They breathe rust, clean up polluted groundwater, generate electricity, and may harbor clues to the origins of life. That’s a lot for one family of microscopic bugs, but don’t be surprised when Derek Lovley wows the world with another wonder from the Geobacter genus of bacteria. “When we think we have hit the last of the big discoveries, something else comes along,” said Lovley, a microbiologist at the University of Massachusetts, Amherst.