Light Control

These neat circles are colonies of Pseudomonas aeruginosa – a drug-resistant superbug that causes life-threatening infections in people with weakened immune systems, serious burns or health conditions like cystic fibrosis. What makes these bugs so bad is their ability to grow into thick, sticky layers known as biofilms, which provide protection from antibiotics and are difficult to shift. However, these images reveal a potential new weapon in the battle against bacterial biofilms: coloured light. Blue and red light have no effect on biofilm formation (top left and middle), but longer-wavelength far-red light creates a weak, fluffy colony that can’t form a biofilm (top right). The bottom row shows bacteria grown under the same colours but genetically altered so they don’t respond to light, proving that it’s the specific wavelength of light that hinders growth. Maybe shining far-red light on Pseudomonas infections could be a novel way of controlling these deadly superbugs.

Written by Kat Arney

Kat Arney

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Dr Kat Arney is an award-winning science writer, broadcaster and public speaker, and is the founder and Creative Director of First Create The Media.

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• Image adapted from work by Sampriti Mukherjee and colleagues
• Department of Molecular Biology, Princeton University, Princeton, NJ, USA
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in PLOS Biology, December 2019