In July of 2000, during the long, unbroken night of the Antarctic winter, graduate student Jack Gilbert found himself careening through the darkness on a quad-bike. Driving over rocky hills along the continent’s eastern shore, he finally arrived at Ace Lake—a salty body of water that freezes over for several months of the year.
It is a truly inhospitable environment, but it still harbors life—microbes, thriving in its frigid waters. These extreme survivors were the organisms Gilbert was there to study. He reached them by drilling through 1.4 meters of ice and pulling up samples of water. Then, he retired to a bare-bones hut for the night.
Gilbert had to wrap up warm to avoid freezing to death. But microbes can survive in the planet’s coldest places through other means. Some produce antifreeze proteins—molecules that latch onto small ice crystals and stop them from growing bigger. By releasing these proteins into the space around them, the microbes can lower the freezing point of water and create a network of liquid in which they swim and feed.
Among the hundreds of cold-loving microbes that Gilbert scooped up from Ace Lake, he found that one produced an “uncharacteristically powerful” antifreeze. It was called Marinomonas primoryensis. It had only been discovered the year before, and it was clearly doing something unexpected. For a start, its antifreeze was a titan of a molecule—between 30 and 50 times bigger than the average protein, and almost half as long as the microbe that makes it.