Colloquium Natural and Life Sciences - Annegret Wilde

How bacteria see the world

Sunlight, which drives photosynthesis, is the most important energy supplier for life on Earth. Photosynthetic cyanobacteria are the ancestors of chloroplasts and they are still very important primary producers in almost all habitats. Cyanobacteria can move on surfaces using so called pili towards or away from a light source to find optimal light conditions for photosynthesis. But how they can sense the direction of light? We found that the single bacterial cell acts as a very effective micro‐lens, focusing a sharp image of the light source close to the opposite (non‐illuminated) side of the cell. This bright light spot locally triggers a signal transduction chain, which then controls movement of the cell in response to the light source. I will show how we use physical and biological methods to measure the optical properties of very small cells.