Bacteria lead a fast-and-furious social life, forming tenacious biofilms held together by slime. Now it appears that slime use determines the nature of the diseases they cause.
The decision to make slime or not can depend on 鈥渜uorum sensing鈥�, in which bacteria detect how dense the colony is. Carey Nadell at Princeton University and colleagues designed a computer model of biofilms and found that if some bacteria turn off slime production when density is great and focus on reproducing, they can burst out of the biofilm and proliferate. But after a while they are suffocated when the bacteria that kept making slime mount up.
The 鈥渟lime off鈥� strategy is used by cholera bacteria, which cause short, intense gut infections. The 鈥渒eep sliming鈥� strategy is used by Pseudomonas bacteria in the lungs, which form chronic infections. (PLoS Biology, ).
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