A novel plasmid pIJB1 possessing a putative 2,4-dichlorophenoxyacetate degradative transposon Tn5530 in Burkholderia cepacia strain 2a

A 102-kb plasmid, pIJB1, was isolated from Burkholderia cepacia strain 2a, which is able to use 2,4-dichlorophenoxyacetate (2,4-D) as a sole carbon source, and a physical map of the plasmid has been established. It was observed that spontaneous loss of a 37-kb fragment of the plasmid after growth in nonselective medium occurred, generating a plasmid of diminished size, pIJB2. The deletion event is concomitant with the loss of the 2,4-D dissimilatory phenotype, indicating that at least some of the 2,4-D degradative genes are on the missing fragment. The missing fragment is flanked by two identical 4.3-kb insertion sequences (IS) and shows a typical composite transposon structure of 41-kb in size, designated Tn5530. The mutant plasmid pIJB2 possesses a single copy of the IS element.