After seeing this hilarious video on Metafilter, I had to look more into these magnetotactic bacteria. I’d never heard of these, and from the video, they look like the bacteria are able to be steered using a magnetic field. Here’s what I’m finding so far.
From this article via the NIH:
Magnetotactic bacteria belonging mainly to Magnetospirillum species produces ferromagnetic crystalline particles consisting of magnetite (Fe3O4) or greigite (Fe3S4). These are called bacterial magnetic particles (BMPs). The BMPs are small in size (50–100 nm) and disperse very well because they are covered with a stable lipid membrane . Magnetoliposomes containing cis-diamminedichloroplatinum (II) (CDDP) prepared using BMPs have also been evaluated for targeting and controlled release of drugs at tumor site. It has been observed from such studies that the capture volume of the magnetoliposomes with BMPs was 1.7 times higher than the ones with artificial magnetic particles. Also, when a rotating magnetic field was applied to these magnetoliposomes, the contents of them were released over 2 hours, suggesting that magnetoliposomes containing CDDP shows antitumor activity and that the controlled release of drugs from magnetoliposomes is possible .
Magnetospirillium, eh? These seem like useful little guys. According to the Wikipedia article on magnetospirillium, they were found in pondwater in 1975.
After searching a little further, I found this article from the journal Microbiological Research on them, which ends up going into an immense amount of detail. There is also an easy read by Sandi Clement, that suggests why this adaptation developed:
Why would these bacteria need a compass? Like many other types of bacteria, magnetotactic bacteria don’t like oxygen very much. They will move away from areas with high oxygen and toward areas with low or no oxygen. In an aquatic environment, the level of oxygen decreases as one moves deeper into the water. So, magnetotactic bacteria like to live in the deeper parts of their aquatic environments. They use their magnetic compass to tell them which way is down.
There’s quite a bit of video with these little bacteria swimming around in response to changes in the magnetic field. This site from Komeili Lab has plenty of great clips, including a cryo-electron tomography scans of a bacterium that displays the structure inside.
Hopefully this offers a bit of perspective on the above video. While I wasn’t able to find any current applications for these bacteria (other than Youtube hilarity), these will be something to watch as the years go by!