R Factor Transfer in Rhizobium leguminosarum

Department of Genetics, John Innes Institute, Colney Lane, Norwich NOR 70F ABSTRACT SUMMARY: R factors of the compatibility class P were transferred between strains of Escherichia coli K 12 and Rhizobium leguminosarum . These R factors were stable in R. leguminosarum and conferred similar levels of antibiotic resistance to those in the corresponding R + E. coli K 12 hosts, with the exception of carbenicillin resistance which was greatly reduced. Transfer between R. leguminosarum strains was by conjugation and was stimulated by conditions favouring spheroplast formation. R factor mediated recombination could not be demonstrated.