Department of Ecology and Genetics, University of Aarhus, Ny Munkegade, DK-8000, Aarhus C, Denmark.
Microb Ecol. 1990 Jan;19(1):63-72. doi: 10.1007/BF02015054.
Depth distributions of O2 respiration and denitrification activity were studied in 1- to 2-mm thick biofilms from nutrient-rich Danish streams. Acetylene was added to block the reduction of N2O, and micro-profiles of O2 and N2O in the biofilm were measured simultaneously with a polarographic microsensor. The specific activities of the two respiratory processes were calculated from the microprofiles using a one-dimensional diffusion-reaction model. Denitrification only occurred in layers where O2 was absent or present at low concentrations (of a fewμM). Introduction of O2 into deeper layers inhibited denitrification, but the process started immediately after anoxic conditions were reestablished. Denitrification activity was present at greater depth in the biofilm when the NO3 (-) concentration in the overlying water was elevated, and the deepest occurrence of denitrification was apparently determined by the depth penetration of NO3 (-). The denitrification rate within each specific layer was not affected by an increase in NO3 (-) concentration, and the half-saturation concentration (Km) for NO3 (-) therefore considered to be low (<25μM). Addition of 0.2% yeast extract stimulated denitrification only in the uppermost 0.2 mm of the denitrification zone indicating a very efficient utilization of the dissolved organic matter within the upper layers of the biofilm.
在丹麦富营养化溪流的 1-2 毫米厚的生物膜中，研究了 O2 呼吸和反硝化活性的深度分布。添加乙炔以阻断 N2O 的还原，并用极谱微传感器同时测量生物膜中的 O2 和 N2O 微剖面。使用一维扩散-反应模型，根据微剖面计算出两个呼吸过程的比活性。反硝化仅发生在不存在 O2 或 O2 浓度较低（几μM）的层中。将 O2 引入更深的层中会抑制反硝化，但在重新建立缺氧条件后，该过程立即开始。当上层水中的 NO3 (-)浓度升高时，生物膜中反硝化活性出现在更深的位置，而反硝化的最深出现显然由 NO3 (-)的穿透深度决定。每个特定层内的反硝化速率不受 NO3 (-)浓度增加的影响，因此认为 NO3 (-)的半饱和浓度（Km）较低（<25μM）。添加 0.2%酵母提取物仅刺激反硝化区最上层 0.2 毫米处的反硝化作用，表明生物膜上层中溶解有机物的利用率非常高。
