Nitrite elimination and hydrolytic ring cleavage in 2,4,6-trinitrophenol (picric acid) degradation.

Two hydrogenation reactions in the initial steps of degradation of 2,4,6-trinitrophenol produce the dihydride Meisenheimer complex of 2,4,6-trinitrophenol. The npdH gene (contained in the npd gene cluster of the 2,4,6-trinitrophenol-degrading strain Rhodococcus opacus HL PM-1) was shown here to encode a tautomerase, catalyzing a proton shift between the aci-nitro and the nitro forms of the dihydride Meisenheimer complex of 2,4,6-trinitrophenol. An enzyme (which eliminated nitrite from the aci-nitro form but not the nitro form of the dihydride complex of 2,4,6-trinitrophenol) was purified from the 2,4,6-trinitrophenol-degrading strain Nocardioides simplex FJ2-1A.

NpdR, a repressor involved in 2,4,6-trinitrophenol degradation in Rhodococcus opacus HL PM-1.

Rhodococcus opacus HL PM-1 utilizes 2,4,6-trinitrophenol (picric acid) as a sole nitrogen source. The initial attack on picric acid occurs through two hydrogenation reactions. Hydride transferase II (encoded by npdI) and hydride transferase I (encoded by npdC) are responsible for the hydride transfers.

Homologous npdGI genes in 2,4-dinitrophenol- and 4-nitrophenol-degrading Rhodococcus spp.

Rhodococcus (opacus) erythropolis HL PM-1 grows on 2,4,6-trinitrophenol or 2,4-dinitrophenol (2,4-DNP) as a sole nitrogen source. The NADPH-dependent F(420) reductase (NDFR; encoded by npdG) and the hydride transferase II (HTII; encoded by npdI) of the strain were previously shown to convert both nitrophenols to their respective hydride Meisenheimer complexes. In the present study, npdG and npdI were amplified from six 2,4-DNP degrading Rhodococcus spp.

Bioelimination of trinitroaromatic compounds: immobilization versus mineralization.

Electron deficiency of trinitroaromatic compounds favors gratuitous reduction of nitro groups or unique ring hydrogenation. From nitro-group reduction of 2,4,6-trinitrotoluene (TNT), some highly reactive products are generated that are subject to further transformation or interaction with diverse electrophiles. Up to now, only initial ring hydrogenation of picric acid (2,4,6-trinitrophenol) opens perspectives of complete degradation.

npd gene functions of Rhodococcus (opacus) erythropolis HL PM-1 in the initial steps of 2,4,6-trinitrophenol degradation.

Rhodococcus (opacus) erythropolis HL PM-1 grows on 2,4,6-trinitrophenol (picric acid) or 2,4-dinitrophenol (2,4-DNP) as sole nitrogen source. A gene cluster involved in picric acid degradation was recently identified. The functional assignment of three of its genes, npdC, npdG and npdI, and the tentative functional assignment of a fourth one, npdH, is reported.

Analysis of a new dimeric extradiol dioxygenase from a naphthalenesulfonate-degrading sphingomonad.

A new extradiol dioxygenase was cloned by screening a gene bank from the naphthalenesulfonate-degrading bacterial strain BN6 for colonies with 2,3-dihydroxybiphenyl dioxygenase (DHBPDO) activity. A 1.6 kb DNA fragment was sequenced and an ORF of 954 bp identified.