Molecular mechanism of magneto-aerotaxis in bacteria

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Magnetotactic bacteria orient by swimming along magnetic fields lines, which is due to intracellular organelles, the magnetosomes. Although magnetic sensing is generally assumed to facilitate navigation to growth-favoring suboxic zones in their aquatic habitats, possibly by interaction with aerotaxis, its physiological significance has remained poorly understood, and the molecular mechanisms governing complex navigational behaviour in magnetic bacteria are unknown. In the requested project we will study magneto-aerotaxis in the alphaproteobacterium Magnetospirillum gryphiswaldense, which is predicted to have one of the most complex sensoric networks found in a prokaryotic organism. Behavioral responses to defined magnetic and chemical cues will be assessed quantitatively by video microscopy and chemotaxis assays. Genomic identification of determinants for magneto-aerotaxis will be followed by their functional genetic analysis. In particular, we will address the molecular control and cell biology of magnetic swimming polarity. This will lead to an in-depth understanding of the molecular mechanisms of magnetic orientation in organisms and will contribute to an improved knowledge of sensorsy responses in bacteria.