Sponge-Associated Bacteria Are Strictly Maintained in Two Closely Related but Geographically Distant Sponge Hosts

Abstract

The giant barrel sponges Xestospongia muta and Xestospongia testudinaria are ubiquitous in tropical reefs of the Atlantic and Pacific Oceans, respectively. They are key species in their respective environments and are hosts to diverse assemblages of bacteria. These two closely related sponges from different oceans provide a unique opportunity to examine the evolution of sponge-associated bacterial communities. Mitochondrial cytochrome oxidase subunit I gene sequences from X. muta and X. testudinaria showed little divergence between the two species. A detailed analysis of the bacterial communities associated with these sponges, comprising over 900 full-length 16S rRNA gene sequences, revealed remarkable similarity in the bacterial communities of the two species. Both sponge-associated communities include sequences found only in the two Xestospongia species, as well as sequences found also in other sponge species and are dominated by three bacterial groups, Chloroflexi, Acidobacteria, and Actinobacteria. While these groups consistently dominate the bacterial communities revealed by 16S rRNA gene-based analysis of sponge-associated bacteria, the depth of sequencing undertaken in this study revealed clades of bacteria specifically associated with each of the two Xestospongia species, and also with the genus Xestospongia, that have not been found associated with other sponge species or other ecosystems. This study, comparing the bacterial communities associated with closely related but geographically distant sponge hosts, gives new insight into the intimate relationships between marine sponges and some of their bacterial symbionts.Marine sponges (phylum Porifera) are ancient metazoans with a fossil record dating back over 600 million years, but the duration of the sponge-bacterium association is less well documented. Sponges actively pump seawater through pores and channels to obtain food consisting mainly of microbes filtered from the surrounding seawater, but they have no true organs or circulatory, nervous, or digestive systems. Bacterial symbionts may play roles in digestion, waste removal, and chemical defense for the sponge host (38). We use the terms "symbiont" and "symbiosis" in the same sense as Taylor et al. (38) and consistent with the original definition of de Bary to refer to two or more organisms consistently found living together for a long period without any implication that the organisms benefit or harm each other.Many sponges contain chemical compounds with bioactive properties, several of which are promising as pharmaceutical leads, and sponge-associated microorganisms are of interest due to their potential role in producing some of these compounds (10). Studies of the bacteria associated with marine sponges have revealed novel bacterial groups, such as the candidate phylum "Poribacteria" (6, 16), as well as ubiquitous symbionts found in many different sponges, including the NW001-like Alphaproteobacteria (4, 46). Sponge-microbe associations provide a model for studying ancient, complex symbioses ...

Diversity and abundance of ammonia-oxidizing Archaea and Bacteria in tropical and cold-water coral reef sponges

“…And AOB sequences retrieved from N. nodastrella in Cluster 3 group with sequences from Dysidea avara from the Mediterranean. Such diverse distribution of bacterial communities has also been reported in earlier studies, with geographically distant sponges showing similar sponge-associated Bacteria (Montalvo & Hill 2011, Yang et al 2011, Ribes et al 2012. Two of the wellsupported clusters (Clusters 1 and 2) contained mainly sequences from sponges and sediment, while Cluster 6 contained only sequences from sponges and water.…”

The HMA-LMA Dichotomy Revisited: an Electron Microscopical Survey of 56 Sponge Species

“…Additional and distinct patterns might be revealed on lower taxonomic levels given a more representative taxonomic sampling. It is noteworthy, however, that the HMA/LMA characteristics are conserved in closely related species over time and space when collected from different geographic regions (Wilkinson, 1978;Montalvo and Hill, 2011).…”

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.…”