title: Degradation of 4-nitrophenol, 2-chloro-4-nitrophenol, and 2,4-dinitrophenol by Rhodococcus imtechensis strain RKJ300.
abstract: A bacterial strain Rhodococcus imtechensis RKJ300 (= MTCC 7085(T) = JCM 13270(T)) was isolated from pesticide-contaminated soil of Punjab by the enrichment technique on minimal medium containing 4-nitrophenol. Strain RKJ300 is capable of utilizing 4-nitrophenol, 2-chloro-4-nitrophenol, and 2,4-dinitrophenol as sole sources of carbon and energy. The strain involved both oxidative and reductive catabolic mechanisms for initial transformation of these compounds. In the case of 2-chloro-4-nitrophenol, colorimetric analysis indicated that nitrite release was followed by stoichiometric elimination of chloride ions. Experiments using whole cells and cell-free extracts showed chlorohydroquinone and hydroquinone as the intermediates of 2-chloro-4-nitrophenol degradation. This is the first report of degradation on 2-chloro-4-nitrophenol by a bacterium under aerobic condition to the best of our knowledge. However, pathways for degradation of 4-nitrophenol and 2,4-dinitrophenol were similar to those reported in other strains of Rhodococcus. Laboratory-scale soil microcosm studies demonstrated that the organism was capable of degrading a mixture of nitrophenols simultaneously, indicating its applicability toward in situ bioremediation of contaminated sites. The fate of the augmented strain as monitored by the plate-counting method and hybridization technique was found to be fairly stable throughout the period of microcosm experiments.
authors.affiliation: Institute of Microbial Technology, Chandigarh-160036, India.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Ghosh
authors.forename: Meenu
authors.initials: M
authors.lastname: Khurana
authors.forename: Archana
authors.initials: A
authors.lastname: Chauhan
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takeo
authors.forename: Asit K
authors.initials: AK
authors.lastname: Chakraborti
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Jain
mesh_terms: D019297:2,4-Dinitrophenol / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004785:Environmental Pollutants / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D009596:Nitrophenols / Q000737:chemistry / Q000378:metabolism*; D012240:Rhodococcus / Q000145:classification / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D004785:Environmental Pollutants; D009596:Nitrophenols; D019297:2,4-Dinitrophenol; C548837:2-chloro-4-nitrophenol; C024836:4-nitrophenol