Fig. 1

The magnetosome in which magnetotactic bacteria (MTB) biomineralize magnetic crystals is a typical example of a bacterial organelle. a Membrane-bounded magnetosomes contain intracellular magnetic nanoparticles (Fe₃O₄ or Fe₃S₄), with typical ~ 20–150 nm sizes. Magnetic particles within MTB magnetosomes are typically organized into (a) chain-like structure(s) within the cell in order to optimize the cellular magnetic dipole moment. Functions of magnetosomes include magnetoreception [15, 16] and ROS detoxification [17, 18], both of which have been experimentally proven. Additional proposed functions, such as iron storage and sequestration, acting as an electrochemical battery or a gravity sensor, need further testing. b Representative electron micrographs of MTB cells collected in this study. The black arrows indicate magnetosome chains