By Pesach Benson • 8 April, 2025

Jerusalem, 8 April, 2025 (TPS-IL) — Israeli researchers revealed that the way bacteria move plays a direct role in the spread of antibiotic resistance on Tuesday in a study that opens up new possibilities for fighting antibiotic resistance.

The research centered on bacterial conjugation, the process by which bacteria share genetic material, including antibiotic resistance. Hebrew University scientists led by Professors Sigal Ben-Yehuda and Ilan Rosenshine found that the rotation of the bacteria’s tail-like flagella acts as a mechanical signal triggering the conjugation process.

Till now, the prevailing understanding was that bacterial conjugation only took place on solid surfaces and that the tail’s rotation was only for movement.

But the findings, recently published in The EMBO Journal, a peer-reviewed journal, found that the tail’s movement, called flagellar rotation, takes place in liquid environments. The researchers also discovered that the tail’s rotational motion acts as a mechano-sensing mechanism causing donor cells to form multicellular clusters with recipient cells to facilitate efficient gene transfer. This helps the bacteria spread resistance genes, even in conditions previously thought to be less favorable for conjugation.

“This process of DNA transfer, called bacterial conjugation, has long been studied on solid surfaces,” said Prof. Ben-Yehuda. “What we found is that in liquid, it’s the rotation of the flagella that acts as a mechanical signal to kickstart this process.”

The study focused on pLS20, a widely distributed plasmid found in Bacilli subtilis, a common soil bacterium.

Researchers observed that rotating flagella triggered gene expression in donor cells, prompting them to form clusters with recipient bacteria. These clusters bring cells into close contact and facilitate DNA transfer. When flagellar rotation was blocked — either through genetic modification or by increasing the viscosity of the surrounding liquid — conjugation rates dropped sharply.

“It’s not just about having flagella,” Ben-Yehuda explained. “They need to rotate. That mechanical action is essential for signaling the bacteria to start sharing DNA.”

Since flagellar rotation is essential for triggering gene transfer, it presents a new potential target for antimicrobial strategies. Disrupting this mechanical signaling could help prevent the spread of resistance genes without killing bacteria outright.

The understanding that bacterial behavior in liquid environments such as the bloodstream, lungs or water systems is more dynamic than previously thought could also lead to better predictive models of how antibiotic resistance spreads.

“Our study brings about a novel notion that synchronizing DNA transfer with the bacterial motile lifestyle provides the plasmid with the advantage of spreading into remote ecological niches,” said Ben-Yehuda.