According to the article, they oxidize iron to create magnetite, which Wikipedia states (here: http://en.wikipedia.org/wiki/Magnetite http://en.wikipedia.org/wi

According to the article, they oxidize iron to create magnetite, which Wikipedia states (here: http://en.wikipedia.org/wiki/Magnetite http://en.wikipedia.org/wiki/Magnetite) "is the most magnetic of all the naturally occurring minerals on Earth". Sounds like the bacteria are well optimized. :)