The nitrate-ammonifying and nosZ-carrying bacterium Bacillus vireti is a potent source and sink for nitric and nitrous oxide under high nitrate conditions

Environ Microbiol. 2014 Oct;16(10):3196-210. doi: 10.1111/1462-2920.12478. Epub 2014 May 15.


Several Gram-positive bacteria carry genes for anaerobic reduction of NO3(-) via NO2(-) to NH4(+) or gaseous nitrogen compounds, but the processes are understudied for these organisms. Here, we present results from a whole-genome analysis of the soil bacterium Bacillus vireti and a phenotypic characterization of intermediate and end-products, formed under anoxic conditions in the presence of NO3(-). Bacillus vireti has a versatile metabolism. It produces acetate, formate, succinate and lactate from fermentation and performs dissimilatory nitrate reduction via NO2(-) to ammonium (DNRA) using NrfA, while NirB may detoxify NO2(-) in the cytoplasm. Moreover, it produces NO from an unknown source and reduces it via N2O to N2 using two enzymes connected to denitrification: an unusual NO reductase, qCuA Nor encoded by cbaA, and a z-type N2O reductase, encoded by nosZ. In batch cultures, B. vireti reduced all NO3(-) to NO2(-) before the NO2(-) was reduced further. The quantities of all products varied with the initial NO3(-) concentration. With 5 mM NO3(-) , 90% was reduced to NH4 (+) while with ≥ 20 mM NO3(-), 50% was reduced to NO, N2O and N2. This organism is thus an aggressive NO2(-) accumulator and may act as a net source and sink of NO and N2O.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonium Compounds / metabolism
  • Bacillus / genetics
  • Bacillus / metabolism*
  • Denitrification
  • Genome, Bacterial
  • Molecular Sequence Data
  • Nitrates / metabolism*
  • Nitric Oxide / metabolism*
  • Nitrites / metabolism
  • Nitrogen / metabolism
  • Nitrous Oxide / metabolism*
  • Oxidoreductases / genetics


  • Ammonium Compounds
  • Nitrates
  • Nitrites
  • Nitric Oxide
  • Oxidoreductases
  • Nitrous Oxide
  • Nitrogen

Associated data

  • GENBANK/ALAN00000000
  • GENBANK/ALAN01000000