While most people who know of Yellowstone are aware of its famous geysers and hot springs, many are surprised on their first visit to the park to see the varied and beautiful colors associated with these hot water phenomena. The earliest EuroAmerican explorers of the Yellowstone region noted the brilliant colors of its thermal features, but it was not until 1889 that geologist Walter H. Weed first recognized that the colorful hot springs deposits were microbial. Organisms that live in hot environments are called thermophiles, Latin for "temperature loving." Then, as now, it is astounding to think that there is life in waters too hot to touch.

Every thermal feature in Yellowstone is unique; each has its own temperature, flow rate, and water chemistry. These unique features determine what can live in the hot water. The upper temperature limit for vascular plants is around 113 degrees F (45 degrees C); for algae it is about 140 degrees F (60 degrees C). Consequently, these types of lifeforms are generally only found in the cooler channels that carry runoff away from thermal features. So what produces the colors within and along the edges of many of Yellowstone's steaming hot springs and pools? The colors are produced by single-celled bacteria called cyanobacteria, and the colors are from various cell pigments, including chlorophyll, the pigment essential for photosynthesis.

The upper temperature limit for the photosynthetic process is 161 degrees F (72 degrees C). Photosynthetic zones can be dramatic when seen in hot spring drainways. Runoff channels are frequently devoid of color in the center indicating that the temperature exceeds 161 degrees F. Edges of the channels are often cooler providing ideal habitat for cyanobacteria. Shades of green to pink to orange to yellow-brown to gray indicate the presence of various species of temperature-dependent bacteria.

The first life found growing above the photosynthetic temperature limit was discovered in Yellowstone's Lower Geyser Basin in 1967. Professor Thomas Brock, working under a Yellowstone National Park research permit, placed a clean microscope slide into the 176 degree F (80 degree C) waters of Mushroom Pool. After a few days, he viewed the slide under the microscope, and found it was covered with cells, which he grew in his laboratory and named Thermus aquaticus.

For hundreds of years, humans have known of and used bioprocesses to better their lives. For example, the processes used to make wine, bread, cheese, and beer all employ yeast, a single-celled fungus with biochemical properties (enzymes) that can ferment sugars. Enzymes are highly complex protein molecules that catalyze (speed up) biological reactions. However, enzymes rely on proper conditions to maintain their activity and are often destroyed by subtle changes in temperature or pH (level of acidity).

Yellowstone's geothermal ecosystem contains thousands of thermal features teaming with unusual lifeforms that withstand radical extremes of temperature and pH. Scientists realized that organisms living in 176 degree F (80 degree C) water contained enzymes that were stable at these high temperatures. Scientists began to search for other life growing above the photosynthetic limit; dozens of novel species were discovered. The first industrial use of heat-stable enzymes from Yellowstone thermophiles was in laundry detergent additives. However, with the knowledge that DNA is the informational code that directs the manufacture of a cell's enzymes and structures as well as advances in molecular biology and genetic engineering, a new use was discovered for Yellowstone's heat-stable enzymes.

In the late 1980s, DNA polymerase (the enzyme which catalyzes the replication of a cell's DNA) from Thermus aquaticus was employed in a laboratory process called the Polymerase Chain Reaction (PCR). This process allowed copying and amplification of "target" DNA in a test tube. The 1993 Nobel Prize for chemistry was awarded to the man who perfected this process, commonly called "DNA fingerprinting." The biotechnical and commercial applications that have resulted from this discovery are used today in analytical procedures that can convict criminals and diagnose diseases.

This phenomenal success that resulted from the discovery of a single Yellowstone thermophile has led to a huge increase in research activity in Yellowstone's geothermal habitats. More than 50 microbiology research projects are currently permitted in the park for the collection of samples. Recently, Diversa Inc., of San Diego, California, entered into an intellectual property agreement with the National Park Service. This contract granted Diversa, Inc. a license to commercially develop products from their research on Yellowstone's hot springs genetic resources. The park is paid a yearly fee for this privilege and, if any commercial applications result from a discovery here, will receive a share of the profits.

The earth's biological diversity has been declining for a number of years, making places such as national parks and conservation areas increasingly important as reservoirs of genetic diversity for scientific study and for the discovery of utilitarian products that may benefit mankind. As species are lost from this planet, they can never be replaced. When Yellowstone National Park was established 125 years ago, no one at the time could possibly have conceived that a microscopic bacterium, first found here, would change our world. What other secrets are preserved and protected here and in other national parks? Only time will tell.

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