Over the years, I’ve been fortunate to work on a bunch of very esoteric projects.
I’ve found microbes that degrade honest-to-goodness solid waste (HGSW), recalcitrant chemicals (aromatic hydrocarbons, among others), harvest gold from the ground, etc.. The trick is finding the right microbes that effect the change desired. (In a few cases, the trick was forcing a mutation in the strain the deliver the desired results.)