Bacteria invented the wheel long before humans—and now scientists have a clear look of what these ancient machines look like, Popular Science reports. Many bacteria swim by spinning a flagellum, a propellerlike tail that pushes the microbes along. They spin this flagellum using a wheel-shaped molecular motor, the first images of which scientists published this week in the Proceedings of the National Academy of Sciences. Their special 3D-imaging technique—freezing three species of bacteria and then scanning them with an electron microscope—showed that each type of motor has a different strength, adapted to the species’ lifestyle. For example, Campylobacter jejuni has an extra-powerful motor, which it uses to swim through thick stomach mucous.
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