Corals Survive the Heat With Help From Probiotic Bacteria

KAUST researchers are exploring the use of probiotic bacteria to boost the survival of corals after bleaching events.
Credit: © 2021 KAUST; Morgan Bennett Smith

Treating corals with a probiotic cocktail of beneficial bacteria increases survival after a bleaching event, according to new research. This approach could be administered in advance of a predicted heatwave to help corals recover from high sea temperatures.

Climate change is increasing the temperatures of the oceans, which disrupts the relationship between corals and their symbiotic photosynthetic algae and causes corals to bleach, in some cases eventually leading to their death. KAUST researchers have proposed that manipulating the coral microbiome might enhance their stress tolerance by using beneficial microorganisms for corals, or BMC.

To test this, the team selected six beneficial bacterial strains isolated from the coral Mussismilia hispida and used them to inoculate experimental cultures of M. hispida. At the same time, the corals were exposed to a heat stress treatment, with the temperature increasing to 30 degrees Celsius over the course of 10 days before dropping back down to 26 degrees Celsius. The researchers monitored the health of the corals and measured microbial diversity and metabolic parameters in treatments with and without probiotics or heat stress.

Initially, there was no difference — corals with and without probiotics reacted similarly at the peak temperature and both bleached. “At that point of the experiment, I thought, well, OK, we’re seeing similar responses between the treatments,” recalls Erika Santoro, the study’s lead author, who is now a postdoc at KAUST. “But then after we dropped the temperature, we observed a plot twist from the group that we treated with probiotic BMC. That was a really nice surprise.”

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