A freshwater bacterium can sense the direction of light by acting as a microscopic lens.

Spherical cyanobacteria called Synechocystis, which harvest energy from light, use protein appendages to pull themselves over wet surfaces towards light sources. A team led by Conrad Mullineaux at Queen Mary University of London found that the cells act as tiny lenses that bend and focus light. When the team illuminated one side of the cell, a bright spot appeared at the opposite end. Simulating this spot with a laser beam caused the Synechocystis cells to move away from the spot, towards the perceived source of light.

Light-sensing proteins embedded in the cellular membrane trigger the bacteria to move towards light, the researchers suggest.

eLife http://doi.org/bcgd (2016)