Abundant ketone isolated from oily Plakortis sponge demonstrates antifouling properties

Trait-Based Comparison of Coral and Sponge Microbiomes

Corals and sponges harbor diverse microbial communities that are integral to the functioning of the host. While the taxonomic diversity of their microbiomes has been well-established for corals and sponges, their functional roles are less well-understood. It is unclear if the similarities of symbiosis in an invertebrate host would result in functionally similar microbiomes, or if differences in host phylogeny and environmentally driven microhabitats within each host would shape functionally distinct communities. Here we addressed this question, using metatranscriptomic and 16S rRNA gene profiling techniques to compare the microbiomes of two host organisms from different phyla. Our results indicate functional similarity in carbon, nitrogen, and sulfur assimilation, and aerobic nitrogen cycling. Additionally, there were few statistical differences in pathway coverage or abundance between the two hosts. For example, we observed higher coverage of phosphonate and siderophore metabolic pathways in the star coral, Montastraea cavernosa, while there was higher coverage of chloroalkane metabolism in the giant barrel sponge, Xestospongia muta. Higher abundance of genes associated with carbon fixation pathways was also observed in M. cavernosa, while in X. muta there was higher abundance of fatty acid metabolic pathways. Metagenomic predictions based on 16S rRNA gene profiling analysis were similar, and there was high correlation between the metatranscriptome and metagenome predictions for both hosts. Our results highlight several metabolic pathways that exhibit functional similarity in these coral and sponge microbiomes despite the taxonomic differences between the two microbiomes, as well as potential specialization of some microbially based metabolism within each host.

Sponge chemical diversity: from biosynthetic pathways to ecological roles

Since more than 50 years, sponges have raised the interest of natural product chemists due to the presence of structurally original secondary metabolites. While the main objective were first to discover new drugs from the Sea, a large number of interrogations arose along with the isolation and structure elucidations of a wide array of original architectures and new families of natural products not found in the terrestrial environment. In this chapter, we focus on the results obtained during this period on the following questions. A preliminary but still unresolved issue to be addressed will be linked to the role of the microbiota into the biosynthesis of these low-weight compounds. Our knowledge on the biosynthetic pathways leading to plant secondary metabolites is now well established, and this background will influence our comprehension of the biosynthetic events occurring in a sponge. But is the level of similarity between both metabolisms so important? We clearly need more experimental data to better assess this issue. This question is of fundamental interest because sponges have a long evolutionary history, and this will allow a better understanding on the transfer of the genetic information corresponding to the biosynthesis of secondary metabolites. After the how, the why! The question of the ecological role of these metabolites is also of high importance first not only because they can serve as synapomorphic characters but also because they may represent chemical cues in the water environment. Even if most of these compounds are considered as defensive weapons for these sessile invertebrates, they may also be linked to physiological characters as the reproduction. Finally, a metabolomic approach can appear as a complementary tool to give additional information on the sponge fitness. All the new developments in molecular biology and bioanalytical tools will open the way for a better comprehension on the complex field of sponge secondary metabolites.

Microscopic anatomy and pigment characterization of coral-encrusting black sponge with cyanobacterial symbiont, Terpios hoshinota

Terpios hoshinota is a black-colored sponge encrusting both live and dead corals. On examination, we determined that in the mesohyl, unicellular cyanobacteria were distributed extracellularly in dense populations; roughly half of the area in the histological sections was occupied by the cyanobacterial cells in the mesohyl of the inner zone. Pigment extraction tests of whole sponges and microspectrophotometrical analysis of cyanobacterial symbionts showed that the black coloration of the sponge is attributable to extremely densely packed cyanobacteria expressing R-phycoerythrin. Spermatic follicles were found in the mesohyl of specimens collected in summer, indicating seasonal reproduction, which is likely to play a crucial role in long-distance dispersal. We also found a possible oocyte that did not contain cyanobacteria in the ooplasm.