Isolation and characterization of a cyclohexane-metabolizing Xanthobacter sp
An unusual Xanthobacter sp., capable of independent growth on cyclohexane as the sole source of carbon and energy, has been isolated from soil by using classical enrichment techniques. The mean generation time for growth on cyclohexane was 6 h. The microorganisms showed a limited ability to utilize hydrocarbons, with only alicyclic hydrocarbons closely related to cyclohexane supporting growth. Ultrastructural studies indicated the presence of electron-transparent vesicles in the cyclohexane-grown Xanthobacter sp., but the presence of complex intracytoplasmic membranes could not be identified. A soluble inducible enzyme capable of oxidizing cyclohexane was identified in cell extracts. This enzyme has a pH optimum of 6.5, an absolute specificity for NADPH, and a stoichiometric requirement for molecular O/sub 2/ which was consistent with the formation of cyclohexanol. The enzyme showed no activity towards straight chain alkanes and only a limited activity towards unsaturated ring compounds. Enzymatic studies with cell extracts have indicated the main route of metabolism of cyclohexane by this Xanthobacter sp. to proceed via cyclohexane ..-->.. cyclohexanol ..-->.. cyclohexanone ..-->.. 1-oxa-2-oxocycloheptane (epsilon-caprolactone) ..-->.. 6-hydroxyhexanoate (6-hydroxycaproate) ..-->.. ..-->.. adipic acid. Alternative routes involving initial double hydroxylation of the cyclohexane ring may operate fortuitously but are unlikely to represent major pathways for the dissimilation of cyclohexane by this microorganism.
- Research Organization:
- Trent Polytechnic, Nottingham, England
- OSTI ID:
- 6389772
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 49:5; ISSN AEMID
- Country of Publication:
- United States
- Language:
- English
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