Biologists Karen Otto and Thomas Silhavy found a mechanism bacteria use to sense when they have touched a solid surface, which sets into motion the process for building a film. Their study of E. coli identified a protein on the surface of the bacteria that initiates biofilm formation, plus a two-protein receptor system that receives and transmits the signal within the cell.
"In a sense, you can say that for E. coli this is a touch sensor," said Silhavy, a professor in the Department of Molecular Biology. "If we mutate these genes, the bacteria don't attach as well and, if they do, they attach in a different way."
A paper describing the results is appearing in the Feb. 5 online edition of the Proceedings of the National Academy of Sciences.
The results suggest that disrupting this sensing mechanism may be an effective strategy for developers of drugs or other antibacterial agents aimed specifically at biofilms. When bacteria join together as a biofilm, they become much more resistant to antibiotics than when they were free-floating, said Silhavy.
Many kinds of bacteria commonly found in liquid environments naturally form biofilms when they meet a solid surface. Biofilms often occur on teeth where, if not removed, they become part of plaque and lead to decay. They also can pose a problem on any artificial surface implanted in the body, such as prosthetics and catheters, which can be difficult to treat with antibiotics. Biofilms corrode pipes, infect heating and cooling devices and slow down ships by making the hulls move less smoothly through the water.
Otto, a postdoctoral researcher in Silhavy's lab, used a variety of techniques to pinpoint the touch-sensing mechanism. First, she created a strain of bacteria with an easily detectable
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