Evaluation of methyl fluoride and dimethyl ether as inhibitors of aerobic methane oxidation

Methyl fluoride (MF) and dimethyl ether (DME) were effective inhibitors of aerobic methanotrophy in a variety of soils. MF and DME blocked consumption of CH₄ as well as the oxidation of ¹⁴CH₄ to ¹⁴CO₂, but neither MF nor DME affected the oxidation of [¹⁴C]methanol or [¹⁴C]formate to ¹⁴CO₂. Cooxidation of ethane and propane by methane-oxidizing soils was also inhibited by MF. Nitrification (ammonia oxidation) in soils was inhibited by both MF and DME. Production of N₂O via nitrification was inhibited by MF; however, MF did not affect N₂O production associated with denitrification. Methanogenesis was partially inhibited by MF but not by DME. Methane oxidation was ∼100-fold more sensitive to MF than was methanogenesis, indicating that an optimum concentration could be employed to selectively block methanotrophy. MF inhibited methane oxidation by cell suspensions of Methylococcus capsulatus; however, DME was a much less effective inhibitor.