Evolution of the bacterial organelle responsible for magnetotaxis

•Magnetosomes are prokaryotic organelles found in three phyla of Gram-negative bacteria.•About 10 genes are essential for the production of magnetosomes.•The formation of magnetite or greigite is controlled by genetic and environmental factors.•The gene clusters determining the formation of magnetosomes are monophyletic.

There are few examples of protein- and lipid-bounded organelles in bacteria that are encoded by conserved gene clusters and lead to a specific function. The magnetosome chain represents one of these rare examples and is responsible for magnetotaxis in magnetotactic bacteria (MTB), a behavior thought to aid in finding their optimal growth conditions. The origin and evolution of the magnetotaxis is still a matter of debate. Recent breakthroughs in isolation, cultivation, single-cell separation, and whole-genome sequencing have generated abundant data that give new insights into the biodiversity and evolution of MTB.