Cambridge, Mass. - January 23, 2012 - New research at Harvard explains how bacterial biofilms expand to form slimy mats on teeth, pipes, surgical instruments, and crops.
Through experiment and mathematical analysis, researchers have shown that the extracellular matrix (ECM), a mesh of proteins and sugars that can form outside bacterial cells, creates osmotic pressure that forces biofilms to swell and spread.
The ECM mechanism is so powerful that it can increase the radius of some biofilms five-fold within 24 hours.
The results have been published in the Proceedings of the National Academy of Sciences.
Biofilms, large colonies of bacteria that adhere to surfaces, can be harmful in a wide range of settings, resulting in tooth decay, hospital infections, agricultural damage, and corrosion. Finding ways to control or eliminate biofilms is a priority for many industries.
In order for a biofilm to grow, a group of bacterial cells must first adhere to a surface and then proliferate and spread. When a vast number of cells are present, this can translate into the creation of a filmy surface spanning several meters.
"Our work challenges the common picture of biofilms as sedentary communities by showing how cells in a biofilm cooperate to colonize surfaces," says lead author Agnese Seminara, a research associate at the Harvard School of Engineering and Applied Sciences (SEAS).
Several types of biofilms have been characterized based on composition and antibiotic resistance, but until now it has not been clear what roles the whip-like flagella and the ECM play in the outward movement of cells.
While the presence of a flagellum has traditionally been associated with greater movement capability, the new research has found that a flagellum actually confers little advantage in the formation of biofilms. In the Harvard study, mutant bacteria lacking flagella were able to spread at almost the same
|Contact: Caroline Perry|