Coral reefs hold far more than the life you can see. A study published in Nature says each coral species hosts its own microbial community, and many of those microbes have never been genetically described before.
The international research team, which included scientists from the University of Galway, found coral reefs are home to microbes that produce chemicals with potential uses in medicine and biotechnology.
Researchers examined microbiome samples from 99 coral reefs across 32 Pacific islands through the Tara Pacific consortium. They reconstructed the genomes of 645 microbial species, and more than 99 percent of them had never been genetically described before.
The study also found these coral-associated bacteria contain a wider range of biosynthetic gene clusters, the genetic instructions for making natural compounds, than has been recorded anywhere else in the ocean.
Dr Maggie Reddy of the Ryan Institute at the University of Galway said the findings showed how much remains unknown.
“When we compared our findings with microbes found on other reef species, it became clear how little we still know. Of more than 4,000 microbial species identified, only 10% have any genetic information available, and fewer than 1% of the species found only in the Tara Pacific samples have been studied at all. This shows a major gap in our understanding and underlines the need for much more biodiversity surveys, especially in under-studied regions.”
The researchers said coral reefs support about one third of all visible marine life, but much of their diversity exists at a microscopic level in the coral microbiome.
That microbiome includes bacteria, archaea, fungi, viruses and algae that live on and inside coral tissue. Together, these organisms form a tightly connected system known as the holobiont, which the University of Galway said is essential for coral survival and function.
The team said damage to coral reefs does not only affect visible marine life such as fish, sponges and seaweeds. It also means losing what the researchers described as a vast “molecular library” tied to the microbes that live within them.
Professor Olivier Thomas of the Ryan Institute said the reef microbiome compared strongly with long-used natural product sources.
“The biosynthetic potential of reef-building coral microbiomes rivalled or surpassed that of traditional natural product sources like sponges. Among the biosynthetically rich bacteria in the reef microbiome, we identified previously unknown microorganisms (e.g. Acidobacteriota) living with corals that produce new enzymes with exciting potential biotechnology uses.
“The research is a clear call to action to protect our coral reefs , not just because of their value as a unique ecosystem , but to preserve the unique chemical diversity poised to enable future scientific breakthroughs.”
The study brought together researchers from the Marine Biodiversity Lab at the Ryan Institute, led by Dr Maggie Reddy and Professor Olivier Thomas, along with collaborators from ETH Zurich.
The samples were collected during the Tara Pacific expedition between 2016 and 2018 across a region containing about 40 percent of the world’s coral reefs.
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