Seventy-five miles west of the State House, between Worcester and Springfield, a huge reservoir built in the 1930s holds the water that ultimately gushes from Boston's showerheads every morning. On the western shore of this 39-square-mile lake, the Quabbin, near the town of Pelham, there stands a forest of hemlocks and beeches. Running through the forest is a small tributary that feeds into a stream that empties into the Quabbin. And at the bottom of that tributary is a muck of partially decayed leaves and sticks. In 1996, UMass Amherst microbiologist Thomas Warnick waded into the muck, leaned down, and dug up a tablespoonful. He scooped the black slop into a jar and sealed the lid tightly. He was holding what just might be the Holy Grail of microbiology.

At the time, of course, Warnick didn't know that. He simply climbed out of the water and an hour later was back in the Amherst lab of his colleague, professor Susan Leschine, where he stuck the jar in a pile of containers holding the finest soil from Brazil, Mexico, France, and Hawaii. Leschine was researching microbes that break down plant waste-and within the Quabbin sample, she soon isolated an unusual bug. When she looked through her microscope, she saw a single-celled microbe that wasn't round and fat like the ones collected from around the globe, but slender, with a circular spore at one end, which made it resemble a tiny lollipop. She came to call this microbe "Q," a nod to its reservoir home.

Over time Leschine discovered that Q not only looked different from any microbe she had seen, but also acted like no other microbe. It had the ability to home in on many compounds-particularly cellulose (the fibrous, insoluble molecules that form a plant's cell walls), and turn it into sugars, and then, even more surprising, transform the sugars into pure ethanol. This was huge: Currently, plant waste has to be run through machines (which consume energy of their own) in order to make ethanol, a process that carries a steep price tag. But Q could make ethanol on its own-in one step, with no machinery involved. Its ethanol would be nearly as clean a power source as solar or wind. All of which meant Q could probably make someone a lot of money, too.