A Comparison of NO and N20 Production by the Autophic Nitrifier Nitrosomonas europaea and the Heterotrophic Nitrifier Alcaligenes faecalis

Authors

Iris C. Anderson, Old Dominion University
Mark Poth
Julie Homstead, Old Dominion University
David J. Burdige, Old Dominion UniversityFollow

Document Type

Article

Publication Date

11-1993

Publication Title

Applied and Environmental Microbiology

Volume

59

Issue

11

Pages

3525-3533

Abstract

Soil microorganisms are important sources of the nitrogen trace gases NO and N₂O for the atmosphere. Present evidence suggests that autotrophic nitrifiers such as Nitrosomonas europaea are the primary producers of NO and N₂O in aerobic soils, whereas denitrifiers such as Pseudomonas spp. or Alcaligenes spp. are responsible for most of the NO and N₂O emissions from anaerobic soils. It has been shown that Alcaligenes faecalis, a bacterium common in both soil and water, is capable of concomitant heterotrophic nitrification and denitrification. This study was undertaken to determine whether heterotrophic nitrification might be as important a source of NO and N₂O as autotrophic nitrification. We compared the responses of N. europaea and A. faecalis to changes in partial O₂ pressure (pO₂) and to the presence of typical nitrification inhibitors. Maximal production of NO and N₂O occurred at low pO₂ values in cultures of both N. europaea (pO₂, 0.3 kPa) and A. faecalis (pO₂, 2 to 4 kPa). With N. europaea most of the NH₄⁺ oxidized was converted to NO₂^-, with NO and N₂O accounting for 2.6 and 1% of the end product, respectively. With A. faecalis maximal production of NO occurred at a pO₂ of 2 kPa, and maximal production of N₂O occurred at a pO₂ of 4 kPa. At these low pO₂ values there was net nitrite consumption. Aerobically, A. faecalis produced approximately the same amount of NO but 10-fold more N₂O per cell than N. europaea did. Typical nitrification inhibitors were far less effective for reducing emissions of NO and N₂O by A. faecalis than for reducing emissions of NO and N₂O by N. europaea. A. faecalis produced much less NO and N₂O under denitrifying conditions than under nitrifying conditions, and the NO produced appeared to result primarily from chemical interactions involving NO₂^- at pH 6.95. Once much of the nitrite was consumed, the NO and N₂O produced were further reduced to N₂. Given the rates of NO and N₂O production reported here, our results suggest that heterotrophic nitrification may be a significant source of N₂O in aerobic to near-anaerobic soils and water.

Original Publication Citation

Anderson, I.C., Poth, M., Homstead, J., & Burdige, D. (1993). A comparison of NO and N₂O production by the autotrophic nitrifier Nitrosomonas europaea and the heterotrophic nitrifier Alcaligenes faecalis. Applied and Environmental Microbiology, 59(11), 3525-3533.

Repository Citation

Anderson, Iris C.; Poth, Mark; Homstead, Julie; and Burdige, David J., "A Comparison of NO and N20 Production by the Autophic Nitrifier Nitrosomonas europaea and the Heterotrophic Nitrifier Alcaligenes faecalis" (1993). OES Faculty Publications. 64.
https://digitalcommons.odu.edu/oeas_fac_pubs/64