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Going to Extremes

ON THE ICY BOARDWALK ABOVE BLACK POOL, Tom Schoenfeld is working as fast as his numbing fingers will allow. He lowers a hose into the steaming pool, one of dozens of hot springs in the West Thumb portion of Yellowstone National Park, and then slides the other end into a keg-sized plastic jug. Shuffling along the slick wood planks, he begins piecing together the rest of the water filtration system that he developed for Lucigen Corporation, a Madison-area biotech company where he is vice president of enzyme discovery. The system, which concentrates the bacteria and viruses living within the spring, takes about 30 minutes to set up and an additional two hours to produce a couple of liters of teeming liquid. And though Schoenfeld arrived here at the break of dawn on this freezing September morning, he barely has enough time to get his work done before the tourists arrive. Tourists always delay things.

Researchers who study extremeophiles are partly motivated by curiosity, but also by the realization that extreme forms of life, like high-endurance athletes, have extraordinary abilities.

Despite its name, Black Pool is gemstone blue and perfectly clear. Its scalding waters produce a thick steam that rises from the pool and floats across the boardwalk, enveloping Schoenfeld in a fine mist. Water droplets soak his clothes and frost his eyelashes. As he reaches to switch on the generator that powers his equipment, he hesitates. There’s water all over it-and on the electrical cords leading to the pumps.

“Wear your gloves when you turn that on, man,” says David Mead, Lucigen’s president, who has accompanied Schoenfeld on seven visits to Yellowstone’s hot springs. As much as they can, the two look out for each other in the field and so far so good. Neither has been electrocuted, and they hope to keep it that way.

Electric shock, however, is only one of many perils they face collecting biological samples from Yellowstone’s springs. Once, a herd of unruly bison flushed the researchers from the edge of a backcountry pool, forcing them to wait several hours before they could return to collect Schoenfeld’s equipment. Another time, hiking through a dense forest, Mead tripped and narrowly missed impaling himself on the jagged branch of a downed tree. But above all else, they worry about the hot springs themselves. According to the book Death in Yellowstone, at least 19 people have died after falling or jumping unwittingly into the park’s pools, which are heated by an underground volcano. And as the book relates in sometimes gruesome detail, no matter how quickly a person scrambles out, falling into near-boiling water is a death sentence.

But for Schoenfeld and Mead, these risks are worth taking. That’s because they believe there are million-dollar microbes living in the park’s pools-bugs that, if found and studied, could unlock the doors to major medical breakthroughs and biotechnological advances. And if history is any guide, the bugs are almost certainly there, surviving and thriving in conditions that would kill almost any other form of life.

All Schoenfeld and Mead have to do is find one of them.

Welcome to the adventurous world of extreme microbiology. Like hundreds of other research scientists, Mead and Schoenfeld travel to Yellowstone to seek out extremeophiles-microorganisms that thrive in extremes of temperature and pressure and other inhospitable environments. These bacteria and viruses survive not only in hot springs but in metal-contaminated soils, pools of acid and lakes so salty that crystals bejewel the shoreline. The researchers who seek them out are partly motivated by curiosity, but also by the realization that extreme forms of life, like high-endurance athletes, have some extraordinary abilities. They harbor powerful proteins-known as enzymes-that enable them to make the most of their surroundings, efficiently turning otherwise inaccessible materials into the food and energy needed to sustain life.

“The bottom line,” explains UW-Madison microbial geologist Eric Roden, who teaches an undergraduate course on extremophiles, “is that extremophiles can do things that other organisms can not.”

Scientists first stumbled onto these rare organisms just a half century ago, when microbial ecologist Thomas Brock, then a professor at Indiana University, found a type of bacteria living in Yellowstone’s Mushroom Spring. Brock, now an emeritus professor of bacteriology at UW-Madison, had been searching for an ecosystem hot enough to support only a few forms of life. On a field trip to Yellowstone in 1964, he began examining the spring’s outflow channel. Starting at the cool end of the channel, where a lush, colorful mat of organisms covered the streambed, he worked his way up to hotter and hotter sections.

“When I got up close (to the spring), I started seeing this stuff,” says Brock, who joined the UW-Madison faculty in 1970. “It didn’t have any pigments. It didn’t have any chlorophyll or anything like that, but it looked like it was alive.”

And it was. Brock was able to grow and study this “stuff” in the lab, and in this way discovered the first extremophile, a heat-loving bacterium he named Thermus aquaticus, which is capable of growing at temperatures up to 80 degrees Celsius, not far below the boiling point of water. (Later, it was discovered that T. aquaticus lives in most residential hot water heaters, a harmless squatter.)

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