The Next Big Thing #1: Wildlife Probiotics
Posted by Richard Conniff on December 27, 2013
A few years ago, herpetologist Reid Harris of James Madison University was puzzling over the strange way in which some female salamanders weave in and out among the eggs in their nests. It turned out that the mama was inoculating the eggs with antifungal bacteria from her skin—and that this probiotic treatment protected them from a common egg fungus.
It made Reid and a colleague, Vance Vredenburg of San Francisco State University, contemplate using microbes to fight chytrid fungus, an epidemic killer of amphibians worldwide. When this deadly blight strikes, fungal spores enter the animal’s skin, block normal respiration, and cause listlessness and lingering death. Over the past few decades, the fungus has contributed to the extinction of an estimated 100 amphibian species, with many more to come—possibly including California’s endangered mountain yellow-legged frogs.
Following Reid’s example, Vredenburg found that yellow-legged frogs also carry an antifungal bacteria species on their skin—but not always enough of it to defeat the chytrid fungus. He began to brew up the bacteria in his lab, producing buckets of purple liquid. Then he briefly dipped lab-reared yellow-legged frogs into this probiotic bath and, a few days later, exposed them to the chytrid fungus. In the group that received the probiotic treatment, all of the frogs survived. In the untreated control group, 80 percent died.
The right microbes could also be the key to keeping some species alive and breeding in captivity. For instance, tamarins and marmosets in zoos are prone to callitrichid wasting syndrome, characterized by diarrhea, loss of hair, and paralysis of the hind limbs—ending in death. Researchers have generally suspected that the choice of food is the problem. But maybe what these monkeys really lack are the microbes necessary to digest it, the authors of a recent editorial in the journal Conservation Biology suggest. The idea of managing the microbiomes of animals still seems strange and unlikely to zoos. But that’s how physicians felt about the human microbiome a few years ago. New discoveries about how microbes shape animal health will take hold in the care of captive animals, much as they have in the treatment of human illness.
Microbiome research is simultaneously frustrating and tantalizing: microbial communities are astonishingly diverse and can vary dramatically from place to place—or species to species. This means that getting microbial conservation methods to work will require patience and a high degree of precision. The tantalizing part is that sequencing technology is now cheap enough to make that kind of precision practical.