o-Xylene is a member of the BTEX class of aromatic compounds (benzene, toluene, ethylbenzene, and XYLENES). The major use of o-xylene is in the manufacture of phthalic anhydride. A small amount is also used in solvent applications and to make bactericides, soybean herbicides and lubricating oils.
Jorgensen et al. (1995) report, "The oxidation of o-xylene proceeded through o-methylbenzyl alcohol, o-methylbenzaldehyde, and o-methylbenzoate." o-Xylene removal depended on the simultaneous degradation of toluene. Higson and Focht (1992) reported that the degradation of 2-Methylbenzoate was utilized by Burkholderia cepacia MB2. The metabolism from 2-Methylbenzoate to 3-methylcatechol is through a proposed carboxy-hydrodiol compound by dioxygenation. Rhodococcus sp. strain YU6 is able to metabolize o-xylene via direct ring oxidation and meta-cleavage (Jang et al., 2005). The related m-Xylene and p-Xylene degradation pathways are also included in the EAWAG-BBD.
The following is a text-format o-Xylene 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 (14k) format.
o-Xylene o-Xylene
Burkholderia cepacia MB2 Rhodococcus sp. strain YU6
| |
| +--------------+--------------+
| xylene | |
| monooxygenase v o-xylene v o-xylene
| | 3,4-dioxygenase | 4,5-dioxygenase
| | |
v v v
2-Methylbenzyl alcohol 3,4-Dimethylcatechol 4,5-Dimethylcatechol
| | |
| | |
| benzylalcohol | catechol | 4,5-dimethylcatechol
| dehydrogenase | 2,3-dioxygenase | 2,3-dioxygenase
| | |
v v v
2-Methylbenzaldehyde 2-Hydroxy-5-methyl- 2-Hydroxy-4,5-dimethyl-
| 6-oxohepta-2,4-dienoate 6-oxohexa-2,4-dienoate
| | |
| benzaldehyde | |
| dehydrogenase v E v F
| | |
v v v
o-Methylbenzoate CO2 CO2
Burkholderia cepacia MB2
|
|
| toluate dioxygenase
|
|
v
1,2-Dihydroxy-6-methyl-
cyclohexa-3,5-diene-
carboxylate
|
|
| 1,2-dihydroxy-6-methylcyclohexa-
| 3,5-dienecarboxylate dehydrogenase
|
v
3-Methylcatechol
|
|
|
v
to the
Toluene Pathway
Page Author(s): Dong Jun Oh and Michael Turnbull
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