title: Degradation pathways of phenanthrene by Sinorhizobium sp. C4.
abstract: Sinorhizobium sp. C4 was isolated from a polycyclic aromatic hydrocarbon (PAH)-contaminated site in Hilo, HI, USA. This isolate can utilize phenanthrene as a sole carbon source. Sixteen metabolites of phenanthrene were isolated and identified, and the metabolic map was proposed. Degradation of phenanthrene was initiated by dioxygenation on 1,2- and 3,4-C, where the 3,4-dioxygenation was dominant. Subsequent accumulation of 5,6- and 7,8-benzocoumarins confirmed dioxygenation on multiple positions and extradiol cleavage of corresponding diols. The products were further transformed to 1-hydroxy-2-naphthoic acid and 2-hydroxy-1-naphthoic acid then to naphthalene-1,2-diol. In addition to the typical degradation pathways, intradiol cleavage of phenanthrene-3,4-diol was proposed based on the observation of naphthalene-1,2-dicarboxylic acid. Degradation of naphthalene-1,2-diol proceeded through intradiol cleavage to produce trans-2-carboxycinnamic acid. Phthalic acid, 4,5-dihydroxyphthalic acid, and protocatechuic acid were identified as probable metabolites of trans-2-carboxycinnamic acid, but no trace salicylic acid or its metabolites were found. This is the first detailed study of PAH metabolism by a Sinorhizobium species. The results give a new insight into microbial degradation of PAHs.
authors.affiliation: Department of Molecular Biosciences and Bioengineering, University of Hawaii, 1955 East-West Road, Honolulu, HI 96822, USA.
authors.forename: Young-Soo
authors.initials: YS
authors.lastname: Keum
authors.forename: Jong-Su
authors.initials: JS
authors.lastname: Seo
authors.forename: Yuting
authors.initials: Y
authors.lastname: Hu
authors.forename: Qing X
authors.initials: QX
authors.lastname: Li
mesh_terms: D001673:Biodegradation, Environmental; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D008956:Models, Chemical; D015394:Molecular Structure; D010616:Phenanthrenes / Q000737:chemistry / Q000378:metabolism*; D010795:Phthalic Acids / Q000737:chemistry / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism; D020579:Sinorhizobium / Q000378:metabolism*
chemical_list: D010616:Phenanthrenes; D010795:Phthalic Acids; D011084:Polycyclic Aromatic Hydrocarbons; C031181:phenanthrene; C032279:phthalic acid