Abstract
Some plasmid-free Tol- strains derived from Pseudomonas putida PAW1 (which carries the TOL plasmid pWW0) have a segment of TOL DNA located chromosomally. Of three independently isolated strains, PAW86 had an integrated TOL segment of 16 kilobases and PAW85 had two copies of this segment in different chromosomal locations, whereas the chromosomal DNA of PAW82 showed no homology with the TOL plasmid. In cultures of the parental strain, it appears that a 56-kilobase TOL DNA segment is located chromosomally in some cells.