Intergeneric conjugal transfer of Escherichia coli/Methylobacterium sp. shuttle vector.

To develop a host-vector system for Methylobacterium sp. using a construct based on a small indigenous methylotrophic plasmid, the E. coli--Methylobacterium sp. shuttle vector pWUBR (12.7 kb, Apr, Tcr) was constructed by joining the E. coli plasmid pBR328 and the cryptic plasmid pWU7 (7.8 kb), isolated from the soil facultative methylotrophic bacterium, Methylobacterium sp. strain M17. Via mobilization by the pDPT51 R plasmid, belonging to the IncP-1 incompatibility group, plasmid pWUBR was transferred into the original host of cryptic plasmid pWU7, strain M17, where a competition between the introduced hybrid plasmid and the indigenous cryptic plasmid took place, and into the plasmidless Methylobacterium sp. strain R2b. The stability of pWUBR in Tcr methylotrophic transconjugants after 25 generations of growth under nonselective conditions was more than 90% in both hosts. The ability to replicate in R2b strain demonstrates that the host spectrum of pWUBR is not restricted to the original host of pWU7 and indicates the possibility to use the present system for other methylotrophs.