Scientists from the Queen Mary University of London have discovered how a freshwater bacteria called Synechocystis senses light and moves towards it, acting like an eyeball. The study was published in the February 9 issue of eLife.
The Synechocystis is 10,000 times smaller than an eyeball (0.003mm in diameter) and consists of just a single, spherical cell. The small bacteria uses the same physical principles as the eye of a camera or a human. When light hits the cell, it focuses on the opposite side of the sphere, allowing it to sense where it’s coming from and move in that direction.
Synechocystis is effectively a living lens, and its entire boundary is a retina. Technically, the cell sees the world the way humans do.
“The idea that bacteria can see their world in basically the same way that we do is pretty exciting,” the lead researcher of the study, Conrad Mullineaux, said in a press release.
Synechocystis is part of a large family of bacteria called cyanobacteria, which are ancient and abundant lifeforms that can make their own food through photosynthesis (this explains why they are attracted to bright light). In doing so, these microbes release oxygen filling the Earth’s atmosphere.
Scientists studied more deeply the photosynthetic process and revealed that bacterias are able to conduct light by their bodies acting as a lens. The light hit their spherical surface and retracted into a location on the other side of the cell, stimulating cell movement away from the focused spot. After light is detected, the bacteria sent tentacle-like structures called “pili” to the light source, which attached to the target surface and pulled the bacteria towards it.
“The fact that bacteria respond to light is one of the oldest scientific observations of their behaviour,” Mullineaux said. “Our observation that bacteria are optical objects is pretty obvious with hindsight, but we never thought of it until we saw it. And no one else noticed it before either, despite the fact that scientists have been looking at bacteria under microscopes for the last 340 years.”
Source: eLife Sciences