Identification of Fungal and Bacterial Denitrification Inhibitors Targeting Copper Nitrite Reductase

Area of Science:

• Biochemistry
• Environmental Microbiology
• Fungal Biology

Background:

• Nitrous oxide (N2O) emissions from soil contribute to atmospheric pollution.
• Nitrification inhibitors are used to reduce nitrogen loss, but direct denitrification inhibitors are underdeveloped.
• Fungal denitrification is a key process in nitrogen cycling and N2O production.

Purpose of the Study:

• To identify small-molecule inhibitors of fungal denitrification.
• To target copper-containing nitrite reductase (FoNirK) from Fusarium oxysporum.
• To evaluate the efficacy of identified inhibitors in vitro and in vivo.

Main Methods:

• Virtual screening of chemical compound libraries.
• In vitro enzymatic assays using purified FoNirK.
• In vivo fungal and bacterial denitrification assays.
• Testing cross-activity against bacterial NirK (AxNirK).

Main Results:

• Identified three series of chemical compounds with inhibitory activity against FoNirK.
• Two chemical scaffolds showed inhibition in the low micromolar range.
• Several compounds demonstrated moderate inhibition of fungal denitrification in vivo.
• Inhibitory profiles were similar for fungal FoNirK and bacterial AxNirK.

Conclusions:

• Small-molecule inhibitors of FoNirK were successfully identified.
• These inhibitors represent a potential strategy for mitigating N2O emissions.
• The findings open avenues for developing targeted denitrification inhibitors for environmental applications.