title: Metabolism of 2-chloro-4-nitroaniline via novel aerobic degradation pathway by Rhodococcus sp. strain MB-P1.
abstract: 2-chloro-4-nitroaniline (2-C-4-NA) is used as an intermediate in the manufacture of dyes, pharmaceuticals, corrosion inhibitor and also used in the synthesis of niclosamide, a molluscicide. It is marked as a black-listed substance due to its poor biodegradability. We report biodegradation of 2-C-4-NA and its pathway characterization by Rhodococcus sp. strain MB-P1 under aerobic conditions. The strain MB-P1 utilizes 2-C-4-NA as the sole carbon, nitrogen, and energy source. In the growth medium, the degradation of 2-C-4-NA occurs with the release of nitrite ions, chloride ions, and ammonia. During the resting cell studies, the 2-C-4-NA-induced cells of strain MB-P1 transformed 2-C-4-NA stoichiometrically to 4-amino-3-chlorophenol (4-A-3-CP), which subsequently gets transformed to 6-chlorohydroxyquinol (6-CHQ) metabolite. Enzyme assays by cell-free lysates prepared from 2-C-4-NA-induced MB-P1 cells, demonstrated that the first enzyme in the 2-C-4-NA degradation pathway is a flavin-dependent monooxygenase that catalyzes the stoichiometric removal of nitro group and production of 4-A-3-CP. Oxygen uptake studies on 4-A-3-CP and related anilines by 2-C-4-NA-induced MB-P1 cells demonstrated the involvement of aniline dioxygenase in the second step of 2-C-4-NA degradation. This is the first report showing 2-C-4-NA degradation and elucidation of corresponding metabolic pathway by an aerobic bacterium.
authors.affiliation: Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India.
authors.forename: Fazlurrahman
authors.initials: F
authors.lastname: Khan
authors.forename: Deepika
authors.initials: D
authors.lastname: Pal
authors.forename: Surendra
authors.initials: S
authors.lastname: Vikram
authors.forename: Swaranjit Singh
authors.initials: SS
authors.lastname: Cameotra
mesh_terms: D015082:2,2'-Dipyridyl / Q000378:metabolism; D000332:Aerobiosis / Q000187:drug effects; D000814:Aniline Compounds / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental / Q000187:drug effects; D002244:Carbon / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D049308:Dioxygenases / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D007700:Kinetics; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D009584:Nitrogen / Q000494:pharmacology; D012240:Rhodococcus / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000814:Aniline Compounds; C071396:2-chloro-4-nitroaniline; D015082:2,2'-Dipyridyl; D002244:Carbon; D049308:Dioxygenases; D009584:Nitrogen