DDE Remediation and Degradation - Reviews of Environmental Contamination and Toxicology - page 58

soil. Microflora such as algae and cyanobacteria have been reported to uptake DDT
residues from soil, with the predominant degradation product being DDE for algae
and DDD for the dinitrogen-fixating cyanobacteria (Megharaj et al. 1999, 2000).
Aquatic species not only uptake but also transform DDT, with the order of efficacy
being duckweed > elodea > parrot feather. The transformation was into DDD
(31%-48%) and some DDE (4.6%-7.9%) being formed after 6 d (Gao et al. 2000),
in contrast to upland plants, where the major metabolite is usually DDE.

Cl

Cl Cl

Cl

Cl

DDT dehydrochlorinase DDT 2,3-dioxygenase 1,1,1-Trichloro - 2,2 -

bis(4'-chlorophenyl) ethane
(DDT)

Cl

Cl Cl

Cl Cl

Cl Cl Cl HO Cl

H

H

1,1-Dichloro- 2,2 -
bis(4'-chlorophenyl) ethylene
(DDE)

OH

cis - 2,3-Dihydrodiol DDT

A

cis - 2,3-dihydrodiol
DDT dehydrogenase

DDE dehalogenase

Cl Cl

Cl

Cl H

Cl Cl

Cl HO Cl

Cl Cl

OH

Cl HO Cl

1-Chloro- 2, 2 - bis -
(4'-chlorophenyl) ethylene
(DDMU)

1,1-Dichloro- 2 - (dihydroxy- 4' -
chlorophenyl)- 2 - (4'-chlorophenyl)
ethylene

OH

2,3-Dihydroxy DDT

1,1-dichloro-2-(dihydroxy-4'-
chlorophenyl)-2-(4'-chlorophenyl)-
ethylene 1,2-dioxygenase

2,3-dihydroxy DDT
1,2 dioxygenase

6-oxo-2-hydroxy-7-
(4'-chlorophenyl)-3,8,8-
trichloroocta-2E, 4E, 7-
trienoate hydrolase

Cl

Cl Cl

O −

Cl Cl

Cl Cl

O −

O −

O

O O

Cl Cl O

Cl O

Cl Cl

OH

OH

2-(4'-Chlorophenyl)-3,3-
dichloropropenoate

6-Oxo-2-hydroxy-7-
(4'-chlorophenyl)-3,8,8-
trichloroocta-2Z,4Z-,7-
trienoate

6-Oxo-2-hydroxy-7-
(4'-chlorophenyl)-3,8,8,8-
tetrachloroocta-2Z,4Z-
dienoate

D

B

E

O

O

O −

CH 3

O

O

Cl Cl

Cl

4-Chloroacetophenone 4-Chlorobenzoate

4-Chlorophenylacetate

C

O

4-Chlorobenzal dehyde
dehydrogenase

H

Cl

4-Chlorobenzaldehyde

Fig. 1 Proposed degradation pathways for aerobic degradation of DDT and DDE from the
UMBBD website (http://umbbd.msi.umn.edu/ddt/ddt_map.html). Reproduced from Ellis LBM,
Roe D, Wackett LP 2006, “The University of Minnesota Biocatalysis/Biodegradation Database: The
First Decade,” Nucleic Acids Research 34: D517-D521.