Identification of Fungal and Bacterial Denitrification Inhibitors Targeting Copper Nitrite Reductase.

The usage of nitrification inhibitors is one of the strategies that reduce or slow down the denitrification process to prevent nitrogen loss to the atmosphere in the form of NO. Directly targeting microbial denitrification could be one of the mitigation strategies; however, until now little efforts have been devoted toward the development of denitrification inhibitors. Here, we have identified small-molecule inhibitors of one of the proteins involved in the fungal denitrification pathway. Specifically, virtual screening was employed to identify the inhibitors of copper-containing nitrite reductase (NirK) of the filamentous fungus . Three series of chemical compounds were identified, out of which compounds belonging to two chemical scaffolds inhibited NirK enzymatic activity in low micromolar ranges. Several compounds also displayed moderate inhibition of fungal denitrification activity in vivo. Evaluation of in vitro activity against NirK from denitrifying bacterium (NirK) and in vivo bacterial denitrification revealed a similar inhibitory profile.