nitrifying bacteria

Anne Heise aheise at ORCHARD.WASHTENAW.CC.MI.US
Fri Sep 12 08:11:03 EST 1997


I tried sending this reply just to Avleen, but it was returned, so here it
is for the whole group.

According to my microbiology text, what the nitrifying bacteria are doing
to get energy from ammonion ions is oxidizing it (removing electrons from
ammonium) and passing those electrons to oxygen.  I'm not sure whether
these electrons are being passed along an electron transport chain, but I
don't know of any pathways where oxygen is an electron acceptor that don't
use an electron transport chain.  So the nitrifying bacteria are just
doing what plant and animal cells do w/ cellular respiration, only they're
not oxidizing organic molecules like sugars, they're oxidizing ammonium.
When the electrons are removed from ammonium you get nitrite; further
oxidize nitrate and you get nitrate.

The book I have close by the terminal I use for e-mail doesn't discuss how
these bacteria synthesize their organic molecules.  Some bacteria will use
organic molecules as carbon skeletons to synthesize their own carbs and
proteins and so on, even though they don't oxidize these molecules for
energy (weird).  It's also possible they use carbon dioxide to make
their multi-carbon molecules.

I bet Brock's book, The Biology of Microorganisms, would have a good and
not-too-turgid discussion of these bacteria.

Anne Heise
Washtenaw Community College
Ann ARbor MI




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