Nature News from GYE #16 November 7, 2020

Yellowstone National Park is now closed to private vehicles with the exception of the road that goes from the North gate to the NW gate.  Winter season for these roads is December 15-March 15 and is open only to over the snow traffic.  The day before the closure I joined two friends for a walk through the Upper Geyser Basin boardwalks and beyond.  What a beautiful day we had as we watched Grand Geyser erupt

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Grand Geyser

and observed changes in some of the thermal pools as the temperature cycles throughout time.  Temperatures in the pools range from the very hottest measuring just above boiling point in the deepest part of the pool, all the way down to  temperatures that would be tolerable for us humans .  Along with extreme temps, the water could be very acidic (pH 0-5 such as pools in Norris geyser basin or Mud volcano) or neutral to alkaline (pH 7-11 as is the case with many of the springs in the upper and lower geyser basin such as Crested Pool and Ear Spring ). 

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This is one reason why swimming in thermal features in Yellowstone is not permitted. All of these conditions create the perfect habitat for microbes (single cell organisms) which thrive in extreme conditions. Thousands of varieties of extremophiles are found in Yellowstone’s thermal basins. Many of the springs in Yellowstone contain heat loving organisms (thermophiles).  These are not visible unless they live together in communities of millions or billions of cells, which are found in microbial mats. 

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The colorful bands we see in the pools are not typically mineral in origin, but biological.   The mats are like neighborhoods of different types of microbes.  In the top layers of the mats the organisms receive more sunlight and photosynthetic cells create bright pigments.   Bottom layers consist of microbes that are capable of surviving in dark conditions. The photosynthetic microbes are called cyanobacteria.  Dr WA Setchel first discovered these thermophiles in 1898 and referred to them as Blue Green algae. Different microbes can survive in different temperatures. Each cyanobacteria has different pigments which we can recognize by the color. Becsuse they all survive at different temperatures, we can use the colors to guess a temperature gradient!

Temperature gradients according to color photo from Thermal Biology Institute

For decades these organisms fascinated biologists with their ability to live in temperatures like this, some above the upper limits for photosynthesis. Most of us look at those pools and think, “wow, that is beautiful!”

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Grand Prismatic Spring
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Canary Spring

Dr Tom Brock, a retired microbiologist who currently holds the E.B. Fred Professor of Natural Sciences Emeritus at the University of Wisconsin-Madison, first collected and identified various types of these organisms.  We took a one day workshop from Tom many years ago with the Yellowstone Institute field studies.  He is delightful, brilliant, energetic and inspired an interest in these beyond what I’d learned in college.  Our day with him was too short!   Tom isolated and identified Thermus aquaticus in the 1960s. These bacteria that live in very specific temperature range of 149 degrees to 158 degrees but can survive in temperatures 122 to 176.  Thermus aquaticus and a polymerase enzyme found in this organism (taq polymerase) revolutionized DNA analysis.  The ability to quickly “fingerprint” DNA  is the basis of how most Covid 19 testing is done today.  I’ll attempt a quick description of how this functions. 

Proteins in most cells denature at higher temperatures, but not in thermopiles.  15 years after these organisms were identified by Dr Brock, a process to duplicate segments of a DNA strand more quickly and inexpensively was designed using an enzyme from T. aquaticus.  The process is called Polymerase Chain Reaction.  Segments of a DNA (or RNA in the case of a virus) strand can be amplified to get large enough samples to identify the tissue.  This technique is used in medical research, forensic research, and even researching your family history research (think “23 and me”).  The human genome was identified using this enzyme which is called TAQ (thermus aquaticus) polymerase.  On a trip I was guiding many years ago, after describing the presence of thermophiles and talking about TAQ one of my guests excitedly told me “I use TAQ in my lab every day!”  She was a medical researcher and was delighted to see the connection between Yellowstone hot springs and her work.

In this time of Covid, we have come to depend on testing which uses these polymerase enzymes on tissue/secretions in the nostrils collected (from the nasal swab) to detect the presence of Covid genetic material. 

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Bear facemask

Without the discovery of Thermus aquaticus and ultimately the polymerase enzyme, these tests would not be possible. 

As I mentioned earlier, enzymes from other extremophiles have been explored for other uses and applications.  This biotechnology (the application of an organism or part of an organism to make a product or process) includes mitigation of toxins in mine tailings and oil spills, brewing beer, creating new crops and even the rise of antibiotics!  So much information is available about this topic and I find it very exciting, but will spare you any more on this.  But remember, if anyone ever asks you” what is your favorite bacteria?” you can answer very confidently, “Thermus aquaticus” and let them know it lives in places like Yellowstone!

I encourage you to take a look at this 8 minute YouTube film featuring the Ameba Sisters.

 It’s a delightful and imaginative way to learn about PCR (polymerase chain reaction) and how some of this works.  And remember, when you look at the beauty of Yellowstone’s hot springs, boundaries of art and science are crossed to bring us into a world we never imagined.

From my home to yours, I wish you healthy days ahead.


If you have questions or want to contact me send a note to

Wolf and bison tracks in a bacterial mat!

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