Indigenous organophosphate-degrading (opd) plasmid pCMS1 of Brevundimonas diminuta is self-transmissible and plays a key role in horizontal mobility of the opd gene

A fosmid library of the 66 kb indigenous organophosphate-degrading (opd) plasmid pCMS1 of Brevundimonas diminuta was tagged with mini-transposon EZTn5 < R6K gamma ori/KAN-2 >, to determine its sequence using transposon-specific primers. The sequence revealed the presence of a number of tra genes suggesting their role in conjugal transfer of pCMS1. Consistent with the presence of the tra genes, the B. diminuta plasmid, pCMS1::tet, generated by replacing the opd gene with opd::tet, served as a donor for transferring pCMS1::tet into recipient strain Pseudomonas putida. The self-transmissibility of the opd-containing plasmid pCMS1 and the existence of identical opd genes on otherwise dissimilar plasmids suggests a probable role of indigenous opd plasmids like pCMS1 in transferring the opd gene among soil bacteria.