Call it high-altitude kombucha: CU Boulder biologist Valerie McKenzie has developed a probiotic solution that inoculates boreal toads from a virulent infection. Once common throughout the Mountain West, the mountain-dwelling toads have become increasingly threatened over the past three decades by a fungus that invades the amphibians’ skin cells and releases spores that interfere with vital bodily functions. The Colorado boreal toad population is considered endangered. In conjunction with Colorado Parks and Wildlife, McKenzie and her team developed an anti-fungal solution that incorporates naturally occurring beneficial bacteria from the toads’ own habitat. (The liquid’s distinctive purple color led McKenzie’s students to dub the project “Operation Purple Rain.”) The survival rate for toads that soaked in the solution for 12 hours increased by 40 percent, providing an encouraging proof of concept for fish and game managers s they search for a natural way to revitalize a threatened species.