Lol, you're right that the bacteria use oxidation and not opposing magnets. So the answer is not a mirror of the question. What I Like is the intuition of the person asking this question. It's rare I see someone with the intuition to conceptualize that bacteria could use electrical charges in metabolism which is both fundamental to our expanding understanding of biology and was considered heresy by many people at the time this person asked their question on this website. Like this posters question I think good research usually starts with experience and a hunch, then either turns out to be false or turns out to be close but not exactly as predicted. Also it's facinating the unrelated developments in battery technology that integrate the use of magnetite. I'm sure people fine tuning batteries human made or biological batteries (bacterial batteries, earth batteries) could find this modern research useful & inspiring.
http://www.chemistryviews.org/details/ezine/1418709/Multifaceted_Magnetite_Promising_for_Batteries.html