title: The TOL plasmid is naturally derepressed for transfer.
abstract: 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 (2.5 X 10(-1) transconjugants per donor h-1) than in liquid; when P. putida PpS388 was the host, however, a frequency of only 2.3 X 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.
mesh_terms: D001435:Bacteriophages / Q000235:genetics; D003227:Conjugation, Genetic; D010861:Fimbriae, Bacterial / Q000648:ultrastructure; D008854:Microscopy, Electron; D009154:Mutation; D010641:Phenotype; D010957:Plasmids; D011549:Pseudomonas / Q000235:genetics*