By Helena Villela
When you hear the word “bacteria,” you might think of germs, diseases or infections. But guess what? These tiny organisms often living in partnership with a lot of animals (including humans and corals!) are not always the bad guys. In fact, for corals, bacteria are like their secret super-mini-hero squad.
Just as humans rely on gut bacteria to digest food and absorb nutrients, corals have their own team of bacteria. These tiny helpers are vital to the corals, from providing nutrients to defending them against pathogens. Without them, corals would not survive. But, as we all know, not all bacteria are good. Some of them act like villains, waiting for a chance to cause trouble.
When everything is going well, the good bacteria keep the bad ones in check, maintaining a balanced ecosystem. But when corals get stressed— due to pollution, rising ocean temperatures, or other environmental threats—the bad bacteria can take over. If the good bacteria do not go back in control, the corals can get sick and even die.
Now, here is where it gets cool: scientists are using probiotics (the good bacteria that naturally live with healthy corals) to help them fight back! You have probably heard of probiotics in yogurt or supplements for humans, but did you know they are also used to help plants, fish, corals and even bees? These are called environmental probiotics. In 2017, a group of scientists came up with the idea of using probiotics for corals, calling them Beneficial Microorganisms for Corals (BMCs) (Peixoto et al. 2017). These BMCs act as coral’s health boosters, enhancing their defenses.
In 2019, the same team proved that BMCs could help corals survive heat stress and pathogens (Rosado et al. 2019). During the study, the coral nubbins treated with BMCs showed less bleaching and mortality compared to the untreated ones (control group). Turns out, adding the beneficial microbes helped the corals fight off the heat and pathogens, keeping them healthier under stress. Since then, more studies have shown that BMCs are a promising tool for protecting corals in tanks and in the wild. But there is a challenge: delivering these probiotics to corals is currently a lot of work. Scientists have to do it manually, which takes a great deal of time and effort (Figure 1). That is why researchers are getting creative, developing, and optimizing drones, underwater robots (ROVs), and automated devices to spread BMCs over larger areas.
Figure 1: Prof. Raquel Peixoto applying probiotics on corals. Photo: Morgan Bennett-Smith.
We know that coral reefs are the rainforests of the ocean. They are home to thousands of species, protect coastlines, and even help fight climate change by absorbing carbon dioxide. But they are in serious danger due to climate change, pollution, and other threats. While no single strategy will alone save corals, probiotics could be a powerful tool to buy them some time while we tackle the bigger problem: climate change.
So next time you think about bacteria, remember: that they are much more than just germs. They are some of the secret heroes helping to save our oceans. And keep in mind that there is no magic solution that will save the world’s coral reefs! Instead, it will require a collaborative effort among scientists, governments, and all of us working together.
References:
Rosado, P.M., Leite, D.C., Duarte, G.A., Chaloub, R.M., Jospin, G., Nunes da Rocha, U., Saraiva, J.P., Dini-Andreote, F., Eisen, J.A., Bourne, D.G. and Peixoto, R.S., 2019. Marine probiotics: increasing coral resistance to bleaching through microbiome manipulation. The ISME journal, 13(4), pp.921-936. https://doi.org/10.1038/s41396-018-0323-6
Peixoto, R.S., Rosado, P.M., Leite, D.C.D.A., Rosado, A.S. and Bourne, D.G., 2017. Beneficial microorganisms for corals (BMC): proposed mechanisms for coral health and resilience. Frontiers in microbiology, 8, p.341. doi: 10.3389/fmicb.2017.00341
Reefbites 