Effect of several nitrification inhibitors on carbon monoxide and methane oxidation by ammonium oxidizers

Abstract

The effects of nine inhibitors of chemolithotrophic nitrification on carbon monoxide, methane, and ammonia oxidation by Nitrosomonas europaea, Nitrosococcus oceanus, and Nitrosomonas sp. 4W30 (a marine isolate) were examined. CH4 and [Formula: see text] oxidation were inhibited to a greater extent than the oxidation of CO. A concentration of 10 μg/mL of N-Serve was sufficient to completely inhibit [Formula: see text] oxidation in all three species, while a concentration of 100 μg/mL was necessary to completely inhibit CO oxidation. The three organisms used in this study showed widely differing susceptibilities to the inhibitors examined. CO and [Formula: see text] oxidation by Nitrosomonas europaea and Nitrosomonas sp. 4W30 were inhibited by >90% in the presence of 100 μg/mL amino-1,2,4-triazole, while Nitrosococcus oceanus was not inhibited. Terrazole at a concentration of 10 μg/mL inhibited carbon monoxide oxidation by Nitrosococcus oceanus 98.9%, while Nitrosomonas europaea and Nitrosomonas sp. 4W30 were only inhibited by 80.2 and 87.1%, respectively. At 100 μg/mL terrazole inhibition was complete. The results of this study emphasize the necessity of careful selection of nitrification inhibitors and concentrations to be used when examining ammonium oxidizers in natural samples. It also indicates that there arc subtle differences in the physiology of ammonium oxidizers that should be taken into consideration when studying the metabolism of these organisms.