Schematic representation of an upright bacterium
Reading aloud Bacteria can walk upright, US researchers have observed: under certain conditions, the rod-shaped unicellular organisms straighten themselves out of their normally more lying position and move over a surface with the aid of threadlike appendages. They mainly use this type of movement to explore their immediate surroundings. On the other hand, crawling while lying down is more likely to move purposefully in one direction, the scientists conclude. With the help of movement patterns, they hope to better understand how the bacteria collapse into the dreaded biofilms. These microbial communities are difficult to combat with antibiotics and play an important role in, for example, chronic infections. Pseudomonas aeruginosa, the bacterial species now under investigation by researchers, is a well-known and dreaded hospital germ: while microbes rarely cause disease in people with an intact immune system, they can cause infections in patients whose immune systems are already weakened - for example, in wounds Urinary tract or the lungs. The treatment is often tedious and difficult because many antibiotics can not harm the bacterium. One reason for the enormous resistance of the germ is its ability to form biofilms. In such communities, the microbes are protected by a layer of mucus so that they can survive even in disinfectants and hair shampoos.

In the current study, the goal of the scientists was to better understand the origin of these biofilms. Using a microscope, they observed the behavior of Pseudomonas and evaluated the data with the computer.
It turned out that individual Pseudomonas bacteria stand upright on their narrow end before the formation of a biofilm and, as it were, move forward. In this way, they can move quickly and spread on the ground in different directions. The upright walk alternated with a creep, with which the bacteria could not move so fast, but purposefully. Both types of movement help the microbes to migrate over a solid ground and eventually merge into a biofilm, the researchers are convinced.

Incidentally, walking and crawling are not the only modes of movement Pseudomonas controls: The microbes can also swim with the help of their cell appendages, push themselves forward jerkily and swarm out in the group together with other bacteria.

Maxsim Gibiansky (University of California, Los Angeles) et al .: Science, Vol. 330, p. 197 dapd / Meike Simann ad


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