Aerotactic behaviour of bacteria

Some bacterial species are able to swim towards higher concentration of specific chemical compounds, to reach a more favourable environment. This behaviour is called chemotaxis. Usually, they manage to perform this chemotactic motion by biasing their swimming: they swim slightly longer when they feel a higher concentration of their attractant, and slightly shorter on the contrary.

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With Frédéric Moisy and Harold Auradou, we specifically investigated the chemotactic behaviour of the soil bacteria Burkholderia contaminans in an oxygen gradient (i.e. its aerotaxis). Our experimental set-up allowed for simultaneous measurements of the bacteria behaviour and the oxygen concentration profiles while a band of bacteria travelled along our capillary to follow the moving oxygen gradient. This dynamic experiment, close to real-life conditions, enabled us to quantitatively uncover the scaling of the aerotactic coefficient with the oxygen concentration.

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Adam Gargasson followed up with a thorough study of the chemotactic behaviour of E. coli bacteria in fluid and near surfaces, notably highlighting the lack of chemotaxis on surfaces.