Wrage Nicole, Velthof Gerard L, Oenema Oene, Laanbroek Hendrikus J
Department of Environmental Sciences, Wageningen University and Research Centre, The Netherlands.
FEMS Microbiol Ecol. 2004 Jan 1;47(1):13-8. doi: 10.1016/S0168-6496(03)00220-4.
Autotrophic ammonia-oxidizing bacteria produce nitrous oxide (N(2)O) as a by-product of nitrification or as an intermediate of nitrifier denitrification. In soil incubations, acetylene (C(2)H(2)) and large partial pressures of oxygen (O(2)) are used to distinguish between these sources. C(2)H(2) inhibits ammonia oxidation and should therefore inhibit N(2)O production by both nitrification and nitrifier denitrification. O(2) suppresses the reduction pathway of nitrifier denitrification. However, doubts concerning the reliability of C(2)H(2) and O(2) as inhibitors have arisen recently. Therefore, in this study we tested the influence of C(2)H(2) and large partial pressures of O(2) alone and in combination on N(2)O production in pure cultures of the ammonia oxidizers Nitrosomonas europaea and Nitrosospira briensis. C(2)H(2) largely inhibited nitrite production in both ammonia oxidizers and N(2)O production by N. europaea. Surprisingly, it did not affect the N(2)O production in N. briensis. The variable response of ammonia oxidizers to C(2)H(2) might have consequences for the use of C(2)H(2) as an inhibitor of nitrification in soils. Different partial pressures of O(2) ranging from less than 10 kPa O(2) to 100 kPa O(2) were tested for their effectiveness in inhibiting N(2)O production via nitrifier denitrification. The partial pressure of 100 kPa O(2) yielded minimal N(2)O production by both ammonia-oxidizing species and seemed to inhibit N(2)O emission from nitrifier denitrification to a large extent. However, a negative effect of 100 kPa O(2) on ammonia oxidation itself could not be excluded. The applicability of both inhibitors in determining N(2)O production pathways in soils is discussed.
自养氨氧化细菌会产生一氧化二氮（N₂O），作为硝化作用的副产物或硝化反硝化作用的中间产物。在土壤培养中，乙炔（C₂H₂）和高氧分压（O₂）被用于区分这些来源。C₂H₂抑制氨氧化，因此应抑制硝化作用和硝化反硝化作用产生的N₂O。O₂抑制硝化反硝化作用的还原途径。然而，最近人们对C₂H₂和O₂作为抑制剂的可靠性产生了怀疑。因此，在本研究中，我们测试了单独使用C₂H₂和高氧分压以及两者联合使用对氨氧化菌欧洲亚硝化单胞菌和布氏亚硝化螺菌纯培养物中N₂O产生的影响。C₂H₂在很大程度上抑制了两种氨氧化菌中的亚硝酸盐产生以及欧洲亚硝化单胞菌产生的N₂O。令人惊讶的是，它并未影响布氏亚硝化螺菌中N₂O的产生。氨氧化菌对C₂H₂的不同反应可能会影响在土壤中使用C₂H₂作为硝化作用抑制剂。测试了从低于10 kPa O₂到100 kPa O₂的不同氧分压对通过硝化反硝化作用抑制N₂O产生的有效性。100 kPa O₂的氧分压使两种氨氧化菌产生的N₂O最少，并且似乎在很大程度上抑制了硝化反硝化作用产生的N₂O排放。然而，不能排除100 kPa O₂对氨氧化本身的负面影响。讨论了这两种抑制剂在确定土壤中N₂O产生途径方面的适用性。
