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Discovered just over 60 years ago, extremophiles are bacteria, archaea, and eukarya that can survive in extremely salty, hot, cold, acidic, or radioactive environments.
A new review study explains that extremophiles have revolutionized medicine, and are invaluable allies in the fight against climate change.
Extremophiles are difficult to cultivate in the lab, but synthetic biology is making it possible to create organisms with extremophile-like attributes.
While visiting the famous hot springs at Yellowstone National Park in 1964, ecologist Tom Brock stumbled upon something very small that would overturn a major paradigm—a microorganism capable of surviving at temperatures much higher than scientists previously thought possible. That organism, subsequently named Thermus aquaticus by Brock and his research team, is widely regarded as one of the first extremophiles (organisms that thrive in hostile environments) ever discovered. T. aquaticus eventually went on to make a significant contribution to science by providing the crucial enzyme needed for the Polymerase Chain Reaction (PCR) technique that’s central to vaccine development. Now, a new review study published in the journal Frontiers in Microbiology showcases how Brock’s discovery was only the preamble to the amazing scientific findings these tiny microbes have made possible.
The bacterium discovered in Yellowstone is what’s known as a thermophile, meaning that it can withstand immensely hot temperatures. But other types of bacteria, archaea, and even a few eukarya, can also be adapted to extreme cold (psychrophiles), thrive in ultra-salty water (halophiles), withstand the punishing qualities of acid (acidophiles), or simply carry on living amid normally-life-threatening levels of radiation (radiophiles). Extremophiles exhibit super-robustness in the face of overwhelmingly inhospitable conditions, and scientists have discovered ways to leverage these abilities—as in the case of T. aquaticus—for immensely important purposes.
“Extremophiles exhibit remarkable adaptability in environments once considered uninhabitable,” the research team, made up of scientists from United Arab Emirates University, wrote. “They possess unique physiological and biochemical adaptations that enable them to survive and even thrive under such hostile conditions. These adaptations include robust DNA repair systems that counteract radiation damage, stress-resistant membrane structures and lipid compositions, accumulation of organic osmolytes, production of specialized enzymes, and protein-level modifications that maintain intracellular homeostasis.”
In the decades since their discovery, the science of extremophile biology has proven to be a goldmine of advances in practical applications for agriculture, textiles, biofuels, material science, and cosmetology, just to name a few. But the utility of these extreme organisms goes beyond mere practicality—they’ve also made heroic contributions to the realm of pure science. Extremophiles serve as a kind of living analog to LUCA, or Earth’s last universal common ancestor, which is the elusive organism from which all life on our planet descended.
Although we don’t know every detail about LUCA, scientists surmise that it was most likely an anaerobic prokaryotic extremophile living near a hydrothermal vent in the deep ocean. The reason is simple: If you were an oxygen-breathing mesophile (an organism that grows in moderate temperatures), Earth during the Hadean Eon wasn’t the place for you. But for extremophiles, it was just right.
“Extremophiles are found across all three domains of life including bacteria, archaea, and eukarya, sharing similar mechanisms that enable survival in extreme environments,” the authors wrote. “These shared traits likely arose through convergent evolution and/or the horizontal acquisition of stress-resistance genes from a common environmental gene pool.”
As the world faces problems caused by climate change, it’s likely that extremophiles will play a starring role in crafting solutions. Gene-editing tools like CRISPR/Cas9 are allowing scientists to bioengineer useful extremophiles capable of fixing carbon or consuming methane (a greenhouse gas that’s 28 times more potent than carbon dioxide). The big challenge moving forward is finding ways to create and culture these organisms, which arise by their very nature in highly specific conditions. Scientists hope that the arrival of synthetic biology will allow them to create organisms with the extremophile properties needed for practical applications, conveniently nestled in the bodies of more easily cultivated organisms.
To solve some of the world’s very big problems, scientists may have to turn to the world of the very small.
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