title: Regulation of nitrogen metabolism in the nitrate-ammonifying soil bacterium Bacillus vireti and evidence for its ability to grow using N2 O as electron acceptor.
abstract: Bacillus vireti is a nitrate-ammonifying bacterium and a partial denitrifier, reducing NO3 (-) , NO2 (-) , NO and N2 O with NarG, NrfA, CbaA and NosZ respectively. Growth is optimized through successive use of the electron acceptors O2 and NO3 (-) , followed by NO2 (-) , NO and N2 O. Fermentation takes place simultaneously with anaerobic respiration. When grown in batch culture with 5 mM initial NO3 (-) , transcription of nrfA was high and most NO3 (-) was reduced to NH4 (+) . With 20 mM initial NO3 (-) , nrfA transcription was lower and more than 50% of the nitrate was recovered as NO, N2 O and N2 . Analysis of gene transcription patterns and corresponding gas kinetics indicated that O2 and NO2 (-) or NO are main controllers of nrfA, nirB, cbaA and nosZ transcription. This was corroborated by analyses of putative binding regions for specific transcriptional regulators. Furthermore, we demonstrate that N2 O reduction in B. vireti supports growth. The high nosZ transcription but low N2 O production seen at 5 mM NO3 (-) implies that this organism can use N2 O reductase to scavenge N2 O from other organisms in the soil, thus possibly acting as a net sink for N2 O.
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Science, Ås, Norway. daniel.mania@nmbu.no.
authors.forename: Daniel
authors.initials: D
authors.lastname: Mania
authors.affiliation: Laboratory of Microbiology, Department of Biochemistry and Microbiology, University of Ghent, Gent, Belgium.
authors.forename: Kim
authors.initials: K
authors.lastname: Heylen
authors.affiliation: Department of Molecular Cell Biology, Faculty of Earth and Life Science, VU University, Amsterdam, The Netherlands.
authors.forename: Rob J M
authors.initials: RJ
authors.lastname: van Spanning
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Science, Ås, Norway.
authors.forename: Åsa
authors.initials: Å
authors.lastname: Frostegård
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001407:Bacillus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004583:Electrons; D009566:Nitrates / Q000378:metabolism*; D009609:Nitrous Oxide / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D012988:Soil Microbiology
chemical_list: D001426:Bacterial Proteins; D009566:Nitrates; D000641:Ammonia; D010088:Oxidoreductases; D009609:Nitrous Oxide