Thomas Brock, a microbiologist, was driving west to a laboratory
in Washington state in 1964 when he stopped off at Yellowstone National Park.
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“I’d never seen Yellowstone before,” he said in an interview in
2017. “I came in the south entrance, got out of my car, and there were all
these thermal areas spreading out from the hot springs into the lake. I was
stunned by the
microbes that were living in the hot springs, and nobody seemed
to know anything about them.”
What fascinated him, on what would be the first of many trips to
Yellowstone, were the blue-green algae living in a hot spring — proof that some
life could tolerate temperatures above the boiling point of water.
It was the beginning of research that led to a revolutionary
find in 1966: a species of bacteria that he called
Thermus aquaticus, which
thrived at 70 degrees Celsius (158 degrees Fahrenheit) or more.
The yellow bacteria — discovered by Brock and Hudson Freeze, his
undergraduate assistant at Indiana University — survived because all their
enzymes are stable at very high temperatures, including one,
Taq polymerase,
that replicates its own DNA and was essential to the invention of the process
behind the gold standard in COVID-19 testing.
Brock died April 4 at his home in Madison, Wisconsin. He was 94.
His wife, Katherine (Middleton) Brock, known as Kathie, said the
cause was complications of a fall.
Thermus aquaticus was used in the 1980s by biochemist
Kary B.Mullis to help create the polymerase chain reaction, or PCR, which earned him a
share of the 1993 Nobel Prize in chemistry.
“I remember running into Mullis at a meeting,” said Freeze, now
the director of the human genetics program at Sanford-Burnham Prebys Medical
Discovery Institute in San Diego. “And I said, ‘I’m the guy who found Thermus
aquaticus with Tom Brock,’ and he said that he used the very strain that we
isolated in Yellowstone.” (Brock had deposited cultures at the American Type
Culture Collection in Gaithersburg, Maryland.)
The PCR technology, which requires cycles of extreme heating and
cooling, can multiply small segments of DNA millions or even billions of times
in a short period. It has proved crucial in many ways, including the
identification of DNA at a crime scene and, more recently, detecting whether
someone has COVID-19.
“PCR is fundamental to everything we do in molecular biology
today,” said Yuka Manabe, a professor of medicine in the division of infectious
diseases at the Johns Hopkins University School of Medicine. “Mullis couldn’t
have done PCR without a rock-stable enzyme.”
Thomas Dale Brock was born Sept. 10, 1926, in Cleveland. His
father, Thomas, an engineer who ran the boiler room at a hospital, died when
Tom was 15, pushing him and his mother, Helen (Ringwald) Brock, a nurse, into
poverty. Tom, an only child, took jobs in stores to help her.
When he was a teenager, his interest in chemistry led him to set
up a small laboratory with a friend in the loft of a barn behind his house in
Chillicothe, Ohio, where he and his mother lived after his father’s death. They
experimented there with explosives and toxic gas.
After serving in the Navy’s electronics training program, Brock
earned three degrees at Ohio State University: a bachelor’s in botany and a
master’s and Ph.D. in mycology, the study of fungi.
With faculty jobs in short supply, Brock spent five years as a
research microbiologist at the Upjohn Co. before he was hired as an assistant
professor of biology at Western Reserve University (now Case Western Reserve
University) in Cleveland. After two years, he became a postdoctoral fellow in
the university’s medical school. In 1960, he joined the department of
bacteriology at Indiana University, Bloomington, where he taught medical
microbiology.
When he arrived at Yellowstone, he did not have grandiose
ambitions.
“I was just looking for a nice, simple ecosystem where I could
study microbial ecology,” he said in an interview for the website of the
University of Wisconsin, Madison, where he was a professor of natural sciences
in the department of bacteriology from 1971 to 1990. “At higher temperatures,
you don’t have the complications of having animals that eat all the microbes.”
Stephen Zinder worked with Brock as a student from 1974-77, a
period that included Brock’s last summer of work at Yellowstone and his
research into the ecology of Wisconsin’s lakes, including Lake Mendota in
Madison.
“He had an encyclopedic knowledge of microbiology and science in
general,” said Zinder, now a professor of microbiology at Cornell University.
“He was always learning and picking up new things.” He added, “I think his real
ability was to see things simply and to figure out simple techniques to find
out what the organisms were doing in their environment.”
Brock wrote or edited numerous books, including “Milestones in
Microbiology” (1961); “Biology of Microorganisms” (1970), now in its 16th
edition; and “A Eutrophic Lake: Lake Mendota, Wisconsin” (1985).
After retiring from the University of Wisconsin, Brock focused
on ecological strategies to restore oak savanna, prairie and marshland on 140
acres that he and his wife had purchased in Black Earth, Wisconsin, about 35
minutes from Madison.
The land, initially intended as a place for their two children
to play, later became the Pleasant Valley Conservancy.
To Brock, the discovery of Thermus aquaticus exemplified the
benefits of being given the freedom to perform fundamental research without
fixating on practical results.
“It’s kind of an interesting story,” he told Wyoming Public
Radio in 2020, “how research that was being done for just basic research,
trying to find out what kind of weird critters might be living in boiling water
in Yellowstone,” would eventually lead to “extremely widespread practical
applications.”
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