Degradation of chlorinated dibenzofurans and dibenzo-p-dioxins by two types of bacteria having angular dioxygenases with different features.
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 mono- to 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.
Habe
H
H
Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Chung
J S
JS
Lee
J H
JH
Kasuga
K
K
Yoshida
T
T
Nojiri
H
H
Omori
T
T
D000192:Actinomycetales / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins; D001572:Benzofurans / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002713:Chlorine / Q000737:chemistry; D004147:Dioxins / Q000737:chemistry / Q000378:metabolism*; D049308:Dioxygenases; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D008401:Gas Chromatography-Mass Spectrometry; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology*
D001426:Bacterial Proteins; D001572:Benzofurans; D004147:Dioxins; D002713:Chlorine; C023614:dibenzofuran; D010105:Oxygenases; D049308:Dioxygenases; C108434:carbazole 1,9a-dioxygenase; C425526:dibenzofuran 4,4a-dioxygenase; C020887:dibenzo(1,4)dioxin