2,4-Dinitrotoluene Pathway Map

2,4-Dinitrotoluene is an industrial compound used in the production of azo dyes, munitions and plastics. Its wide-spread use, and the fact it is a possible carcinogen, mean it is important to understand is microbial degradation to know its propensities for bioremediation. Two identical biodegradation pathways, involving dixoxygenation, nitro group cleavage, and ring cleavage, have been identified in Burkholderia cepacia and Hydrogenophaga palleronii (Johnson et al., 2002).

In an alternative pathway, initiated by Pseudomonas aeruginosa, nitro groups are reduced into amines, potentially ending with 2,4-diaminotoluene (Noguera et al., 1996). Ochrobactrum anthropi and Thielevia sp. can degrade this last compound, but the pathway(s) are not known (Kim et al., 2002). A possible alternative or continuation of this pathway involves acetylation of the amine groups leading to 2,4-diacetamidetoluene (not shown).

The following is a text-format 2,4-dinitrotoluene pathway map. Organisms which can initiate the pathway are 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 (15k) format.

             2,4-Dinitrotoluene                                 2,4-Dinitrotoluene       
          Burkholderia cepacia R34                            Pseudomonas aeruginosa
         Hydrogenophaga palleronii                                     / \                
                     |                                                /   \ 
                     |                                               /     \    
                     | 2,4-dinitrotoluene                  NAD(P)H  /       \  NAD(P)H     
                     | dioxygenase                  nitroreductase /         \ nitroreductase
                     |                                            /           \ 
                     v                                           v             v  
          4-Methyl-5-nitrocatechol                         2-Amino-4-       4-Amino-2-   
                     |                                    nitrotoluene     nitrotoluene 
                     |                                              \       /
                     | 4-methyl-5-nitrocatechol              NAD(P)H \     / NAD(P)H
                     | monooxygenase                  nitroreductase  \   /  nitroreductase
                     |                                                 \ /
                     v                                                  v
	 2-Hydroxy-5-methylquinone                             2,4-Diaminotoluene
                     |                                        Ochrobactrum anthropi 
                     |                                            Thielevia sp.
                     | 2-hydroxy-5-methylquinone                        | 
                     | reductase                                        |
                     |                                                  v A
                     v                                                  |
	  2,4,5-Trihydroxytoluene                                       |       
                     |                                                  v
                     |                                                 CO2
                     | 2,4,5-trihydroxytoluene
                     | dioxygenase
                     |
                     v
      cis,cis-2,4-Dihydroxy-5-methyl-
           6-oxo-2,4-hexadienoate
                     |
                     |
                     | cis,cis-2,4-dihydroxy-5-methyl-
                     | 6-oxo-2,4-hexadienoate hydrolase
                     |
                     v
       Methylmalonate semialdehyde
                     |
                     |
                     | 
                     |
                     v
               Intermediary 
                Metabolism 
                  (KEGG) 

Page Author(s): Jeffrey Flynn and Luke Kane

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