Sticking together makes bacteria nearly invincible
corrode metals and gunk up infrastructure. Despite the scale of the problem, it has drawn little attention. One reason is that biofilms are comparatively poorly understood.
Several different species of bacteria can unite in a single biofilm, which makes it harder to create accurate models in a lab. All the same, progress is being made. A better understanding of biofilms is indicating ways to get rid of them.
No two biofilms are exactly alike. But they begin when a bacterium finds its way to a surface, often attracted by food. It secretes sticky compounds to attach itself and begins to divide.
Within a couple of days—or a few hours, for the fastest-reproducing strains—a small colony of descendants has formed. The new bacteria, and any interested passers-by, can attach themselves to the colony in several ways. These include polymers secreted by the bacteria.
Molecules of DNA usually carry the organism’s genetic information, but bacteria can repurpose them as biochemical glue. In a paper published in Nature Communications in April, Tiago Costa, a bacteriologist at Imperial College London, reported that conjugative pili, hair-like filaments that bacteria use to exchange genetic information, can likewise be repurposed to bind them together. The bacteria can also build barricades from other chemicals they find in their environment.
Biofilms in living bodies, for instance, can sometimes exploit their host’s immune system. When white blood cells spot a bacterial infection, they sometimes release strings of extracellular DNA to cordon it off. But that often backfires, helping bind the biofilm together.
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