Coral-Associated Bacterial Diversity Is Conserved across Two Deep-Sea Anthothela Species

Abstract

Cold-water corals, similar to tropical corals, contain diverse and complex microbial assemblages. These bacteria provide essential biological functions within coral holobionts, facilitating increased nutrient utilization and production of antimicrobial compounds. To date, few cold-water octocoral species have been analyzed to explore the diversity and abundance of their microbial associates. For this study, 23 samples of the family Anthothelidae were collected from Norfolk (n = 12) and Baltimore Canyons (n = 11) from the western Atlantic in August 2012 and May 2013. Genetic testing found that these samples comprised two Anthothela species (Anthothela grandiflora and Anthothela sp.) and Alcyonium grandiflorum. DNA was extracted and sequenced with primers targeting the V4–V5 variable region of the 16S rRNA gene using 454 pyrosequencing with GS FLX Titanium chemistry. Results demonstrated that the coral host was the primary driver of bacterial community composition. Al. grandiflorum, dominated by Alteromonadales and Pirellulales had much higher species richness, and a distinct bacterial community compared to Anthothela samples. Anthothela species (A. grandiflora and Anthothela sp.) had very similar bacterial communities, dominated by Oceanospirillales and Spirochaetes. Additional analysis of core-conserved bacteria at 90% sample coverage revealed genus level conservation across Anthothela samples. This core included unclassified Oceanospirillales, Kiloniellales, Campylobacterales, and genus Spirochaeta. Members of this core were previously recognized for their functional capabilities in nitrogen cycling and suggest the possibility of a nearly complete nitrogen cycle within Anthothela species. Overall, many of the bacterial associates identified in this study have the potential to contribute to the acquisition and cycling of nutrients within the coral holobiont.

Resilience of the prokaryotic microbial community of Acropora digitifera to elevated temperature

“…In contrast to observations from thermal stress experiments in the coral Acropora muricata (Lee et al., ), where total Gammaproteobacteria decreased while Verrucomicrobiaceae and total Alphaproteobacteria increased, we observed a general decrease in the relative abundance of Alphaproteobacteria OTUs and an increase in total Gammaproteobacteria OTUs in A. digitifera . Members of Alphaproteobacteria , specifically order Rhodobacterales, are ubiquitous in coral reef ecosystems (Lawler et al., ) and comprise one of the dominant orders of bacteria in corals (Kemp et al., ) while order Rhizobiales are potentially Symbiodinium ‐associated taxa (Ainsworth et al., ). It has been shown that Alphaproteobacteria are typically associated with reefs that have higher coral cover while Gammaproteobacteria and Flavobacteriales are abundant in more degraded algae‐dominated reefs (Kelly et al., ).…”

Characterization of the Gut Microbiota of the Antarctic Heart Urchin (Spatangoida) Abatus agassizii

“…The gut tissue of A. agassizii was dominated by Spirochaetia, mostly represented by the genus Spirochaeta which was prevalent in all of the samples and accounted for as much as 80% relative abundance of the class. Spirochaetes are motile freeliving, facultative/obligate anaerobes (Leschine et al, 2006), associated with numerous marine invertebrates, among others, corals (Lawler et al, 2016;Van De Water et al, 2016), sponges (Matcher et al, 2017;Kellogg, 2019), sea stars (Jackson et al, 2018), and at the body surface of the regular sea urchin species Tripneustes gratilla (<15% relative abundance) (Brink et al, 2019). Such a prevalence inside the gut of a sea urchin has never been described and suggests a specific interaction between Spirochaeta and the Abatus host.…”

Laboratory-Cultured Strains of the Sea Anemone Exaiptasia Reveal Distinct Bacterial Communities

“…studies (e.g., Littman et al, 2009;Pantos et al, 2015;Roder et al, 2015) have suggested that geographic location and environmental settings can determine the holobiont microbiome, whereas others (e.g., Hentschel et al, 2002;Fraune and Bosch, 2007;Montalvo and Hill, 2011;Lawler et al, 2016) have shown that bacterial communities are species-specific associations conserved over time and space. Moreover, coevolution of bacteria and coral has been proposed (Thompson et al, 2015), as it was demonstrated for Endozoicomonas symbionts in corals with contrasting life-history traits and across global scales (Bayer et al, 2013;Neave et al, 2016Neave et al, , 2017.…”