Cooxidation of naphthalene and other polycyclic aromatic hydrocarbons by the nitrifying bacterium,Nitrosomonas europaea |
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Authors: | Chang Soon W Hyman Michael R Williamson Kenneth J |
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Affiliation: | (1) Department of Civil and Environmental Engineering, Kyonggi University, Suwon City, Korea;(2) Department of Microbiology, North Carolina State University, Raleigh, North Carolina 27695, USA;(3) Department of Civil, Construction, and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA |
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Abstract: | The soil nitrifying bacterium Nitrosomonas europaea has shown the ability to transform cometabolically naphthalene as well as other 2- and 3-ringed polycyclic aromatic hydrocarbons (PAHs) to more oxidized products. All of the observed enzymatic reactions were inhibited by acetylene, a selective inhibitor of ammonia monooxygenase (AMO). A strong inhibitory effect of naphthalene on ammonia oxidation by N. europaea was observed. Naphthalene was readily oxidized by N. europaea and 2-naphthol was detected as a major product (85%) of naphthalene oxidation. The maximum naphthol production rate was 1.65 nmole/mg protein-min in the presence of 240 M naphthalene and 10 mM NH4+. Our results demonstrate that the oxidation between ammonia and naphthalene showed a partial competitive inhibition. The relative ratio of naphthalene and ammonia oxidation, depending on naphthalene concentrations, demonstrated that the naphthalene was oxidized 2200-fold slower than ammonia at lower concentration of naphthalene (15 M) whereas naphthalene was oxidized only 100-fold slower than ammonia oxidation. NH4+- and N2H4-dependent O2 uptake measurement demonstrated irreversible inhibitory effects of the naphthalene and subsequent oxidation products on AMO and HAO activity. |
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Keywords: | ammonia monooxygenase cooxidation naphthalene Nitrosomonas europaea PAHs |
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