Magnetosymbiosis discovery: new perspectives in magnetotaxis research

Magnetotactic bacteria have been the only known magnetoreceptive microorganisms for decades. Even if the existence of magnetotactic protists was suggested in 1986, this is only 30 years later that magnetotaxis was extended to the domain of Eukaryota, thanks to the characterization of magnetotactic symbiotic assemblies composed of a flagellated protist and bacteria biomineralizing magnetic crystals. Their mutualistic ectosymbiosis relies on a collective magnetotaxis coupled to a hydrogen-based syntrophy. This new form of cooperation challenges our view of magnetic biomineralization in prokaryotes and magnetoreception in eukaryotes. In this review, we present how magnetosymbiosis was discovered and how cooperation functions. Finally, we discuss the future research and the new perspectives such discovery brought to the field of magnetotaxis.