A frog’s life

Microbes can help preserve the health of wildlife. Recently, researchers discovered a bacterium that, in the wild, helps protect certain species of salamanders and frogs – and might, with the help of science, help save them from extinction.

All over the world, amphibian species have been laid low by the chytrid fungus, Batrachochytrium dendrobatididis, whose spores block respiration and nutrient absorption. This fast-spreading infection, called chytridiomycosis, may be the worst-ever infectious disease of vertebrate species as it rapidly devastates populations. Already, it has driven two species – the Costa Rican golden toad and the Australian gastric brooding frog – to extinction, and scientists fear that the disease may be responsible for around 100 other extinctions, with more to come.

The good news is that amphibians do have protective anti-fungal bacteria that naturally occur on their skin – even though this is not always enough to keep a virulent infection from overwhelming them. Researchers isolated one of these bacteria, Janthinobacterium lividum, from yellow-leg frogs of the Sierra Nevada mountains of California and brewed quantities of it in a laboratory. Then, they applied the solution to frogs in the lab, and exposed them to chytrid fungus. All of the treated frogs survived, and testing in the field got the same result: of a population of frogs in the wild, only those that were inoculated with the bacterial solution survived when the chytrid fungus swept through the habitat.

The fact that we can amplify the power of protective microbes is great news, and not just for amphibians. Researchers working with mosquitoes have successfully inoculated a species of mosquito with Wolbachia bacteria, making mosquitoes immune to the malaria parasite and therefore preventing transmission of the disease. A similar experiment was successful in preventing the transmission of dengue fever.

More research and testing is needed: a bacterium that works for one species doesn’t always work when transferred to another, suggesting that for each species and habitat, just the right bacteria may need to be isolated. But the initial successes point to a hopeful future in which we may be able to use microbial biodiversity as an invaluable resource for protecting other life forms – and that includes you!

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This post is also available in: French, Spanish