Scientists detected a faint whooshing noise from a single bacterium

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Experimental studies have shown that bacteria generate molecular noise. A research team from TU Delft managed to capture the faint noise of a single bacterium with graphene.

While observing the basic mechanics of graphene, the scientists wondered what would happen if graphene came into contact with a single biological object. To determine this, the scientists conducted experiments with E. coli bacteria in collaboration with Cees Dekker’s nanobiology group and Peter Steeneken’s nanomechanics group.

When the bacteria come into contact with drums made of ultra-thin bilayer graphene, they generate a random vibration with amplitudes of up to 60 nm. At the same time, it exerts forces of up to 6 nN on its surroundings.

What causes these small vibrations?

The answer lies in the biological processes of bacteria, with the main contribution being made by their flagella (tails on the cell surface that propel bacteria).

dr Farbod Alijani, who led the study, said: “What we saw was impressive! When a single bacterium adheres to the surface of a graphene drum, it produces random vibrations with amplitudes of just a few nanometers that we have been able to detect. We could hear the sound of a single bacterium!”

“To understand how tiny these flagellar blows on graphene are, one has to say that they are at least 10 billion times smaller than a boxer’s punch when he hits a punching bag. Still, these nanoscale beats can be turned into soundtracks and listened to – and how cool is that.”

Scientists found “This research has tremendous implications for antimicrobial resistance detection. The test results were clear: if the bacteria were resistant to the antibiotic, the oscillations continued at the same level. If the bacteria were susceptible to the drug, the vibrations diminished until an hour or two later, but then they were completely gone. Thanks to the high sensitivity of graphene drums, the phenomenon can be detected with just a single cell.”

animation shows how a graphene drum can reveal the sound of bacteria. The sound stops when a bacterium is killed by an antibiotic. CREDIT: Irek Roslon – TU Delft

Farbod Alijani: “For the future, we aim to optimize our single-cell graphene antibiotic sensitivity platform and validate it against a variety of pathogenic samples. Eventually, it can be used as an effective diagnostic toolkit for the rapid detection of antibiotic resistance in clinical practice.”

Peter Steeneken summarizes: “This would be an invaluable tool in the fight against antibiotic resistance, an ever-growing threat to human health around the world.”

Magazine reference:

  1. Rosłoń, IE, Japaridze, A., Steeneken, PG et al. Investigating the nanomotion of single bacteria using graphene drums. nat. Nanotechnology. (2022). DOI: 10.1038/s41565-022-01111-6
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