2,4-Dichloroaniline Pathway Map

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This pathway was contributed by Ike W. Bradlich, University of Minnesota, BioC/MicE 5309. 2,4-Dichloroaniline is a colorless crystalline solid with a characteristic odor. 2,4-Dichloroaniline is used primarily as a dye intermediate, but may also be a found as a biodegradative intermediate of contact type herbicides such as cyclanilide.

Humans exposed to 2,4-Dichloroaniline for relatively short periods of time are subject to slight skin and eye irritation, blue skin, blue lips or finger nails, dizziness, nausea, shortness of breath, confusion, convulsions. Unconsciousness, or abdominal pain. However, humans subjected to prolonged exposure are prone to the formation of methaemoglobin in their blood supply, which effectively reduces the oxygen carrying capacity of the bloodstream and could rapidly result in death. The substance is particularly toxic to aquatic organisms, which is due to the impediment of the 2,4-Dichloroaniline on the oxygen carrying capacity of the blood supply, thus effectively suffocating the aquatic organism.

2,4-Dichloroaniline present in soil biodegrades relatively slowly. However, 2,4-Dichloroaniline (2,4-DCA) does not sorb onto soil particles very well and as a result may leach into the groundwater. The first step of the biodegradation of 2,4-DCA is the dechlorination of 2,4-DCA with a reductive dehalogenase that remove chlorine from the ortho position to form a monochlorinated aniline that can be readily degraded (Struijs & Rogers, 1989). The second step is an oxidative deamination of chloroaniline to chlorocatechol via a modified ortho-cleavage pathway (Zeyer et al., 1985). With chlorinated anilines, a meta cleavage pathway forms dead end products or suicide (highly reactive) products. The dead end products are a result of the narrow substrate specificity of the catabolic enzymes of benzoate, phenol or aniline degrading microbes that are ineffective at degrading chlorinated analogs.

The following is a text-format 2,4-Dichloroaniline pathway map. An organism which can initiate the pathway is given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (10k) format.


               2,4-Dichloroaniline
               anaerobic consortium
                        |
                        | 2,4-dichloroaniline 
                        | reductive
                        | dehalogenase
                        |
                        v
                 4-Chloroaniline
              Moraxella sp. strain G
            Pseudomonas sp. strain JL2
           Aquaspirillum sp. strain 2C 
            Delftia acidovorans CA 28 
            Delftia acidovorans BN3.1
            Comamonas testosteroni I2
        Brevundimonas diminuta INMI KS-7 
                        |
                        |
                        | 4-chloroaniline
                        | dioxygenase 
                        |
                        v
                 4-Chlorocatechol
                        |
                        |
                        |
                        |
                        |
                        V
                     to the
          2,4-Dichlorophenoxyacetic Acid 
                     Pathway

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Page Author: IKE W. Bradlich

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