The article in reference is for materials used in bioleaching....

The article in reference is for materials used in bioleaching. I've found the most success for such materials to be in "heap leaching" where the materials (like phosphogypsum) is put into a pile with proper outlets at the bottom and the agent is poured on top and seeps its way through the pile taking the REEs (or whatever the organism is designed for) along for the ride out the bottom. Unfortunately, in situ leaching (like is currently done for most HRE) means just pouring the material on the top of a mountain and waiting for it to leach out the bottom somewhere (usually through lateral drill holes in the side of the mountain). It is then collected in a pond and recovered. In situ leaching is usually up to 40% effective, whereas, heap leaching can get up into the high 80's for efficiency.
I hope that helps. The article just says they found a special organism that likes REE.