Anthracene is a persistent and toxic polycyclic hydrocarbon used in dyes, wood preservatives, coal tar and insecticides. It is commonly found at sites of gas factory pollution. The compound is considered toxic, but toxicology data specific to anthracene is uncommon, or somewhat conflicting. Dean-Ross et al. (2001) state that anthracene is neither genotoxic nor carcinogenic, but is a threat to the environment because of its toxicity to aquatic life, especially through photo-induced toxicity. Ma, Zhang, and Wong (2003) state that anthracene is a priority pollutant because it is carcinogenic, and may cause aberration and mutation in biological tissues.
Anthracene biodegradation by Gram-negative and Gram-positive bacteria and numerous fungi has been reported (Cerniglia, CE, 1992. Biodegradation of Polycyclic Aromatic Hydrocarbons. Biodegradation, 3: 351-368). This pathway map is limited to bacterial metabolism of anthracene. Pseudomonas spp. strains with plasmids containing genes for naphthalene degradation were found to mineralize anthracene (Sanseverino et al., 1993). Bacteria initiate anthracene degradation by hydroxylation of the aromatic ring to yield cis-1,2-dihydroanthracene-1,2-diol (Evans et al., 1965; Akhtar et al., 1975; Jerina et al., 1976). This intermediate is converted to anthracene-1,2-diol, which is cleaved at the meta position to yield 4-(2-hydroxynaph-3-yl)-2-oxobut-3-enoate (Evans et al., 1965). This compound may spontaneously rearrange to form 6,7-benzocoumarin or be converted to 3-hydroxy-2-naphthoate, from which degradation proceeds through 2,3-dihydroxynaphthalene to phthalate (Annweiler et al., 2000). This pathway has been identified in Gram-negative bacteria (Dean-Ross et al., 2001; Moody et al., 2001). Mycobacterium sp. strain LB501T can degrade 3-hydroxy-2-naphthoate acid through phthalate (van Herwijnen et al., 2003).
The Gram-positive bacteria Rhodococcus sp. and Mycobacterium vanbaalenii PYR-1 (formerly Mycobacterium sp. strain PYR-1) also show ortho cleavage of anthracene-1,2-diol to produce 3-[(Z)-2-carboxyvinyl]-2-napthoate (Dean-Ross et al., 2001; Moody et al., 2001). M. vanbaalenii PYR-1 can produce 1-methoxy-2-hydroxyanthracene from anthracene-1,2-diol, representing a third pathway branch from this intermediate (not shown). In addition to initiating anthracene degradation by 1,2-hydroxylation, M. vanbaalenii PYR-1 can catalyze 9,10-hydroxylation of anthracene to produce anthracene-9,10-dihydrodiol, which is converted to 9,10-dihydroxyanthracene and spontaneously oxidized to 9,10-anthraquinone (Moody et al., 2001).
The following is a text-format bacterial anthracene 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 format.
Graphical map (13k) Graphical map (5k) Anthracene Anthracene Mycobacterium vanbaalenii PYR-1 Mycobacterium vanbaalenii PYR-1 Sphingomonas paucimobilis EPA 505 | Pseudomonas rhodesiae KK1 | Sphingomonas sp. LB 126 | Rhodococcus sp. | anthracene | | 9,10-dioxygenase | naphthalene | | 1,2-dioxygenase | | | v v cis-1,2-Dihydroanthracene-1,2-diol [cis-9,10-Dihydroanthracene-9,10-diol] | | | 1,2-dihydro-1,2-dihydroxy- | cis-9,10-dihydro- | naphthalene dehydrogenase | anthracene-9,10-diol | | dehydrogenase | anthracene-1,2-diol | v 1,2-dioxygenase v Anthracene-1,2-diol ------------------> 3-[(Z)-2-Carboxyvinyl]- 9,10-Anthraquinone | 2-naphthoate | | anthracene-1,2-diol | | 1,2-dioxygenase v | to the v Anthracene (fungal) 4-(2-Hydroxynaph-3-yl)- A Pathway 2-oxobut-3-enoate -------------------------> 6,7-Benzocoumarin | | 4-(2-hydroxynaph-3-yl)- | 2-oxobut-3-enoate | hydratase-aldolase | v 3-Hydroxy-2-naphthoate | | 3-hydroxy-2-napthoate | hydroxylase | v 2,3-Dihydroxynaphthalene <--------------------- from the Bacillus thermoleovorans Hamburg 2 Naphthalene Pathway | | v B | v Phthalate | | | v to the Phthalate Family Pathway
Page Author(s): Robyn Geldner, Mark Fischbach, John Schrom, and Jiun-guo Yu
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