Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, Baton Rouge, LA 70803, USA.
Water Res. 2010 Apr;44(8):2441-50. doi: 10.1016/j.watres.2010.01.006. Epub 2010 Jan 18.
Fungal and bacterial denitrification rates were determined under a range of redox conditions in sediment from a Louisiana swamp forest used for wastewater treatment. Sediment was incubated in microcosms at 6 Eh levels (-200, -100, 0, +100, +250 and +400 mV) ranging from strongly reducing to moderately oxidizing conditions. Denitrification was determined using the substrate-induced respiration (SIR) inhibition and acetylene inhibition methods. Cycloheximide (C15H23NO4) was used as the fungal inhibitor and streptomycin (C21H39N7O12) as the bacterial inhibitor. At Eh values of +250 mV and +400 mV, denitrification rates by fungi and bacteria were 34.3-35.1% and 1.46-1.59% of total denitrification, respectively, indicating that fungi were responsible for most of the denitrification under aerobic or weakly reducing conditions. On the other hand, at Eh -200 mV, denitrification rates of fungi and bacteria were 17.6% and 64.9% of total denitrification, respectively, indicating that bacteria were responsible for most of the denitrification under strongly reducing conditions. Results show fungal denitrification was dominant under moderately reducing to weakly oxidizing conditions (Eh>+250 mV), whereas bacterial denitrification was dominant under strongly reducing condition (Eh<-100 mV). At Eh values between -100 to +100 mV, denitrification by fungi and bacteria were 37.9-43.2% and 53.0-51.1% of total denitrification, respectively, indicating that both bacteria and fungi contributed significantly to denitrification under these redox conditions. Because N2O is an important gaseous denitrification product in sediment, fungal denitrification could be of greater ecological significance under aerobic or moderately reducing conditions contributing to greenhouse gas emission and global warming potential (GWP).
在路易斯安那沼泽林处理废水的沉积物中，在一系列氧化还原条件下测定了真菌和细菌的反硝化速率。在微环境中，将沉积物在 6 个 Eh 水平（-200、-100、0、+100、+250 和+400 mV）下培养，Eh 水平范围从强还原到中度氧化。使用基质诱导呼吸（SIR）抑制和乙炔抑制方法测定反硝化作用。使用环己酰亚胺（C15H23NO4）作为真菌抑制剂，链霉素（C21H39N7O12）作为细菌抑制剂。在 Eh 值为+250 mV 和+400 mV 时，真菌和细菌的反硝化速率分别为总反硝化作用的 34.3-35.1%和 1.46-1.59%，表明真菌在有氧或弱还原条件下是反硝化作用的主要贡献者。另一方面，在 Eh 值为-200 mV 时，真菌和细菌的反硝化速率分别为总反硝化作用的 17.6%和 64.9%，表明在强还原条件下，细菌是反硝化作用的主要贡献者。结果表明，在中度还原至弱氧化条件下（Eh>+250 mV），真菌反硝化作用占主导地位，而在强还原条件下（Eh<-100 mV），细菌反硝化作用占主导地位。在 Eh 值为-100 至+100 mV 之间，真菌和细菌的反硝化速率分别为总反硝化作用的 37.9-43.2%和 53.0-51.1%，表明在这些氧化还原条件下，真菌和细菌对反硝化作用都有重要贡献。由于 N2O 是沉积物中一种重要的气态反硝化产物，因此在有氧或中度还原条件下，真菌反硝化作用可能具有更大的生态意义，这可能导致温室气体排放和全球变暖潜势（GWP）增加。
