Grappling hooks help bacteria slingshot forward

Like tiny mountaineers, bacteria use grappling hooks to pull themselves across a surface – and can get an extra boost by releasing one of the taut lines to slingshot themselves forward. Thwarting them could help combat the biofilms behind hospital infections.

Fan Jin and Gerard Wong of the University of California, Los Angeles, filmed the bacterium Pseudomonas aeruginosa crawling through a viscous medium on a glass surface. They then analysed how it moved using an algorithm. This confirmed what biologists had long suspected: many bacteria use hair-like appendages called pili as grappling hooks to pull themselves along a surface.

But the algorithms also picked up on something else: sometimes a bacterium's rear end performed a jittery but purposeful little dance. Instead of merely contracting their pili, the bacteria released one taut pilus from the surface altogether, sending their behinds skittering across the surface. This fired the cell forwards 20 times faster than contracting pili.

"The paper is interesting and suggests aspects of pilus-based cell movement that I had not considered," says Mark McBride of the University of Wisconsin-Milwaukee, who also studies bacterial movement but was not involved in the study.

Read more at New Scientist