Believe it or not, humans didn't invent the wheel. Long before we showed up, some of nature's tiniest organisms had already evolved wheel-like nanostructures to propel themselves through liquid media. Now, scientists have found a way to image bacteria's naturally occurring, biological wheels for the first time, New Scientist reports.

Most bacteria maneuver themselves around using tiny protein motors that power a spinning flagellum tail, which is no more than tens of nanometers wide. While scientists know that different motor structures produce different levels of mobility in bacteria, they haven't been able to study the details of these mechanisms—until now. According to the study recently published in the journal PNAS [PDF], researchers at Imperial College London used an electron microscope to capture the first-ever 3D renderings of these structures, which you can see below.

By freezing the bacteria through a process called electron cryo-tomography, they were able to image the motors from multiple angles. They looked at a handful of various bacteria samples—including Campylobacter and Salmonella—to see how their wheels differed. Flagella generate their torque from wheel-like structures around the motor called stators. Different bacteria have different amounts of stators, which in turn come in different shapes, sizes, and strength levels. Campylobacter, which has nearly double the stators of Salmonella, has enough propulsion power to penetrate your stomach lining.

The high-resolution images could be used by nanoroboticists to develop better motors in the future, or they could find a way to incorporate the biological wheels into their robots to avoid building them from scratch. Better understanding the mechanisms behind the structures could also help us to target harmful bacteria more efficiently. You can read the full report in PNAS.

Vibrio motor // Imperial College London

Salmonella motor // Imperial College London

Campylobacter motor // Imperial College London

[h/t New Scientist]