Coral dying from heat stress revived with probiotics in open sea first

Scientists have successfully revived coral dying from heat stress by applying probiotic and post-biotic treatments in the open sea for the first time.

Although probiotics have been shown to rehabilitate corals in South Florida and in aquariums, researchers tested whether microbial therapy would work in the Red Sea during a natural marine heatwave.

The study, published in the journal Cell Reports, was a success.”We urgently need to understand both the natural mechanisms that allow some corals to tolerate heat and how we can safely enhance those mechanisms,” said co-lead author Dr. Erika Santoro, a postdoctoral fellow at KAUST University in Saudi Arabia.

Corals host several beneficial bacteria that help them adapt to their environment. The aim of microbial therapy is to restore not just the corals themselves but also the microbiomes they sustain.

Probiotics are groups of living microbes obtained from healthy corals that may be applied to stressed corals. Post-biotics are inactivated probiotics and/or their bioactive components.”The possibility of using post-biotics is particularly exciting… potentially offer practical advantages, such as longer shelf life, easier storage and transportation, and reduced production costs,” Dr. Santoro explained.

The team treated Valid Acropora coral in the central Red Sea during a heatwave in 2022, when daily average seawater temperatures ranged from 30.9°C to 31.9°C.

Throughout the 15-day field experiment, researchers isolated beneficial bacterial strains from Red Sea corals to create two probiotic treatments and their post-biotic counterparts.

They measured health by evaluating colour — white or bleached hues indicate poor health — and the photosynthetic efficiency of algae living inside them.

After 15 days, one probiotic and one post-biotic formula had “significantly improved” coral health.”When an innovative idea like this actually works — particularly under field conditions — we are positively surprised,” said Santoro.

Genetic tests showed post-biotic-treated corals had an increase in Cobetia, a bacteria that helps corals tolerate heat stress.”The most exciting takeaway is that this study opens a new avenue for coral microbial therapies,” Santoro said.