Amoxicillin treatment of coral. Photo: Cited scientific paper

Back in 2021, researchers found that amoxicillin had a 95% success rate at healing lesions from stony coral tissue loss disease (SCTLD). Traditional antibiotic treatment could cause resistant pathogenic bacteria though, so scientists from the Smithsonian’s National Museum of Natural History have looked into the use of probiotics instead.

Why do corals need antibiotics?

Since its discovery in Florida in 2014, cases of SCTLD have been confirmed in at least 20 countries. The cause is not yet known, but once a coral is infected, its colony of polyps can die within weeks. This makes SCTLD treatment, prevention and cure a top priority for coral reef scientists.

The Research

Whilst trying to figure out how SCTLD is spread, Valerie Paul, head scientist at the Smithsonian Marine Station at Fort Pierce, and a team of researchers, discovered that some fragments of great star coral (Montastraea cavernosa) quickly developed lesions and died, but other pieces never got sick at all. This made them think that perhaps there were microorganisms protecting some of the corals.

The Discovery

The team tested the 222 bacterial strains that they collected from the disease-resistant corals and found that 83 strains had some antimicrobial activity. One in particular, stopped or slowed the progression of the disease in 68.2% of infected coral fragments AND prevented the sickness from spreading in all their transmission experiments. This is something antibiotics are unable to do.

So what?

The potential of this newly identified probiotic to help Florida’s corals without the danger of accidentally creating antibiotic-resistant bacteria is great news for those racing the clock to help save coral reefs.

To find out more:

Assessing the effectiveness of two intervention methods for stony coral tissue loss disease on Montastraea cavernosa by Erin N. Shilling, Ian R. Combs and Joshua D. Voss, 21 April 2021, Scientific Reports.

Chemical and genomic characterization of a potential probiotic treatment for stony coral tissue loss disease by Blake Ushijima, Sarath P. Gunasekera, Julie L. Meyer, Jessica Tittl, Kelly A. Pitts, Sharon Thompson, Jennifer M. Sneed, Yousong Ding, Manyun Chen, L. Jay Houk, Greta S. Aeby, Claudia C. Häse and Valerie J. Paul, 6 April 2023, Communications Biology.