Degradation of phenanthrene and anthracene by Nocardia otitidiscaviarum strain TSH1, a moderately thermophilic bacterium.
OBJECTIVE
The metabolism of phenanthrene and anthracene by a moderate thermophilic Nocardia otitidiscaviarum strain TSH1 was examined.


RESULTS
When strain TSH1 was grown in the presence of anthracene, four metabolites were identified as 1,2-dihydroxy-1,2-dihydroanthracene, 3-(2-carboxyvinyl)naphthalene-2-carboxylic acid, 2,3-dihydroxynaphthalene and benzoic acid using gas chromatography-mass spectrometry (GC-MS), reverse phase-high performance liquid chromatography (RP-HPLC) and thin-layer chromatography (TLC). Degradation studies with phenanthrene revealed 2,2'-diphenic acid, phthalic acid, 4-hydroxyphenylacetic acid, o-hydroxyphenylacetic acid, benzoic acid, a phenanthrene dihydrodiol, 4-[1-hydroxy(2-naphthyl)]-2-oxobut-3-enoic acid and 1-hydroxy-2-naphthoic acid (1H2NA), as detectable metabolites.


CONCLUSIONS
Strain TSH1 initiates phenanthrene degradation via dioxygenation at the C-3 and C-4 or at C-9 and C-10 ring positions. Ortho-cleavage of the 9,10-diol leads to formation of 2,2'-diphenic acid. The 3,4-diol ring is cleaved to form 1H2NA which can subsequently be degraded through o-phthalic acid pathway. Benzoate does not fit in the previously published pathways from mesophiles. Anthracene metabolism seems to start with a dioxygenation at the 1 and 2 positions and ortho-cleavage of the resulting diol. The pathway proceeds probably through 2,3-dicarboxynaphthalene and 2,3-dihydroxynaphthalene. Degradation of 2,3-dihydroxynaphthalene to benzoate and transformation of the later to catechol is a possible route for the further degradation of anthracene.


CONCLUSIONS
For the first time, metabolism of phenanthrene and anthracene in a thermophilic Nocardia strain was investigated.
Zeinali
M
M
Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
Vossoughi
M
M
Ardestani
S K
SK
D000873:Anthracenes / Q000737:chemistry / Q000378:metabolism*; D001565:Benzoates / Q000378:metabolism; D001673:Biodegradation, Environmental; D002396:Catechols / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006358:Hot Temperature; D009615:Nocardia / Q000378:metabolism*; D010084:Oxidation-Reduction; D010616:Phenanthrenes / Q000737:chemistry / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*; D013045:Species Specificity
D000873:Anthracenes; D001565:Benzoates; D002396:Catechols; D010616:Phenanthrenes; D012989:Soil Pollutants; C031181:phenanthrene; C034020:anthracene; C034221:catechol