Development of a technique for the isolation of plasmids from food-related pseudomonas fluorescens

Four strains of Pseudomonas fluorescens were prepared for gel electrophoresis by several methods to detect plasmids. The procedure of Anderson and McKay (1981) produced DNA preparations most amenable to gel electrophoresis when compared to the plasmid reference strains E. coli V517 and putlda NAH+. No plasmids were detected in the range of 1.4-35.8 megadaltons in any of the strains of P. fluorescens. Attempts to transform the protease negative strain, RM14, with DNA from the protease positive strains proved to be successful only when the recipient cells were exposed to 1,000 times the reported maximum level of DNA that can be taken up by competent cells. However, plasmid profiles of these transformants showed no evidence of the uptake of a plasmid.