The hostess says, “Hold on there. We don’t allow bacteria in this fine establishment.” The bacterium says, “It’s okay…I’m staph!” It’s a stupid joke, I know, but at least the beginning isn’t scientifically inaccurate. It turns out that some bacteria can, indeed, walk!
Microbiologists have already shown that bacteria can swim through liquid using their amazingly well-designed flagella. They have also found that bacteria can crawl along a surface. However, no one had ever caught them in the act of walking until a team of UCLA researchers started studying the dynamics of bacterial biofilms.
The researchers were studying Pseudomonas aeruginosa, a species of bacterium found in soil, water, and many human-made environments. It can cause lung, skin, eye, and gastrointestinal infections. Like many bacteria, members of the species can exist as either free-swimming individuals or surface-clinging colonies. The surface-clinging colonies form biofilms.
Interestingly enough, a free-swimming bacterium can be genetically identical to a member of a biofilm. However, because the two different lifestyles have different requirements, some genes are active in the free-swimming bacteria but not in the biofilm bacteria, and vice-versa. This switching on and off of genes produces bacteria that look and behave quite different, even though they have the same genome.