sampled within Cuba by Weber et al (2019) were located on more continuous reef structure with higher coral cover compared to the corals sampled in this study, which were located adjacent to sand patches.…”

“…Coral-associated microbial communities are quite taxonomically diverse (Knowlton and Rohwer 2003;Sunagawa et al 2010), but there is a large effort to understand which taxa are transient and influenced by local environmental conditions compared to taxa that are members of the core microbial community (Ainsworth et al 2015;Hernandez-Agreda et al 2018). This is because microbial taxa with core membership are more likely to be microbial symbionts of corals, playing important roles in coral health and growth.…”

“…Based on the lifestyle and genome of the first described species in this candidate genus, "Candidatus Amoebophilus asiaticus", "Ca Amoebophilus" taxa within coral tissue could be associated with other single-celled eukaryotic organisms within corals (Horn et al 2001;Schmitz-Esser et al 2010;. Other putative bacterial symbionts have been suggested for corals (Ainsworth et al 2015;Hernandez-Agreda et al 2018;Pollock et al 2018), but very few studies have definitively investigated the interactions of these bacteria with coral hosts. However, the work conducted by Pollock et al (2018) and Huggett and Apprill (2019) provide a solid platform for future coral-microbial symbioses research.…”

Peer Review #2 of "Disentangling the effect of host-genotype and environment on the microbiome of the coral Acropora tenuis (v0.1)"

“…This ubiquitous strain likely represents a stable and consistent member of the resident Endozoicomonas community. A stable core is often described as a key feature of a symbiotic coral microbiome (Ainsworth et al 2015;Hernandez-Agreda et al 2017), and despite being ubiquitously persistent between conspecific corals, the core characteristically only comprises a few members of the whole microbiome (Hernandez-Agreda et al 2018).…”