Researchers from the Gut Health and Food Safety programme have uncovered how the food-borne bacterial pathogen Campylobacter jejuni can change its swimming behaviour to find a location with more food.
Campylobacter is the most common cause of bacterial food-borne illness in the UK, with more than 371,000 cases annually. Earlier this month, GHFS’ Dr Arnoud van Vliet, leader of IFR’s Campylobacter Research Group, spoke on BBC Radio 4′s Face the Facts programme about the problem of Campylobacter in the food chain.
For infection, the bacteria must pass from contaminated food through thick layers of mucus in the gut to get to the cells lining the gut. In these different locations, Campylobacter must find enough food to sustain itself as well as a suitable environment to carry out respiration, the process of generating energy.
Campylobacter has two sorts of systems that couple sensory information to movement: chemotaxis, in response to external stimuli, and energy taxis, which responds to its internal metabolic status.
The researchers developed a new assay to study these taxis systems, using agar gels containing redox indicator dyes. One dye showed where the respiring bacteria were, and hence where food had been used, and another dye showed how the local environment was changed due to respiration (reduction). By inactivating and re-introducing genes thought to be responsible for Campylobacter’s taxis systems (identified using bioinformatics and genome mining), they could measure changes in swimming behaviour, and further explore the interaction between the two systems.
This work demonstrated that in Campylobacter the system controlling swimming towards food overrides the other system, suggesting that the “need to feed” is the foremost concern for Campylobacter. Campylobacter has a whole range of systems that can detect different chemicals in the environment, and alter swimming behaviour accordingly; the ‘Sat Nav’ of the bacterial world.
Discovering how these ‘Sat Nav’ systems help target the bugs to the site of infection may help prevent future disease, and may be relevant to other food-borne and gut-associated pathogens.
The work is published in the journal PLOS ONE. The Institute of Food Research, which is strategically funded by the Biotechnology and Biological Sciences Research Council, has a research team dedicated to studying Campylobacter as part of the Food Safety Theme of the GHFS Programme. They are looking at what makes Campylobacter such a successful pathogen and to find weaknesses in its biology that could lead to new ways of controlling it.
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