J Appl Microbiol. 2002;93(3):463-72.  

Evidence that RDX biodegradation by Rhodococcus strain DN22 is plasmid-borne and
involves a cytochrome p-450.

Coleman NV, Spain JC, Duxbury T.

Department of Microbiology, University of Sydney, Sydney, Australia.
ncoleman@gulf.net

AIMS: To investigate the biodegradation of the explosive compound RDX in
Rhodococcus strain DN22, a bacterium previously isolated for its ability to grow
on RDX as sole nitrogen source. METHODS AND RESULTS: Analysis of the rates of
RDX degradation and nitrite production indicated that 2 mol nitrite were
produced per mole RDX degraded. Cells of strain DN22 had the highest activity
against RDX during the exponential phase and low activity in the stationary
phase. Nitrite production from RDX was inhibited by metyrapone, menadione,
piperonyl butoxide, n-octylamine and carbon monoxide and inducible by
pyrrolidine, pyridine and atrazine. Acridine orange treatment yielded RDX-minus
derivatives of strain DN22 at a curing rate of 1.5% and all of the cured
derivatives had lost a large plasmid. CONCLUSIONS: RDX biodegradation in strain
DN22 appears to involve a plasmid-encoded cytochrome p-450 enzyme. SIGNIFICANCE
AND IMPACT OF THE STUDY: Plasmid-borne RDX degradation genes could potentially
be transferred between bacteria. Our research into RDX metabolism in strain DN22
will facilitate future applications of this bacterium for bioremediation.

PMID: 12174045 [PubMed - indexed for MEDLINE]