Host: Professor Raquel Peixoto
Octocorals (Octocorallia, Anthozoa) are a widespread group of coral and an integral part of benthic marine ecosystems. They increase habitat complexity and biodiversity and play key roles in coastal food chains. Octocorals are found in association with various microorganisms, including micro-eukaryotes, prokaryotes, and viruses. In Mediterranean and North-East Atlanticoctocoral populations, heat waves and infectious diseases led to significant mortalities. In other parts of the world, however, octocorals continue to thrive. It is yet to be determined why some octocorals resist while others are affected by climate change scenarios — but their associated microbiome could play a key role in their response.
Our research on temperate octocorals showed that their microbiome is distinct from the environmental surroundings, host genus-specific, and undergoes complex structural changes in the transition to the dysbiosis state. To shed light on metabolic potential of octocoral symbionts, we reconstructed>65 high-quality metagenome-assembled genomes (MAGs), spanning 30prokaryotic species. Symbionts of healthy octocorals were affiliated with Endozoicomonadaceae, Candidatus Thioglobaceae, and Metamycoplasmataceae, among others. Phylogenomics showed that the Endozoicomonadaceae MAGs represent a novel genus unique to temperate octocorals, denoted Candidatus Gorgonimonas. Their genomes revealed metabolic capacities to thrive under suboxic conditions and high numbers of genes related with host colonization and aggregation. All Candidatus Gorgonimonas symbionts harboured chitinase and chitin-binging protein-encoding genes, indicating that they can hydrolyze the most abundant polysaccharide in the ocean. This indicates a thus-far unanticipated role for Endozoicomonadaceae in the processing of chitin which is a major component of the natural zoo- and phytoplankton feed of octocorals. Other symbionts possessed genes to assimilate smaller chitin-oligosaccharides resulting from chitin breakdown, suggesting possibilities for cross-feeding and a role for the coral microbiome in overall chitin turnover. Since Candidatus Gorgonimonas symbionts remain unculturable, we now employ gene synthesis and heterologous expression to harness and characterize their enzymes. Indeed, chitinases and chitin degradation processes holds excellent opportunities for upcycling of sea-food waste as chitin-derived added-value products find applications in the pharmaceutical sector, biomedicine, food industry, and agriculture.
Over the past years, we also established an extensive culture collection of > 1000 marine sponge and octocoral‐associated bacteria, revealing a versatile secondary metabolite biosynthesis potential and antimicrobial activities against human and aquaculture pathogens. The genus Aquimarina is particularly attractive, producing the novel polyketide cuniculene and the peptide antibiotic saquimarins. Metabolomics and genomics data suggest an even greater natural product biosynthesis capacity, holding promise for a future sustainable production of new marine drug leads.
Tina Keller-Costa is a Research Scientist and Invited Assistant Professor at Instituto Superior Técnico at University of Lisbon, Portugal. She studied Biology at the Friedrich-Schiller University of Jena, Germany and wrote her MSc thesis on the microbiome of freshwater sponges at the Rijksunversiteit Groningen, The Netherlands. She holds a PhD degree in Biology from the University of Évora and the Centre of Marine Sciences, Faro, Portugal where she identified the male pheromone of tilapia (fish) in collaboration with the Max Planck Institute for Chemical Ecology, Jena, Germany. Tina’s current research focuses on the structure, function, and biotechnological potential of marine and octocoral microbiomes to foster a sustainable blue bioeconomy and ocean health. She is involved in Portugal’s ‘Blue Bioeconomy Pact’ funded by the EU through Portugal’s Recovery and Resilience Plan. Consisting of >80 national entities, including53 companies, this project aims to develop the sustainable use of marine resources across multiple sectors such as aquaculture, fisheries, food, feed, textiles, biomaterials, and human health. Tina authored/co-authored 38scientific publications in a range of journals, including Current Biology, Microbiome, Nature Microbiology, Annual Reviews of Animal Biosciences, Science of the total Environment, and >80 conference contributions. She serves as review editor for Frontiers in Microbiology and guest editor for Marine Drugs.