Mutant magnetotactic bacterium, Magnetospirillum magneticum

This is an image of a mutant Magnetospirillum magneticum, a type of magnetotactic bacteria. This class of bacteria produces magnetite magnetic nanoparticles (MNPs), believed to aid their navigation using the Earth's magnetic field to locate areas with optimal oxygen conditions. The cubo-octahedral-shaped MNPs synthesized biologically by Magnetospirillum magneticum are seen clearly along the length of the bacterium in this image. Each bacterium strain produces different MNP shapes unique to its strain. This mutant contains 23 MNPs (the average number is 11.4 ± 3.7). Researchers are in the process of developing mutants with even larger quantities of MNPs for biomedical applications. Through genetic manipulation of the bacterial DNA, the MNPs can be modified to incorporate antibodies on their surface, and would have many technical applications including cancer cell detection and isolation, neuronal drug delivery and improving magnetic resonance imaging (MRI) techniques. This image was obtained using Cryoelectron microscopy, an emerging technique based on electron microscopy. Frozen samples are imaged at cryogenic temperatures allowing the study of bacteria, cell structures, viruses and protein complexes at molecular resolutions.