AUTHOR=Hanson Thomas E., Campbell Barbara J., Kalis Katie M., Campbell Mark A., Klotz Martin G. TITLE=Nitrate ammonification by Nautilia profundicola AmH: experimental evidence consistent with a free hydroxylamine intermediate JOURNAL=Frontiers in Microbiology VOLUME=4 YEAR=2013 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2013.00180 DOI=10.3389/fmicb.2013.00180 ISSN=1664-302X ABSTRACT=
The process of nitrate reduction via nitrite controls the fate and bioavailability of mineral nitrogen within ecosystems; i.e., whether it is retained as ammonium (ammonification) or lost as nitrous oxide or dinitrogen (denitrification). Here, we present experimental evidence for a novel pathway of microbial nitrate reduction, the reverse hydroxylamine:ubiquinone reductase module (reverse-HURM) pathway. Instead of a classical ammonia-forming nitrite reductase that performs a 6 electron-transfer process, the pathway is thought to employ two catalytic redox modules operating in sequence: the reverse-HURM reducing nitrite to hydroxylamine followed by a hydroxylamine reductase that converts hydroxylamine to ammonium. Experiments were performed on