Specific Inhibitors of Ammonia Oxidation in Nitrosomonas

Abstract

The following compounds or treatments have been shown to inhibit the oxidation of ammonia, but not the oxidation of hydroxylamine in cells of Nitrosomonas : (i) metal-binding agents such as allylthiourea or potassium cyanide; (ii) compounds such as SKF 525 which interact with cytochrome P-450 of mammalian microsomes; (iii) carbon monoxide; (iv) inhibitors of catalase, peroxidase, and amine oxidases such as thiosemicarbazide, ethylxanthate, and iproniazid, respectively; (v) uncouplers of oxidative phosphorylation such as m -chlorocarbonylcyanidephenylhydrazone; (vi) electron acceptors such as phenazine methosulfate; (vii) compounds such as methanol or N 2 O which react with free radicals; and (viii) illumination with 420 lux (5,000 foot candles) of light.

Responses of the terrestrial ammonia-oxidizing archaeonCa. Nitrososphaera viennensis and the ammonia-oxidizing bacteriumNitrosospira multiformisto nitrification inhibitors

“…There are various nitrification inhibitors available, and some of them have been used in soil management over years in several countries (Trenkel, 1997;Di & Cameron, 2005;Moir et al, 2007;Singh & Verma, 2007). The inhibitory effect of the selected six reagents has been mainly explored on AOB or in some cases also on AOA enrichment cultures (Hooper & Terry, 1973;Powell & Prosser, 1986;Amberger, 1989;Zacherl & Amberger, 1990;Hatzenpichler et al, 2008;Jung et al, 2011;Kim et al, 2012;Mosier et al, 2012a).…”

Nitrogen cycling in coastal marine ecosystems

“…Three inhibitors (nitrapyrin, allylthiourea and chlorate) have been widely used to measure nitri¢cation rates in coastal marine sediments [20,129,136,137]. Inhibitors such as nitrapyrin (also called N-serve) and allylthiourea prevent the oxidation of ammonia to hydroxylamine by inhibiting ammonia monoxygenase, the enzyme catalysing this reaction [138]. The nitri¢cation rate is determined by measuring the di¡erence in ammonium accumulation in the presence and absence of the inhibitor.…”

Tri- and tetramethylhydroquinone as electron donors for ammonia monooxygenase in whole cells of Nitrosomonas europaea

“…The inhibitory effects may have the same cause as those described above for more reactive redox reagents. In all cases epoxypropane synthesis was completely inhibited by 10 /xM allylthiourea, which has the monooxygenase as its only known site of action in N. europaea [14].…”

“…On the contrary, these electron donors tended to have an inhibitory effect. This can be compared with the inhibition of ammonia oxidation by redox reagents, first reported by Hooper and Terry [14] for dichlorophe- Table 1 Rate of epoxypropane production with different electron donors…”