The effect of simvastatin on soil ammonia oxidisers

Abstract

The quest to understand and distinguish the contributions of ammonia oxidising archaea (AOA) and ammonia oxidising bacteria (AOB) to nitrification in thesoil has increased the search for compounds that can selectively inhibit either of them. This study isaimed to investigate selective inhibition of AOA, in pure cultures and soil, by simvastatin and to determine the effect of selective inhibition of AOA and AOB on NH3 oxidation activity and growth of AOA and AOB in the soil. In pure cultures, simvastatin selectively inhibited all tested AOA isolates at concentrations between 8 and 100 µM. In soil microcosms incubated with 1 mM of simvastatin at low and high NH3 concentrations for 28 days, simvastatin selectively inhibited AOA but not AOB in pH 6.5 soil.More so, simvastatin is a selective AOA inhibitor in culture and soil. AOA and AOB growth in soil were detected at low and high NH4 + concentration. Therefore, AOA and AOB are more active when competition for NH4 + in the soil is relieved using selective inhibitors