Degradation of Chlorinated Dibenzofurans and Dibenzo- p -Dioxins by Two Types of Bacteria Having Angular Dioxygenases with Different Features

Abstract

Two kinds of bacteria having different-structured angular dioxygenases-a dibenzofuran (DF)-utilizing bacterium, Terrabacter sp. strain DBF63, and a carbazole (CAR)-utilizing bacterium, Pseudomonas sp. strain CA10-were investigated for their ability to degrade some chlorinated dibenzofurans (CDFs) and chlorinated dibenzo-p-dioxins (CDDs) (or, together, CDF/Ds) using either wild-type strains or recombinant Escherichia coli strains. First, it was shown that CAR 1,9a-dioxygenase (CARDO) catalyzed angular dioxygenation of all monoto triCDF/Ds investigated in this study, but DF 4,4a-dioxygenase (DFDO) did not degrade 2,7-diCDD. Secondly, degradation of CDF/Ds by the sets of three enzymes (angular dioxygenase, extradiol dioxygenase, and meta-cleavage compound hydrolase) was examined, showing that these enzymes in both strains were able to convert 2-CDF to 5-chlorosalicylic acid but not other tested substrates to the corresponding chlorosalicylic acid (CSA) or chlorocatechol (CC). Finally, we tested the potential of both wild-type strains for cooxidation of CDF/Ds and demonstrated that both strains degraded 2-CDF, 2-CDD, and 2,3-diCDD to the corresponding CSA and CC. We investigated the sites for the attack of angular dioxygenases in each CDF/D congener, suggesting the possibility that the angular dioxygenation of 2-CDF, 2-CDD, 2,3-diCDD, and 1,2,3-triCDD (10 ppm each) by both DFDO and CARDO occurred mainly on the nonsubstituted aromatic nuclei.

Aerobic Degradation of Petroleum Components by Microbial Consortia

“…The initial reactions of dibenzofuran and carbazole can be classified into angular and lateral dioxygenation, which may be catalyzed by different enzymes. These enzymes were found in Gram-positive and negative bacteria [138,152,[154][155][156]. Many bacterial strains have the ability to use carbazole as the sole carbon, nitrogen and energy source [150,157].…”

Fungal enzyme production and biodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in contaminated sawmill soil

“…Most of the evidence for aerobic biodegradation of PCDD/Fs has been obtained with lower chlorinated dioxins (Field and Sierra-Alvarez, 2008). Aerobic bacteria from the genera of Sphingomonas, Pseudomonas and Burkholderia have aromatic ring hydroxylating dioxygenase enzymes, but they are usually only able to degrade mono-, di-and trichloro-dibenzo-p-dioxins and -furans (Habe et al, 2001;Nojiri and Omori, 2002) (Figure 5). One exception is the Sphingomonas wittichii strain RW1, which was shown to transform also higher chlorinated dioxins (Nam et al, 2006).…”

“…In addition, 2,3-DCDD and 2,3,7-TriCDD have been degraded with a bacterial P450 from Bacillus megaterium (Sulistyaningdyah et al, 2004). (Bunge et al, 2003), b) 2-CDD by aerobic bacteria (angular dioxygenase) (Habe et al, 2001;Nojiri and Omori, 2002), c) 2,7-DCDD by Phanerochaete chrysosporium (lignin peroxidase) .…”

Methanotrophs: promising bacteria for environmental remediation

“…This bacterium utilizes DCM as a sole source of carbon and energy. An aerobic bacterium was reported to degrade mono-to trichlorinated dioxins with a newly discovered enzyme, an angular dioxygenase known as carbazole 1, 9 a dioxygenase (Habe et al 2001). For characterization of microbial populations, a new screening assay based on quinone profiling (a culture-independent lipid biomarker approach) has been developed for the analyses of in situ microbial populations in dioxin-polluted soils (Hiraishi et al 2001).…”