title: Cooxidation of naphthalene and other polycyclic aromatic hydrocarbons by the nitrifying bacterium, Nitrosomonas europaea.
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 microM 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 microM) 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.
authors.affiliation: Department of Civil and Environmental Engineering, Kyonggi University, Suwon City, Korea. swchang@kuic.kyonggi.ac.kr
authors.forename: Soon W
authors.initials: SW
authors.lastname: Chang
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hyman
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Williamson
mesh_terms: D000114:Acetylene / Q000494:pharmacology; D000641:Ammonia / Q000378:metabolism; D001667:Binding, Competitive; D001673:Biodegradation, Environmental; D007700:Kinetics; D009281:Naphthalenes / Q000378:metabolism* / Q000494:pharmacology; D043370:Nitrosomonas europaea / Q000378:metabolism*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D009281:Naphthalenes; D011084:Polycyclic Aromatic Hydrocarbons; C031721:naphthalene; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase; D000114:Acetylene; D010100:Oxygen