Sugar Sugar

These little blobs are individual E. coli bacterial cells, which have been growing in sugary nutrient broth. They’re all genetically identical, so they should all be exactly the same. According to the panels on the left, showing the bacterial DNA (top) and outward appearance (bottom), there are no differences between them. But a closer look reveals that there’s something strange going on inside these little bugs. The bacteria are being grown in broth that contains two sugars – glucose and arabinose – which require different genes to be switched on in order to ‘eat’ them. The cells have been highlighted using coloured markers that reflect which sugar they’re feeding on, with cells using most glucose coloured red and those using most arabinose in green. It appears that even these seemingly indistinguishable bacteria have their own individual characteristics, providing insights into how differences in gene activity can arise from genetically identical cells.

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 from work by Nela Nikolic and colleagues
• Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
• Image originally published under a Creative Commons Licence (BY 4.0)
• Published in PLOS Genetics, December 2017