December 11, 2023

Researchers investigating the coral microbiome of Australia’s Great Barrier Reef have discovered two groups of co-existing bacteria. And, for the first time, they found that one of them is a close relative of the bacterium that causes chlamydia infection in humans. The discovery provides more information about the health of coral reefs and may help address coral bleaching.

The rich biodiversity of coral reefs makes them one of the most important ecosystems on Earth. Corals depend on a variety of microorganisms for their survival, including bacteria, fungi and viruses. Located off the northeastern coast of Australia, the Great Barrier Reef is the largest and most famous coral reef system in the world, comprising more than 2,900 individual reefs and 900 islands, covering an area of ​​approximately 132,973 square miles (344,400 square kilometers).

Bacteria play a key role in protecting corals from pathogens, cycling nutrients, and producing vitamins and essential amino acids. They usually reside in the mucus and skeleton of corals, and rarely in tissues. When bacteria are observed in tissues, they form large, dense clusters called cell-associated microbial aggregates (CAMAs).

Researchers from the University of Melbourne, Australia’s Townsville Institute of Marine Science and the University of Vienna have discovered two types of CAMA in the tissue of Pocillopora acinus corals in the Great Barrier Reef.

First, belong to Endophytes genus, known to be widespread in corals. This bacterium is widely believed to be beneficial to corals due to its ability to produce B vitamins and antimicrobial compounds.

The second bacterium was unexpected.It was found from the genus Chlamydiales, which includes the bacteria that causes chlamydia, a sexually transmitted infection, in humans.this is the first time Chlamydiales Found in corals.

“We are with Chlamydiales Experts Dr. Astrid Collingro and Prof. Matthias Horn from the University of Vienna discovered that these bacteria steal nutrients and energy from their hosts to survive,” says Justin Maire, first author of the study.

Using a combination of imaging techniques, microdissection and genome sequencing, the researchers found that CAMA is located in P. Acute coral and that Endophytes and Chlamydiales Occurs in a different but adjacent CAMA.

discovery of novels Chlamydiales and it with Endophytes Advancing our understanding of the complex coral microbiome and reef health.

“This bacterium has the potential to obtain nutrients and energy from other coral-associated bacteria, and for those of us working to understand coral biology, the possibility of interactions between bacteria living within coral tissue is very exciting,” Maire said .

Global warming has triggered marine heatwaves that have led to coral bleaching on the Great Barrier Reef and other reefs around the world. When the reef’s seawater gets too warm for too long, the coral becomes stressed and expels the colorful algae (zooxanthellae) that live within its tissues, leaving behind a white skeleton. It may take decades for coral reefs to recover from bleaching, if they recover at all.

The researchers hope their findings will contribute to the use of probiotics to tackle coral bleaching on the Great Barrier Reef.

“One area of ​​focus in my lab is the development of bacterial probiotics for corals to help increase their resistance to heat stress and survival in a warming climate,” said study co-author Madeleine van Oppen. “We don’t know much about the function of coral-associated bacteria, and this new study will help us figure out whether probiotics are a viable solution, and whether bacteria Endophytes Best for the job. “

The study was published in the journal scientific progress.

source: University of Melbourne