Cyclohexane is a natural constituent of crude petroleum. Petroleum products occur naturally or are released into the environment as industrial wastes or sometimes released accidently.
Rouviere P. E. and Chen M. W. (2003) have isolated a bacterial strain, belonging to the class of beta-proteobacteria - Brachymonas petroleovorans CHX. This bacterium is capable of using cyclohexane as a carbon source for its growth. Brzostowicz et al. (2005) have identified two gene clusters in the above bacterium that are induced in presence of cyclohexane and are involved in cyclohexane metabolism. One gene cluster encodes enzymes involved in oxidation of cyclohexane to cyclohexanol. The enzyme catalyzing this reaction is found to be homologous to butane monooxygenase, encoded by the bmo gene operon, whose nucleotide sequence is reported (Sluis et al., 2002). The second larger cluster of genes encodes all the enzymes required for oxidation of cyclohexanol to adipate. Bacteria, such as Acinetobacter sp. NCIB 9871 and Rhodococcus globerulus CL1, are also known to grow on Cycloxanol. It is suggested that adipate continues to be degraded into carbon dioxide by a beta-oxidation process. A similar pathway showing cyclohexanol degradation is also illustrated in the KEGG database.
The following is a text-format of cyclohexane degradation 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 (10k) format.
Cyclohexane Brachymonas petroleovorans CHX | | | butane monooxygenase | | v Cyclohexanol | | | cyclohexanol dehydrogenase | | v from the Cyclohexanone <-------- Cyclohexylsulfamate | Pathway | | cyclohexanone 1,2-monooxygenase | | v 1-Oxa-2-oxocycloheptane | | | 1-oxa-2-oxocycloheptane lactonase | | v 6-Hydroxyhexanoate | | | 6-hydroxyhexanoate dehydrogenase | | V from the 6-Oxohexanoate <--- Caprolactam | Pathway | | 6-oxohexanoate dehydrogenase | | V Adipate | | | adipate-CoA ligase | | V Adipyl-CoA | | | adipyl-CoA dehydrogenase | | V from the 5-Carboxy-2-pentenoyl-CoA <------ Phenylacetate | Pathway | | enoyl-CoA hydratase | | v (3S)-3-Hydroxyadipyl-CoA | | | 3-hydroxyacyl-CoA dehydrogenase | | v 3-Oxoadipyl-CoA | | | | | v to the Nitrophenol Pathway
Page Author(s): Michelle Wagner, Jian Ma and Yogesh Kale
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