Archaea, Bacteria, and Algal Plastids Associated with the Reef-Building Corals Siderastrea stellata and Mussismilia hispida from Búzios, South Atlantic Ocean, Brazil

Abstract

Reef-building corals may be seen as holobiont organisms, presenting diverse associated microbial communities. Best known is the symbiotic relationship with zooxanthellae, but Archaea, Bacteria, fungi, viruses, and algal plastids are also abundant. Until now, there is little information concerning microbial communities associated with Brazilian corals. The present study aims to describe the diversity of Archaea, Bacteria, and eukaryotic algal plastid communities associated with two sympatric species, Siderastrea stellata and Mussismilia hispida, from Southeastern Brazil, using 16S rRNA gene libraries. Since corals present a high number of other associated invertebrates, coral barcoding (COI) was performed to confirm the exclusive occurrence of coral DNA in our samples. Our analysis yielded 354 distinct microbial OTUs, represented mainly by novel phylotypes. Richness (Chao1 and ACE) and diversity (H') estimations of the microbial communities associated with both species were high and comparable to other studies. Rarefaction analyses showed that microbial diversity of S. stellata is higher than that of M. hispida. Libshuff comparative analyses showed that the highest microbial community similarity between the two coral species occurred in the bacterial libraries, while archaeal and plastidial communities were significantly different. Crenarchaeota dominated archaeal communities, while Proteobacteria was the most abundant bacterial phylum, dominated by alpha-Proteobacteria. Plastids were also represented by novel phylotypes and did not match with any 16S rRNA sequences of Cyanobacteria and zooxanthellae from GenBank. Our data improves the pool of available information on Brazilian coral microbes and shows corals as sources of diverse prokaryotic and picoeukaryotic communities.

Archaea in Natural and Impacted Brazilian Environments

“…In healthy Siderastrea stellata corals and different sponges, the archaeal diversity was higher, but the majority of DNA sequences were classified as uncharacterized crenarchaeotes, while in Mussismilia hispida , an endangered coral species, and also in some sponge species, sequences related to N. maritimus and C. symbiosum were detected. These findings are in accordance with works performed with Australian corals [31, 32]. On the other hand, corals reefs from unprotected areas revealed a lower diversity and abundance of Archaea than that of the healthier ones [33, 34].…”

“…Archaeal communities were also studied in sponges and corals of protected and unprotected marine areas [28, 31–34]. In healthy Siderastrea stellata corals and different sponges, the archaeal diversity was higher, but the majority of DNA sequences were classified as uncharacterized crenarchaeotes, while in Mussismilia hispida , an endangered coral species, and also in some sponge species, sequences related to N. maritimus and C. symbiosum were detected.…”

Spatial and Species Variations in Bacterial Communities Associated with Corals from the Red Sea as Revealed by Pyrosequencing

“…Altogether, 21 bacterial phyla were detected in our corals, many of which have been reported in corals around the world, ranging from tropical and subtropical to Antarctic environments (43,52,65,80,81,82). We recovered all of the major phyla previously reported in corals, including Proteobacteria (particularly Gammaproteobacteria), Actinobacteria, Cyanobacteria, and Firmicutes.…”

Habitat-specific environmental conditions primarily control the microbiomes of the coral Seriatopora hystrix

“…Less is known about the role of archaea associated with reef-building corals. Archaea associated with the coral tissues have been found to occur at varying cell densities (Wegley et al, 2004), and with varied levels of diversity relative to bacterial communities (Wegley et al, 2004Siboni et al, 2008;Lins-de-Barros et al, 2010;Littman et al, 2011), and in some cases have been found to be absent from coral colony tissues altogether (Yakimov et al, 2006;Hansson et al, 2009). Coral-associated archaeal communities are also independent of those in the water column, but in contrast to bacteria they are fairly cosmopolitan, displaying no evidence of species specificity.…”