MILWAUKEE, Wisconsin. – Like so many great scientific discoveries, Tom Brock began the research that would revolutionize the field of biology – and pave the way for the development of benchmark COVID-19 tests used to fight a pandemic – with a question.
In 1964, the microbiologist was hunting in the West when he stopped to visit Yellowstone National Park. It was the first time he had seen the scenic hot springs in the park.
“I got to the spa area and saw all these colors of what was obviously germs,” said Brock, then a professor at Indiana University. “No one seemed to know much about them.”
As the hot spring water flowed from the pools, it cooled, creating a range of temperatures and environments that were conducive to bacteria growth. But in the hottest parts of the springs, where temperatures ranged from 70 degrees Celsius to over 100 degrees Celsius – the boiling point of water – the springs were clear, considered uninhabitable.
Brock wanted to learn more about bacteria and see if any of them lived in the warmer waters.
The following summer, he returned to Yellowstone with a student research team and a grant from the National Science Foundation to research high temperature life. It was the start of what would become a decade of work studying the park’s microscopic creatures.
Brock was doing what is called basic research. He wasn’t sure where the work would take him or how his findings might be used in the future. The goal was as vague as it was grandiose: to advance scientific understanding of organisms living in one of Earth’s most extreme environments.
In doing so, he changed the world.
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In 1966, Brock and undergraduate student Hudson Freeze discovered a new bacterium that thrived in waters above 70 degrees Celsius. Brock named him Thermus aquaticus.
The discovery of this resistant bacteria revolutionized the fields of biology and medicine.
“A lot of people thought (the research) was kind of a specialized thing,” said Brock, now professor emeritus at the University of Wisconsin-Madison. “Working on organizations in Yellowstone in the summer was like a ‘vacation study’.”
What no one could have known at the time was that inside this bacteria was the key ingredient for the benchmark diagnostic tests that would be rolled out nationwide by the dozen. millions almost 50 years later, on the front lines in the fight against COVID-19.
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The key to the polymerase chain reaction, or PCR
As news of the discovery spread, biochemists across the country began to research Thermus Aquaticus“Inner workings,” Brock wrote in a 1997 article for the Genetics Society of America.
Brock and Freeze soon realized that the enzymes in bacteria – proteins that perform chemical reactions inside a cell – continued to function at temperatures even higher than the boiling point of water. Enzymes from other organisms cannot tolerate such heat; they lose their structure and stop functioning, like an egg that changes shape when placed in a hot pan.
One of Thermus aquaticus’ Enzymes are today the key ingredient in the polymerase chain reaction – PCR – that laboratories around the world are using to detect the virus that causes COVID-19.
PCR, a technique developed by biochemist Kary Mullis in the 1980s, is a basic procedure used to diagnose disease. PCR also plays a role in helping scientists detect DNA left behind at crime scenes, sequence genomes and track mutations like those in SARS-CoV-2, and determine a person’s ancestry. or the breed of a dog.

PCR can produce millions and billions of copies of DNA segments, amplifying even the smallest traces of genetic material from any germ, animal or person that scientists might be looking for. The process requires heating a sample to very high temperatures and then cooling it several times.
The enzyme Thermus aquaticus, called Taq polymerase, copies DNA to do more. Because it can withstand the heating process, labs are able to run tests much faster than they would without it, as other enzymes would be destroyed each time the sample was heated.
While there are other diagnostic tests available for COVID-19, scientists call PCR tests the gold standard because they are very precise, sensitive, and relatively fast. Even if there is only a small amount of virus in a patient’s sample, PCR will likely find it.

Before PCR became widely used in the 1990s, scientists would have to try growing viruses in the lab to diagnose diseases, a dangerous process that takes days or even weeks, said Al Bateman, director of Wisconsin State. Lab of Hygiene’s communicable disease. division.
Taq polymerase is so fundamental that one of the COVID-19 tests used by the state lab is named after it: TaqPath.
“All the benchmark PCR diagnostic tests: for COVID-19, for influenza, for (tuberculosis) – we run a lot of PCR here,” Bateman said. “None of this would exist.”
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The power of basic research
Brock was 10 when he got his first chemistry kit. His father set up a small laboratory for him in the basement of their house in Cleveland. He became interested in nature early on, exploring the old abandoned farmhouse near their home as a child.
At the age of 15, his father passed away, leaving Brock to take odd jobs for 25 cents an hour to support his family. He graduated from high school in the middle of World War II and immediately enlisted in the US Navy.
After the war, he enrolled at Ohio State University in 1946, where he studied as a recipient of the GI Bill. He eventually got his masters and doctorate degrees from Ohio State, and went to Indiana University as a professor in 1960. He moved to UW-Madison in 1971 and became president. of the bacteriology department in 1979.
The discovery of Thermus Aquaticus is far from where Brock’s search ended.
In a decade of researching hot springs and geysers in Yellowstone, Brock has authored over 100 articles based on his work.
During his career, he wrote some 250 articles and 20 books, and accumulated numerous awards.
Now 94, Brock is retired from UW-Madison but still lives about a mile from the university. He focused on conservation, running Pleasant Valley Conservancy in Wisconsin with his wife, Kathie.
Brock himself delayed his career, and in particular the discovery of Thermus Aquaticus, as a testament to the power of basic research.
“You know, you never know what’s going to happen,” Brock said of such scientific investigations.

He recalls that there had been public criticism of the NSF’s support for his work at the time, “It didn’t seem like a big deal, just a tourist attraction,” he said.
But Brock’s work in Yellowstone has led even more scientists to study “extremophiles,” microorganisms that live in extreme environments, a specialty that has unlocked theories about the origins of life on Earth and the possibility that life exists on other planets.
“I think Tom has had a catalytic effect on studies of extremophiles in general,” said Michael Cox, professor of biochemistry at UW-Madison. “He helped get the biology world interested in these unusual bacterial lifestyles and all kinds of things came out of it.”
The wide reach of this unique discovery is also an example of how science builds itself, sometimes in the most unexpected ways. It takes years of research, by countless curious scientists, to advance society’s knowledge base.
“I think it was the most amazing and rewarding thing I have seen in my entire scientific career,” said Freeze, now director of the human genetics program at the Sanford-Burnham-Prebys Medical Discovery Institute in La Jolla, California on the impact of the discovery.
“I know a number of people, friends of mine, who have said, ‘You always wanted to check the value of basic science? This is the best example, where you look at something that has no application and who has the right setting, with the right magic potions, you change the world, ”Freeze said.
Reflecting on the fruits of Brock’s curiosity, Bateman recalled a quote from another groundbreaking scientist: Louis Pasteur. “Chance favors only the prepared mind.”
It’s a sentiment Brock echoed when asked if he had any advice for scientists of the future.
“Study hard and keep an open mind,” he says.
Follow reporter Devi Shastri on Twitter at @DeviShastri.
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