Mobilization of nonconjugative pBR322-derivative plasmids from laboratory strains of Escherichia coli to bacteria isolated from seawater.

Mobilization of derivatives of plasmids pBR322 and pBR325 was shown to occur between Escherichia coli K12 strains in LB-broth at 37 degrees C, provided a mobilizer plasmid (F') was present either together with the nonconjugative plasmid or in a second donor strain. Evidence from restriction endonuclease analysis suggested that the mobilization was facilitated by a transposition phenomenon involving the "gamma-delta" sequence of F'. It was shown that mobilization of a derivative of pBR325 from E. coli K12 to bacteria isolated from seawater occurred in incubations in both LB-broth and filtered seawater and that Pseudomonas sp., Enterobacter aerogenes, Klebsiella oxytoca, E. coli, and Citrobacter amalonaticus isolates were recipient-active.