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.
An underwater view of microbes blanketing a wooden beam supporting the side of the larger, cooler thermal pool.
(Image by Emily Benson)
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.
A swimmer's view of the changing rooms at the hot springs.
(Image by Emily Benson)