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 N2O. 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 (FoNirK) of the filamentous fungus Fusarium oxysporum. Three series of chemical compounds were identified, out of which
compounds belonging to two chemical scaffolds inhibited FoNirK 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 Achromobacter xylosoxidans (AxNirK) and in vivo bacterial denitrification
revealed a similar inhibitory profile.