| Title : Haloalkane degradation and assimilation by Rhodococcus rhodochrous NCIMB 13064 - Curragh_1994_Microbiology_140 ( Pt 6)_1433 |
| Author(s) : Curragh H , Flynn O , Larkin MJ , Stafford TM , Hamilton JT , Harper DB |
| Ref : Microbiology , 140 ( Pt 6) :1433 , 1994 |
| Abstract : The bacterium Rhodococcus rhodochrous NCIMB 13064, isolated from an industrial site, could use a wide range of 1-haloalkanes as sole carbon source but apparently utilized several different mechanisms simultaneously for assimilation of substrate. Catabolism of 1-chlorobutane occurred mainly by attack at the C-1 atom by a hydrolytic dehalogenase with the formation of butanol which was metabolized via butyric acid. The detection of small amounts of gamma-butyrolactone in the medium suggested that some oxygenase attack at C-4 also occurred, leading to the formation of 4-chlorobutyric acid which subsequently lactonized chemically to gamma-butyrolactone. Although 1-chlorobutane-grown cells exhibited little dehalogenase activity on 1-chloroalkanes with chain lengths above C10, the organism utilized such compounds as growth substrates with the release of chloride. Concomitantly, gamma-butyrolactone accumulated to 1 mM in the culture medium with 1-chlorohexadecane as substrate. Traces of 4-hydroxybutyric acid were also detected. It is suggested that attack on the long-chain chloroalkane is initiated by an oxygenase at the non-halogenated end of the molecule leading to the formation of an omega-chlorofatty acid. This is degraded by beta-oxidation to 4-chlorobutyric acid which is chemically lactonized to gamma-butyrolactone which is only slowly further catabolized via 4-hydroxybutyric acid and succinic acid. However, release of chloride into the medium during growth on long-chain chloroalkanes was insufficient to account for all the halogen present in the substrate. Analysis of the fatty acid composition of 1-chlorohexadecane-grown cells indicated that chlorofatty acids comprised 75% of the total fatty acid content with C14:0, C16:0, C16:1 and C18:1 acids predominating. Thus the incorporation of 16-chlorohexadecanoic acid, the product of oxygenase attack directly into cellular lipid represents a third route of chloroalkane assimilation. This pathway accounts at least in part for the incomplete mineralization of long-chain chloroalkane substrates. This is the first report of the coexistence of a dehalogenase and the ability to incorporate long-chain haloalkanes into the lipid fraction within a single organism and raises important questions regarding the biological treatment of haloalkane containing effluents. |
| ESTHER : Curragh_1994_Microbiology_140 ( Pt 6)_1433 |
| PubMedSearch : Curragh_1994_Microbiology_140 ( Pt 6)_1433 |
| PubMedID: 8081504 |
| Gene_locus related to this paper: rhoso-halo1 |
| Gene_locus related to this paper: rhoso-halo1 |
Curragh H, Flynn O, Larkin MJ, Stafford TM, Hamilton JT, Harper DB (1994)
Haloalkane degradation and assimilation by Rhodococcus rhodochrous NCIMB 13064
Microbiology
140 ( Pt 6) :1433
Curragh H, Flynn O, Larkin MJ, Stafford TM, Hamilton JT, Harper DB (1994)
Microbiology
140 ( Pt 6) :1433