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Indian Journal of Biochemistry and Biophysics (IJBB) >
IJBB Vol.41 [2004] >
IJBB Vol.41(5) [October 2004] >
| Title: | o-Phthalic acid, a dead-end product in one of the two pathways of phenanthrene degradation in Pseudomonas sp. strain PP2 |
| Authors: | Krishnan, Samyuktha
Prabhu, Yogikala
Phale, Prashant S |
| Keywords: | Pseudomonas sp. strain PP2
phenanthrene metabolism
1, 2-dihydroxynaphthalene
o-phthalic acid
1-hydroxy-2-naphthoic acid dioxygenase |
| Issue Date: | Oct-2004 |
| Publisher: | CSIR |
| IPC Code: | C07C 69
80
C07C 15
30 |
| Abstract: | Phenanthrene is degraded via either o-phthalic acid or 1, 2-dihydroxynaphthalene in bacteria. A soil isolate Pseudomonas sp. strain PP2 degrades phenanthrene as the sole source of carbon, but failed to utilize naphthalene [Prabhu and Phale (2003) Appl Microbiol Biotechnol 61:342-351]. Analysis of the phenanthrene-grown culture spent media of this strain by gas chromatography-mass spectrometry (GC-MS) showed accumulation of o-phthalic acid. The cell-free extract prepared from this strain showed activity of 1-hydroxy-2-naphthoic acid dioxygenase (1-H-2-NADO). The extract showed conversion of 1-hydroxy-2-naphthoic acid and 2-carboxybenzaldehyde to o-phthalic acid, as analyzed by thin layer chromatography and GC-MS. However, it failed to grow or respire on o-phthalic acid. These results suggest that besides
1, 2-dihydroxynaphthalene pathway, the strain has a truncated o-phthalic acid pathway for phenanthrene metabolism and excretes o-phthalic acid as a dead-end product, indicating the co-existence of two pathways. 1-H-2-NADO, the key enzyme of o-phthalic acid pathway is inducible, has pH optima of 7.5, does not require external addition of Fe(II) as a co-factor and is completely inhibited by 1,10-phenanthroline. Absence of product formation under anaerobic condition and stoichiometric consumption of 0.82 moles of O2 per mole of product formed confirmed the dioxygenase nature of the enzyme. |
| Page(s): | 227-232 |
| ISSN: | 0301-1208 |
| Source: | IJBB Vol.41(5) [October 2004]
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