Magnetotactic bacteria produce magnetic crystals within their cells. They use these crystals to orient themselves, but we can use them for drug delivery and medical imaging. Up until now, scientists have only been able to culture bacteria that produce magnetite (iron oxide) crystals. For the first time, Dennis Bazylinski at the University of Nevada and his colleagues have been to grow bacteria that can also produce greigite (iron sulfide) crystals.
Bacteria BW-1 were isolated from deepwater samples in Badwater Basin, Death Valley National Park. They have the genes to make either magnetite or greigite crystals, a useful advantage in the uncertain environment in which it finds itself. Because iron oxides have slightly different properties than iron sulfides, BW-1 may turn out to be more useful than standard magnetotactic bacteria.
Below are some magnetotactic bacteria swirling back and forth as an external magnet is moved (you may need to watch this clip on youtube).