Yellowstone and the COVID-19 test
A strange way of life that lives in the park’s hot springs makes a protein that changed the course of biomedical history. Orange and slimy microbial mats grow in the Great Prismatic Fountain of Yellowstone National Park.
Thomas Brock in Yellowstone
Microbiologist Thomas Brock was camping in Yellowstone National Park in the 1960s, when he found a species of bacteria that would transform medical science.
Brock investigated the tiny life forms that manage to get ahead in the boiling waters of the park’s thermal pools. He and a student found golden filamentous growth mats at Yellowstone’s Mushroom Spring that contained microbes that produced unusual heat-resistant enzymes.
Polymerase Chain Reaction (PCR)
Today, these enzymes are a key component of the polymerase chain reaction (PCR), a method used in laboratories around the world to study small samples of genetic material creating millions of copies.
This technique, which would have been impossible without the discovery of heat-resistant bacteria more than half a century ago, is now used to boost the virus signal in most available COVID-19 tests.
With the spread of the new coronavirus around the world, these tests have become the key to tracking – and perhaps slowing down – the advance of the pandemic. Although the tests have been slow to reach many countries, such as the United States, the PCR process that is the cornerstone of the test is relatively simple and fast, thanks to a cluster of bacteria that thrive in the Yellowstone hot springs. CPR technology helps save lives, “says Austin Shull, a molecular biologist at Presbyterian College in South Carolina.
Yellowstone’s Extreme Life
In the summer of 1964, Brock was driving across the country and stopped at Yellowstone. “Until then, I’ve never seen a hot spring before,” he recalls. He asked a park ranger how much he knew about the colorful microbe mats in the vaporous waters and was excited to discover that the organisms had barely been studied.
Brock knew that any life form in the hot springs would have to withstand extreme temperatures. Some pools were so hot that they were boiling, but she realized right away that life here could get ahead.
Cyanobacteria in Octopus Spring
A year later, Brock returned to Yellowstone to investigate the hot sources and saw a gelatinous mass on the brink of Octopus Spring, where the waters reached nearly 88 degrees Celsius, a temperature higher than scientists at the time believed could support life. Brock took a sample and remembers describing it in two words in his field diary: “Definitely alive.”
Eager to find out more, Brock and Hudson Freeze, a college student, returned in 1966 to investigate Mushroom Spring’s slimy cyanobacteria mats. Freeze cultivated some of the microbes to identify what lived in the system.
“Almost everyone got bacteria” says Brock. The discovery of one of the species, Thermus aquaticus, would end up revolutionizing molecular biology and would provide scientists with a new tool to manipulate and study DNA.
Using microbes to copy DNA and detect viruses: Since the discovery of the elegant double helix of DNA in 1953, scientists have faced the challenge of studying these tiny genetic molecules. To observe and understand different types of DNA, scientists needed large-scale samples.
In the 1980s, American biochemist Kary Mullis developed a technique to mimic the way a cell naturally copies its DNA to grow and divide. A set of primers or primers in English, short segments of DNA, mark the regions to be copied. Next, an enzyme called DNA polymerase assembles the building blocks of DNA in the desired sequence.
Yellowstone Bacteria Enzyme
DNA has to undergo several cycles of heating and cooling, and with each cycle the number of genetic copies is approximately doubled. However, in the first experiments, the high temperatures of each cycle damaged the DNA polymerase necessary to create those copies. “It’s almost like a photocopier,” says Shull of the technique.
“It’s like frying an egg, it would denature protein,” says Virginia Edgcomb, a microbial ecologist at the Woods Hole Institute of Oceanography in Massachusetts. The technique could be accomplished, but it was slow and heavy.
Mullis realized that an enzyme from the Yellowstone bacterium could survive heating and cooling cycles and speed up the process. Over the years, these enzymes have made it possible to automate the DNA copying process. Now researchers can produce up to hundreds of millions of genetic copies in a matter of hours.
For years, PCR testing was “very laborious, it took forever, but now it’s very simple and routine,” says Julie Huber, oceanographer at Woods Hole.
The COVID-19 test
The COVID-19 test uses this same process, but with a few more steps. The genetic material of the new coronavirus is RNA, not DNA, which is similar, but encodes its genetic instructions with different building blocks in a single strand. Virus RNA is first converted to DNA. The test also includes a fluorescent tag that highlights copies of the virus’ genetic material on a nasal swab. The more copies made with PCR, the brighter the sample.
When Brock went to Yellowstone to study the hot springs, he never imagined that his work would revolutionize the study of DNA. “I was free to do what we call basic research. Some said it was useless because it was not focused on practical purposes. What use would it be to search for live bacteria in hot springs and boiling pools in Yellowstone National Park? ”Brock said in an acceptance speech for an honorary degree from the University of Wisconsin-Madison.
But the finding has brought a gigantic change. Scientists now know that microbes have perfected unique techniques to thrive in nearly every extreme environment on the planet, from Yellowstone’s hot springs to deep-sea hydrothermal springs. These organisms contain a valuable collection of biological mechanisms that were previously unimaginable waiting for us to discover them.
Exploring Bacteria in Antarctica
“There is a whole range of diversity that would not be known or classified otherwise,” says Justin Lawrence, a doctoral candidate at the Georgia Institute of Technology studying microbial diversity in Antarctica. By cultivating a stronger understanding of the world of microbes, we can learn to protect ourselves from microscopic entities that could harm us, but to harness microbes for practical applications, researchers need to know what lives out there.
“Only when you get the agency do you get the code, can you play with it, and can you find out all this,” says Huber.
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