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Appl. Environ. Microbiol., Oct 1997, 3872-3877, Vol 63, No. 10
RA Kester, W De Boer and HJ Laanbroek
Peak emissions of NO and N(inf2)O are often observed after wetting of soil.
The reactions to sudden changes in the aeration of cultures of nitrifying
and denitrifying bacteria with respect to NO and N(inf2)O emissions were
compared to obtain more information about the microbiological aspects of
peak emissions. In continuous culture, the nitrifier Nitrosomonas europaea
and the denitrifiers Alcaligenes eutrophus and Pseudomonas stutzeri were
cultured at different levels of aeration (80 to 0% air saturation) and
subjected to changes in aeration. The relative production of NO and
N(inf2)O by N. europaea, as a percentage of the ammonium conversion,
increased from 0.87 and 0.17%, respectively, at 80% air saturation to 2.32
and 0.78%, respectively, at 1% air saturation. At 0% air saturation,
ammonium oxidation and N(inf2)O production ceased but NO production was
enhanced. Coculturing of N. europaea with the nitrite oxidizer Nitrobacter
winogradskyi strongly reduced the relative levels of NO and N(inf2)O
production, probably as an effect of the lowered nitrite concentration.
After lowering the aeration, N. europaea produced large short-lasting peaks
of NO and N(inf2)O emissions in the presence but not in the absence of
nitrite. A. eutrophus and P. stutzeri began to denitrify below 1% air
saturation, with the former accumulating nitrite and N(inf2)O and the
latter reducing nitrate almost completely to N(inf2). Transition of A.
eutrophus and P. stutzeri from 80 to 0% air saturation resulted in
transient maxima of denitrification intermediates. Such transient maxima
were not observed after transition from 1 to 0%. Reduction of nitrate by A.
eutrophus continued 48 h after the onset of the aeration, whereas N(inf2)O
emission by P. stutzeri increased for only a short period. It was concluded
that only in the presence of nitrite are nitrifiers able to dominate the NO
and N(inf2)O emissions of soils shortly after a rainfall event.
Copyright © 1997, American Society for Microbiology
Production of NO and N(inf2)O by Pure Cultures of Nitrifying and Denitrifying Bacteria during Changes in Aeration
Department of Plant-Microorganism Interactions, Centre for Terrestrial Ecology, Netherlands Institute of Ecology, 6666 ZG Heteren, and Department of Microbial Ecology, Centre for Limnology, Netherlands Institute of Ecology, 3631 AC Nieuwersluis, The Netherlands
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