Reversion of an ilvB mutation in Pseudomonas aeruginosa in the presence of a derivative of RP1 plasmid.

We have isolated a derivative of RP1, a broad-host-range plasmid, in whose presence the ilvB112 mutation of Pseudomonas aeruginosa strain PU21 reverts at a high frequency. This derivative of RP1 (RP1-ilvB+ complex) may have arisen by a fusion of the P. aeruginosa ilvB gene with RP1 during their co-transfer into strain PU21. The RP1 derivative is not very stable in the PU21 background but it can apparently be stabilized by its integration into the host chromosome, resulting in an Hfr-type donor strain, SP500.