%0 Journal Article %A Bradley, David E. %A Williams, Peter A. %T The TOL Plasmid is Naturally Derepressed for Transfer %D 1982 %J Microbiology, %V 128 %N 12 %P 3019-3024 %@ 1465-2080 %R https://doi.org/10.1099/00221287-128-12-3019 %I Microbiology Society, %X Pseudomonas putida mt-2, formerly known as Pseudomonas arvilla mt-2, which carries the wild-type TOL plasmid, and P. putida strain AC37 carrying TOL, were completely lysed by the pilus-adsorbing plasmid-specific bacteriophages PR4 and PRD1. Pseudomonas putida strain PpS388, also harbouring the plasmid, was not lysed. In a P. putida mt-2 host, TOL transferred 18-fold better on a surface (25 × 10−1 transconjugants per donor h−1) than in liquid; when P. putida PpS388 was the host, however, a frequency of only 23 × 10−4 transconjugants per donor h−1 was obtained. Thus, TOL was derepressed for transfer in P. putida mt-2 and P. putida AC37, but not in P. putida PpS388. Electron microscopy revealed that TOL determined thick (8·5–10 nm diameter) flexible pili in large numbers, suggesting constitutive expression in its derepressed state. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-128-12-3019