Genomic Insights into the Origin and Evolution of Magnetotaxis

Various organisms, from bacteria to animals, have the ability to sense the geomagnetic field for orientation and navigation, a behavior known as magnetoreception or magnetotaxis in microorganisms. Magnetotactic bacteria (MTB), a group of microorganisms that biomineralize intracellular, nano-sized magnetic mineral crystals of Fe₃O₄ and/or Fe₃S₄ magnetosomes with their ability to swim along geomagnetic field lines, have proved to be an excellent model to study the mechanism, origin and evolution of magnetotaxis. We have discovered a group of novel draft genomes from uncultivated MTB lineages through metagenomic approaches, which illustrates the unexpectedly genomic diversity of MTB in the domain Bacteria. Phylogenetic and comparative genomic analyses of all available MTB genomes have suggested that magnetotaxis is an ancient physiological trait that has a single common origin with lineage-specific evolution. An evolutionary model of MTB is thus proposed, which shed new light on the origin and evolution of magnetotaxis in the domain Bacteria.