Hold On! Studying Sticky Bacteria
Humans respond to situations via our nervous systems — complex collections of nerve cells that send signals around our bodies and brains. Bacteria manage to move, find food, and react to their surroundings by different methods than our own, some of which have remained a mystery until now.
As part of a multi-university collaboration, Professor Nicolas Biais (Brooklyn College, The Graduate Center) and Ph.D. student Jingbo Kan investigated how bacteria sense surfaces. Their findings are published in Science.
“Scientists have studied bacteria mostly as single, free-swimming cells in liquid,” Biais says, “but it turns out that most bacteria ‘in the wild’ live in close-knit aggregates, called biofilms, on top of surfaces.” Figuring out what causes bacteria to grab hold of surfaces and create the beginnings of a biofilm could help scientists control bacterial growth.
Many bacteria are covered in short, sticky appendages called pili. Due to pili’s small size, it’s been harder to study them, but Biais and his team developed a new technique to watch the hair-like structures up close on the model species Caulobacter crescentus. When bacteria “swim” through liquid, they extend and retract their pili. If a C. crescentus bacterium comes close enough to a surface for its pili to touch and stick, it becomes difficult for the pili to retract. When the bacterium experiences such resistance, it releases an adhesive called holdfast, helping strengthen its attachment to the surface.
Understanding how bacteria “feel” and latch onto surfaces may help researchers learn to control the growth of these biofilms — for both good and bad bacteria. The next step, Biais says, is to uncover the link between pili resistance and adhesive production — how the former signals the latter to start.
“We are interested in how exactly they sense the force they generate,” he explains. “It could be that sensing mechanical forces in between bacteria, or between bacteria and solid surfaces, is enough to change the genetic program they follow.”
Explore This Work
“Obstruction of pilus retraction stimulates bacterial surface sensing”
“Biology Professor Nicolas Biais and Colleagues Identify Mechanism Bacteria Use to Attach to Surfaces” (Brooklyn College)