How can bacteria move

If the direction is the right one, the flagella will spend more time in the bunched-up state, making a beeline for the attractant. If it strays off course, the concentration of the chemical will decrease, causing the flagella to act independently and the bacterium will switch to random tumbling until an increase in the concentration of the chemical indicates it is again heading in the right direction.

In this way, the bacterium ensures that, on average, it moves towards the attractant. Flagella are thought to be important in some pathological conditions. One example is in cholera, a disease caused by the water-borne bacteria Vibrio cholerae, common in parts of developing countries that have little access to clean drinking water. According to the World Health Organisation, there were 73, reported cases of cholera in the first four months of this year, 1, of them fatal.

In the course of the disease, the bacteria enter the gut and then need to swim against the natural motion of the intestines, towards the gut wall. Once at the wall, they attach and release cholera toxin.

This causes watery diarrhoea, which can be terminal. Figuring out how flagella work could lead to a better understanding of the disease and lead to treatments. Flagella are also interesting to scientists working in the field of nanotechnology.

In its purest form, nanotechnology is the attempt to build functional machines on an unimaginably tiny scale - devices many times smaller than the cells that make up a body. Pathogenic bacteria such as Salmonella deploy this method of mobility when moving along the surface of a human cell in search of a place to dig in. Getting warmer: With no brain to supply motivation, a bacterium instead must rely on chemical cues from its environment to provide an impetus to move. This process, known as chemotaxis, is completely involuntary.

Bacteria simply respond to the tugs and pulls of their environment to take them to useful places. If the chemical cues are right to continue, the bacterium will begin moving on the same path. If not, it will change course, creating a jagged path toward its destination. Like dancers in a performance, these strains cluster together to create swirling patterns of coordinated motion. As soon as the appendages touched down on a surface, motors within the pili activated and pulled on the filament, propelling the cell forward.

But how, exactly, attachment at one end of the pilus engages motors on the other is still a mystery. Burrows notes that one possible mechanism involves a sensory system in the membrane of type IV pili.

Her team previously reported that sensors within the pili membrane can detect the unraveling of its subunits, which happens when microbes attach to a surface.