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In recent years, scientists have turned up microbes living in the frigid waters of Antarctic lakes that are permanently covered with snow and a thick layer of ice. Scientists have found microbes thriving in the wind-blasted rocks and soil atop high mountain summits and in polar snow.
Now maybe all this doesn’t seem quite so amazing at first: after all, penguins waddle across the Antarctic ice floes and polar bears and walruses meander the Arctic tundra and even we humans can trek to the poles given enough layers of down, fleece and wool. But how in the world do microbes do it without the aid of blubber, fur or other obvious insulating protection? After all, cold kills or at least slows down lots of microbes—that’s why we put our food in refrigerators to keep it fresh longer.
Scientists studying microbes that thrive in the cold (which go by the fancy name of psychrophiles <sigh-crow-files>) have not yet discovered all the secrets to these microbes’ amazing cold-loving abilities. However, they have learned a couple of neat things.
Cold-loving microbes may not have fur or down-filled coats, but they do have special proteins or enzymes that help them shrug off the frigid chill. What are enzymes, you say? These are proteins that help make lots of chemical reactions take place inside cells and basically help cells do all the things they need to do to stay alive. So, psychrophilic <sigh-crow-fill-ick> enzymes are similar to the enzymes in microbes that live at normal temperatures, but the psychrophilic enzymes continue to function at temperatures below which normal enzymes get sluggish or stop working. How? It appears that enzymes in cold-adapted microbes have a little more flexibility in them because they’ve lost a few of the fastener molecules that keep these protein folded rigidly into a specific three-dimensional shape. (Proteins bunch up into 3-D shapes that are very important to how well they work.) Since these enzymes can flex a bit, they don’t need as much energy to do their thing, which is good in an environment where you can’t count on heat for energy.
Another way cold-loving microbes thrive in their chilly environments is keeping the membranes of their cells loose with molecules called fatty acids. Membranes are like plastic sacks with holes that surround the goopy fluid and all the parts inside of cells. A fatty acid is a long chain of carbon atoms strung together. Having a lot of these fatty acids keeps membranes fluid in low temperatures so they can continue to easily take in and release molecules—"food" and "wastes" basically—through their cells.
There’s a lot still to learn about how microbes live comfortably in super-cold temperatures. These are just a couple of the microbial tricks for beating the cold. Scientists are studying ways that we humans could put these psychrophilic enzymes to work for us, say in preserving foods without freezer burn, improving microbial clean up of pollution, and making new medicines.