May 12, 2021
As I write this, I’m watching snow fall out my back window. Welcome to May in Yellowstone! Thank goodness for this moisture. The last couple of weeks I’ve been putting together a presentation for a virtual program focusing on Yellowstone. It’s fun as other naturalists have been part of this and we’ve had a chance to share our experiences and knowledge.
I’ll share with you some things I’ve learned preparing for a presentation called “Some like it Hot” that focuses on life in extreme environments (hotsprings) in Yellowstone. This is a significant region that NASA and astrobiologists have focused on to try and find what life may have looked like 3.5 billion years ago when early earth looked more like other places in the universe.
Although colors in hotsprings runoff is visible to the naked eye, an individual microbial cell is so small as to be completely invisible. It is only because of their vast numbers (colonies and pigments in those colonies) that we know they are there. I call these the “beautiful bacteria!”
So I ask you, “what is your favorite bacteria”? (fellow guide would ask his groups that question and heard some hilarious responses). “Microbial life is the oldest, largest reservoir of genetic diversity on our planet, dwarfing the biodiversity of all the plants and animals we can see with the naked eye that dwell in rain forests, coral reefs, and the world’s oceans.”
So now you are thinking, OK, this is a big story and I’m not sure I want to read this…yes, it’s a really big story! Yes, you need to read it because it tells the story of life. These microbes, which bacteria are part of the category of prokaryotes (single cell organisms without an enclosed nucleus), are what created the oxygen rich atmosphere we have on earth today. They evolved in some of the most extreme environments on early earth.
These are grouped with other “extremophiles” who can survive in a variety of other extreme environments. In some cases they survive super acidic, or even alkaline environments, such as those in Yellowstone. Other extremophiles can survive in a variety of environments that would be impossible for us. Many of the extremophiles live in other crazy places such as high salt environments, high in toxic metals or gases, cold, salty, or high pressure environments. They serve important ecological roles. Their history exhibits principles of ecology and ways in which geologic processes might have influenced biological evolution. The colors depend upon the ratio of chlorophyll to carotenoids. In the summer the chlorophyll content is often low, so that the microbial mats appear orange, red, or yellow due to carotenoids. In the winter, the mats are usually dark green, because at this time of year.
Bacteria are chatter boxes! They speak their own language within colonies (biofilms) and sometimes between other colonies. It’s called Quorum Sensing. When an announcement goes out bacteria use electrical & chemical signals to “talk” to each other. In this way microbes can powwow and synchronize the actions of a colony of billions of microscopically small individuals to function “like a microbial brain”. It’s not that surprising these organisms work together much more cooperatively than humans!
The communities formed by thermophiles living in the run-off from hot springs are like miniature forests. Microbes living on the surface of the bacterial mats perform photosynthesis to provide fuel for the community (like a forest canopy). This feeds the organisms living inside the mat. These microbes also decompose and recycle nutrients to the mat’s canopy helping the ecosystem thrive. An example is…Photosynthetic activity of cyanobacteria such as Lyptolyngbya form columns or pedestals. Oxygen bubbles rise in the mat, forcing the microbes upward. The higher formations capture more organic matter and sediment than the lower mats, which help build the columns. Called stromatolites or microbialites, these structures are similar to ancient microbial communities preserved in formations around the world.
Stromatolites found in ancient rocks are perhaps the most abundant and widespread evidence of early microbial ecosystems. Thermophile communities leave behind evidence of their shapes as biological “signatures.” Scientists compare the signatures of these recent stromatolites to the “old-timer” deposits. Some of these can be found in 350-million-year-old Australian sinter deposits or Glacier National Park. I would see these formations each time I led a group to Grinnell Glacier!
If stromatolites are a record of early life on our planet, they might be a record of life on other planets too. Imagine if life formed on Mars millions of years ago when Mars had shallow seas. We have always imagined life on other planets as “little green people” in spaceships!
So how does this relate to Yellowstone?
NASA has funded some of this research as they are using models of organisms like extremophiles to look for what could be living in other worlds. Scientists at Montana State University study the environment of Yellowstone to compare to early Earth because the conditions are similar. Early Earth was hot, wet, and had a lot of geothermal (or volcanic) activity. This description fits Yellowstone as well, making Yellowstone a good mirror of early Earth.
Heat stable enzymes from these organisms have been found to have multiple applications in biotechnology. Applications are used in the areas of genetics, medicine, forensics, environmental sciences, and alternative energy such as:
- Converting wood chips and other plant matter to biofuel
- Paint removers
- Toxic spills, radiation and mining clean-up
- Identification of tissue at a crime scene
- Fighting disease like cancer
- Identification of the Human Genome
- Creating vaccines like Covid-19
One of the most important discoveries in the last 50 years involves genetic duplication that was recognized in a Yellowstone organism called Thermus aquaticus. Pioneering microbiologist, Dr Thomas Brock, along with an undergraduate student, isolated a novel bacteria in the Lower Geyser basin of YNP. As it was living and thriving in temperatures around 70 C (158 F), a higher temperature than any other organism at that time, this was later named Thermus aquaticus. In order to survive at this temperature, Thermus aquaticus copies its own genetic information with a thermostable enzyme, DNA polymerase, in order to survive and replicate. (The enzyme is now called TAQ) The discovery of this DNA polymerase enzyme and its application in a process called Polymerase Chain Reaction (PCR) resulted in a Noble Prize for biochemist Kary Mullis in 1993 and has lead to the biotechnology revolution.
PCR has many research and practical applications. It is routinely used in DNA cloning, medical diagnostics, and forensic analysis of DNA. In 2001, guiding in Yellowstone, I pointed to a hot spring and talked about the discovery of the PCR enzyme and Dr Brock. A woman in the group gasped and shouted ” I use the TAQ enzyme in my lab everyday!” She was a biologist working with Breast Cancer researcher! She had no idea of the connection to Yellowstone; I loved this!
PCR acts as a sort of molecular copy machine, allowing for the duplication and amplification of DNA from a very small sample. PCR testing is now commonly used to detect genetic sequences in the world of forensics and medicine.
Jim I had an opportunity to do a one day seminar with Dr Brock in Yellowstone. He was delightful, super energetic and engaged with all of us. He left an impression on me that sparked my fascination with these invisible characters. He told us “not to sit on the ground” in an acidic feature we were visiting as it “could burn a hole in your pants!” with an impish grin!
Two organisms have been named for Dr Brock. One is Thermoanaerobacter brockii , first isolated in Yellowstone. T, brockii can survive in temperatures up to 80C (176 F) and it’s anerobic metabolism produced ethanol. Recently, a new group of climate-friendly microbes that seem to be helping the planet in the carbon cycle have been recognized. Living in hot springs, geothermal systems and hydrothermal sediments around the world, these microbes seem to be playing an important role in the global carbon cycle by helping break down decaying plants without producing the greenhouse gas methane. Some of these prokaryotes found recently have been classified into a phylum called Brockarchaeota for Tom Brock. He died April 4 of this year and leaves a legacy with his work.
Thanks for continuing to read about Greater Yellowstone! It’s been just over a year I’ve been writing this newsletter. It started with encouragement from a couple of good friends who are both inspirations to me. And it’s been fun doing this!
Best to all of you and Happy Trails this summer!