Diversity of chemotactic behaviors in magnetotactic bacteria – MTB-TAXIS

Fluctuations in water level, currents or the activities of living organisms can massively affect the stability of the physico-chemical gradients in aquatic sediments on which many micro-organisms depend. A thin layer of sediment around the oxic-anoxic transition can be particularly affected due to the overlap of reduced and oxidized chemical species. In response to these environmental perturbations, microorganisms, including magnetotactic bacteria (MTB), have developed adaptive strategies to recolonize their optimal growth niche. One of these is based on sophisticated chemotactic systems that relay changes in the environment to direct bacterial movements towards or against physico-chemical gradients. In MTB, these chemotactic behaviors are magnetically assisted by the biomineralization of ferrimagnetic crystals. However, our knowledge of chemotactic responses in MTB and bacteria in general, the diversity of substrates, stimuli and the underlying molecular basis relies solely on the study of a few model organisms in the laboratory. This project will apply a combination of microbiology, microscopy, genomics and bioinformatics approaches at different scales, to decipher the diversity of responses to chemical or gas gradients of electron donors and acceptors. The motility, genome and expression profiles of metabolically and genetically diverse MTB will be characterized under different environmental conditions. An in-depth bioinformatics analysis will then provide a unique collection of new families of proteins and substrates associated with chemotaxis, that will integrate an interactive biocuration system publicly available.