Bacteria: The world’s oldest camera lens

10 Feb 2016

Researchers may have finally worked out how bacteria can ‘see’, with a multi-national team claiming bacteria and humans aren’t so different after all.

Named after their colour, cyanobacteria are 2.7bn years old, incredibly successful survivors, were the potential cause of mass extinctions and now, apparently, happen to look at things just like us.

Writing in eLife, a team of British and German researchers have claimed that bacterial cells act as the equivalent of a microscopic eyeball, an incredibly old, masterfully-evolved eyeball.

The way cyanobacteria – which can form in water bodies, or create that slippery green film on rocks – survive is through standard photosynthesis. And now it seems that we know far more about how they can see light, and even move towards it.

A walking octopus

Lead researcher Conrad Mullineaux just published his paper, which shows the bacteria cell body acts like a lens. As light hits the spherical surface, it refracts into a point on the other side of the cell. This triggers movement by the cell away from the focused spot.

They do this like how certain octopus can walk on land, with the bacteria growing tiny tentacle-like structures to drag it towards the light.

Bacteria sightBacteria are optical objects, each cell acting like a microscopic eyeball or the world’s oldest and smallest camera eye – via eLife

Pretty exciting

“The idea that bacteria can see their world in basically the same way that we do is pretty exciting,” said Mullineaux, a professor of microbiology at Queen Mary University of London.

“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,” he added.

Synechocystis, the species of cyanobacteria used in the study, serves as a spherical lens, but the team thinks that rod-shaped bacteria can also trap light and sense the direction it is coming from using refraction, acting like an optical fibre.

They also suggest that this finding is an example of convergent evolution between bacteria and animals, however, it’s far removed.

“The physical principles for the sensing of light by bacteria and the far more complex vision in animals are similar, but the biological structures are different,” said co-author Annegret Wilde from the University of Freiburg.

Oh, and that walking octopus reference, if you don’t believe me:

Main image via Shutterstock

Gordon Hunt was a journalist with Silicon Republic