New discovery about how bacteria navigate their environment could change the way we treat infections

Scientists at the University of Sheffield have discovered a new sensory ability in bacteria that could transform treatments for bacterial infections.

Until now, it was thought that bacteria were too small to directly sense differences in chemical concentrations. But contrary to what scientists had thought for decades, a new study has shown that bacteria can actually directly sense their chemical environment along the entire length of their cell body with an unprecedented degree of precision.

The research, published today in Microbiology of naturerepresents a key step towards the development of innovative treatments that manipulate bacterial motility to improve the effectiveness of antibiotics.

The study focused on Pseudomonas aeruginosa, which has been classified as a priority pathogen by the World Health Organization because of its ability to cause highly antibiotic-resistant infections in humans.

Lead author of the study, Dr William Durham, Senior Lecturer in Biological Physics in the Department of Physics and Astronomy at the University of Sheffield, said: “In principle, cells can determine whether they are moving towards or away from a nutrient source in two different ways.

“First, they can move randomly and measure whether the concentration is increasing or decreasing over time. The cells can also measure changes in concentration along the length of their body, allowing them to move directly toward the source. Our research demonstrates that bacteria can do the latter, something previously thought to be beyond their capabilities due to their small size.

“The bacteria then use this information to navigate across surfaces to chemical sources using tiny grappling hooks called pili.”

By combining innovative microfluidic experiments and new strains of P. aeruginosa whose motility systems were designed to be visualized directly using powerful microscopes, the researchers mapped how individual cells responded to precise changes in nutrient concentrations. They found that these cells can compare nutrient concentrations across the length of their cell body, a phenomenon called “spatial sensing.”

Dr Jamie Wheeler, a postdoctoral researcher in the Department of Physics and Astronomy at the University of Sheffield and lead author of the study, said: “This work revolutionises our understanding of how bacteria navigate and sense their environment. As such, it sheds new light on how bacteria might direct their motility during human infection and potentially how this could be manipulated by different clinical treatments.”

This discovery means that bacteria do not necessarily need to move to sense changes in their chemical environment, suggesting that densely packed bacteria in localized infections can use this information to guide their behavior. This ability raises new questions about the mechanisms bacteria use to make these microscopic measurements and how they might be manipulated by antimicrobial treatments.

Dr Wheeler added: “As is often the case, answering a question raises a whole series of unknowns. Exciting new experiments are already planned to continue writing this new chapter in our understanding of how bacteria navigate their environment.”