In a new study, KAUST scientists proposed a new effective countermeasure to prevent coral death. They suggested that the probiotic cocktail can help corals survive the heat and boost their resilience. Treating corals with a probiotic cocktail of beneficial bacteria increases survival after a coral reef bleaching event.
Climate change, which is a significant threat to oceans, affects coral reef ecosystems as well. Coral reefs have been undergoing unprecedented mass coral bleaching events in recent decades, fueled by ocean warming.
Ocean warming disrupts the symbiotic relationship between the coral host and its endosymbiotic algae, resulting in coral bleaching. In some cases, prolonged periods of heat stress and coral reef bleaching lead to coral death.
To test their approach, scientists conducted analysis on six beneficial bacterial strains coral Mussismilia hispida. They exposed the strains to bleaching conditions. Immunizing the strains with selected beneficial microorganisms for corals (BMC) or a saline solution placebo. All corals were affected by heat stress, but the observed “post-heat stress disorder” was mitigated by BMCs.
The introduction of beneficial microorganisms, aka probiotic cocktail, increases 60 percent to 100 percent survival rate. Also, it stabilizes their photosynthetic performance by the endosymbiotic algae.
Erika Santoro, the study’s lead author, who is now a postdoc at KAUST, said, “At that point of the experiment, I thought, well, OK, we see similar responses between the treatments. But then, after we dropped the temperature, we observed a plot twist from the group that we treated with probiotic BMC. That was a nice surprise.”
Scientists explain, “During the recovery period, BMC-treated corals had lower expression of genes involved in apoptosis and cellular reconstruction and increased expression of thermal stress protection genes. BMC treatment also altered the profile of the microbiome through incorporating some of the beneficial bacteria as well as other changes in the population structure.”
- Erika P. Santoro et al. Coral microbiome manipulation elicits metabolic and genetic restructuring to mitigate heat stress and evade mortality. DOI: 10.1126/sciadv.abg3088