How Yellowstone Revolutionized Biotechnology

How Yellowstone Revolutionized Biotechnology
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Life is capable of thriving in the most inhospitable places. The photograph above, which I took on my recent trip to Yellowstone National Park, shows Morning Glory Pool, a hot spring that is a short hike from Old Faithful. It's named after the purplish-blue morning glory flower, but the pool no longer has that color, which was due to a particular type of thermophilic (heat-loving) microbe. That is because ignoramuses threw coins and other debris into the pool, blocking the vents and lowering its temperature, which allowed microbes of other colors to grow. According to YellowstonePark.com:

"In 1950 the water level was lowered by siphoning which induced the pool to erupt. Socks, bath towels, 76 handkerchiefs, $86.27 in pennies, $8.10 in other coins came up; in all, 112 different objects were removed from Morning Glory."

(Honestly, I think the trashed up version of Morning Glory with its rainbow of colors is prettier than the original, pristine version. But, you can judge for yourself here.)

Surreal beauty isn't the only thing that Yellowstone's microbes have given us. Arguably, the most important enzyme ever discovered was found in a bacterium that lived in one of Yellowstone's hot springs. That microbe, along with its amazing enzyme, revolutionized molecular biology and helped birth modern biotechnology.

In 1969, a microbiologist by the name of Thomas D. Brock was poking around Yellowstone. He took samples of hot spring water back to his laboratory and cultured the bacteria found within them in conditions that mimicked the hot spring. He isolated a bacterium, which he called Thermus aquaticus (PDF), that optimally grew at a toasty 70 deg C (158 deg F). Little did he know that this basic scientific discovery would come in handy about two decades later.

In 1983, the LSD-using, AIDS-denying, UFO-believing, yet somehow Nobel Prize-winning biochemist Kary Mullis invented a technique to multiply small segments of DNA. The process, called polymerase chain reaction (PCR), is now a common procedure used in research and medical laboratories across the world. In fact, molecular biology wouldn't even be possible without this reaction. Because DNA manipulation is not terribly efficient, many copies of identical molecules are required to do even basic things, such as cloning. PCR solves this by amplifying DNA segments exponentially; i.e., after just a few hours, a single segment of DNA can be converted into several billion identical copies.

For the reaction to occur properly, PCR requires both high temperatures and a DNA replicating enzyme called polymerase. Originally, the polymerase came from the gut bug E. coli. However, E. coli preferentially grows at human body temperature, and its enzymes begin malfunctioning at temperatures above 37 deg C (98.6 deg F). However, this is far below the temperature required for PCR to work, which requires a range of around 68 to 95 deg C (154 to 203 deg F). As a result, the E. coli polymerase continuously broke down, and scientists had to keep adding more polymerase in order to keep the reaction going.

This was slow, tedious, and inefficient. If only there was a DNA replicating enzyme capable of withstanding high temperature...

Aha! Re-enter Yellowstone. Dr. Brock's bacterium, Thermus aquaticus ("Taq"), thrives at searing temperatures. It stands to reason, therefore, that its polymerase works optimally at high temperatures. And, indeed, it does. Taq polymerase does not break down at high temperature, and hence, the reaction can proceed quickly and smoothly without human intervention. In 1988, Dr. Mullis and a team of researchers published this breakthrough in the journal Science.

PCR's fundamental problem had been solved, and Taq polymerase permanently replaced E. coli polymerase as the DNA replication enzyme in PCR. It is not an exaggeration to say that Taq polymerase is now sitting in thousands of laboratories all over the world.

So, next time you visit Yellowstone, keep in mind that the beautiful hot springs around you played a direct role in the biotechnology revolution!

Other sources: Brock Biology of Microorganisms, History of Polymerase Chain Reaction (Wikipedia)

(Photo: Alex Berezow)

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