A new study from the Faculty of Medicine at the Hebrew University of Jerusalem sheds light on how bacterial motion influences the spread of antibiotic resistance. Led by Professor Sigal Ben-Yehuda and Professor Ilan Rosenshine from the Department of Microbiology and Molecular Genetics, the research uncovers a direct connection between the rotation of bacterial flagella—structures used for movement—and the activation of genes that enable bacteria to transfer DNA to one another.

This process, known as bacterial conjugation, is a key mechanism by which genetic traits, particularly antibiotic resistance, are shared among bacterial populations. While conjugation has traditionally been associated with bacteria attaching to solid surfaces, the team investigated pLS20, a widespread conjugative plasmid in Bacilli species, which behaves differently. The study shows that in liquid environments, where bacteria rely on movement to navigate, the rotation of flagella acts as a mechanical signal that turns on a set of genes required for DNA transfer.

The researchers discovered that this signal triggers gene expression in a specific subset of donor cells, which then form clusters with recipient bacteria. These multicellular clusters bring the two types of cells into close contact, facilitating the transfer of genetic material.