Oxidizing iron bacteria made to work in reverse

Rexmundi

My employer operates a biological water filtration plant. The first stage of filtration has the raw water passing through a filter embedded with bacteria, the processes used here is aerated biological treatment where oxidizing processes (bio-oxidation) are used and the microbes gain energy when they transform the ions from a reduced to an oxidized state.
Specifically in the first filter the bacteria oxidize all ferrous oxide to ferric oxide (Fe^+2 to Fe^+3) which is caught in the filter and when the water moves on to the next stage it is completely free of iron.
The large amount of rust build up in the first filter must be periodically cleansed by backwashing. When water is pumped backward through the filter it comes out with both a very very high concentration of Fe^+3 and a portion of the bacteria population.

What I am looking for is a way to reduce the iron in a sample of this backwash water back to Fe^+2. It has been suggested that perhaps an alternative energy source such as glucose could be added then the sample sealed so the bacteria would use all of oxygen present and create anaerobic conditions. In this environment might the very same bacteria that oxidized the iron begin to reduce it?
If not, are there other suggestions on how to accomplish this?

Rexmundi

If it helps I'll link to an article by Toni A. M. Bridge and D. Barrie Johnson

http://aem.asm.org/cgi/content/abstr...urcetype=HWCIT

This describes the process I'd like to emulate but my bacteria are living in water at about 10 degrees Celsius so are definitely not thermophiles.

ViewsofMars

Curious me, have you heard of Brachybacterium sp Mn32?

Andy Resnick

Interesting article. I only skimmed it, but there does not appear to be a mechanistic explanation for the reaction- what enzymes are involved? Once you know the players in the reaction, you can start to ask how to run the reaction in reverse.

I'd recommend doing a literature search (PubMed is a good place to start) to see if you can identify the reaction. And hie thee to a biochemistry department- someone there would be able to help.