The thermometer in the hottest pool read 108°F. I inched down the astroturfed steps, gripping the wooden railing and grimacing at the way the heat stung my toes, a faint tinge of sulfur swirling up to my nostrils. At the bottom of the steps, I sat on a bench built into the timber beams lining the sides of the pool, the wood slippery under my skin. I made it barely five minutes before I retreated to the biggest pool at the hot springs, perhaps 10°F chillier than the little hot pot, the cooler water still warm enough to be a welcome respite from the autumn air as a few pellets of early snow dropped down from the clouds.
I couldn’t stay in the hottest pool for very long, but some organisms live their whole lives in water that hot – the wooden walls of each of the pools at the springs were coated with green mats of microbes, apparently thriving in the thermal pools.
Hot springs have long been known to harbor some interesting bacteria – in fact, the modern method for analyzing DNA was revolutionized in the mid-1980s by the isolation of Taq polymerase, an enzyme derived from the heat-loving bacteria Thermus aquaticus. Because Thermus aquaticus lives at 176°F, the enzymes it produces are able to function at high temperatures – making them extremely useful for industrial processes, including replicating and analyzing DNA (pdf). Thermus aquaticus was discovered in 1966 by Thomas Brock, a biology professor, in a hot spring pool in Yellowstone National Park. Brock’s discovery ushered in a new era of “bioprospecting” in the park – researchers and entrepreneurs began searching for microbes that produce heat-stable proteins and enzymes that might prove useful in high-temperature industrial processes (pdf).
Thermal springs continue to yield previously undiscovered microorganisms, as reported recently in the journal Geobiology. A team of researchers collected microbial samples from 28 springs located throughout the southwestern United States. They focused on springs that are mesothermal – in other words, “cool but above ambient temperature,” the sort of springs that humans like to slip into for a dip (many natural hot springs, including most of the Yellowstone hot springs, are too hot for swimming).
Genetic analysis of the samples revealed that the springs contained a wide variety of organisms, and that the mix of microbes – the community composition – in each spring was distinctive. The microbes that the researchers couldn’t match to known samples – the ones that may be novel – were primarily found in just four of the springs they sampled, suggesting that some springs have more potential for harboring new microbes than others.
I didn’t take any samples from the hot springs I visited, but the microbial community appeared to be doing quite well. Perhaps there was an unidentified microbe right under my fingertips when I ran my hands down the slick wooden walls of the pools, just waiting to be discovered.