J Bacteriol, July 1998, p. 3644-3649, Vol. 180, No. 14
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Fakultät für Biologie, Mikrobielle Ökologie, Universität Konstanz, D-78457 Konstanz, Germany
Received 21 January 1998/Accepted 11 May 1998
The denitrifying bacterium Azoarcus anaerobius LuFRes1
grows anaerobically with resorcinol (1,3-dihydroxybenzene) as the sole source of carbon and energy. The anaerobic degradation of this compound
was investigated in cell extracts. Resorcinol reductase, the key enzyme
for resorcinol catabolism in fermenting bacteria, was not present in
this organism. Instead, resorcinol was hydroxylated to
hydroxyhydroquinone (HHQ; 1,2,4-trihydroxybenzene) with nitrate or
K3Fe(CN)6 as the electron acceptor. HHQ was
further oxidized with nitrate to 2-hydroxy-1,4-benzoquinone as
identified by high-pressure liquid chromatography, UV/visible light
spectroscopy, and mass spectroscopy. Average specific activities were
60 mU mg of protein
1 for resorcinol hydroxylation and 150 mU mg of protein
1 for HHQ dehydrogenation. Both
activities were found nearly exclusively in the membrane fraction and
were only barely detectable in extracts of cells grown with benzoate,
indicating that both reactions were specific for resorcinol
degradation. These findings suggest a new strategy of anaerobic
degradation of aromatic compounds involving oxidative steps for
destabilization of the aromatic ring, different from the reductive
dearomatization mechanisms described so far.
This article has been cited by other articles:
| Appl. Environ. Microbiol. | Infect. Immun. | Eukaryot. Cell |
|---|---|---|
| Mol. Cell. Biol. | J. Virol. | Microbiol. Mol. Biol. Rev. |
| ALL ASM JOURNALS |