Abstract
Streptomycin (SM) resistance detected in Pseudomonas syringae pv. lachrymans was conjugally transmissible to Pseudomonas aeruginosa carrying 36 megadalton (mdal)-RP4 of incompatibility group Pl by mixing culture method. Such transmission of SM resistance was not seen when P. aeruginosa which did not harbor the RP4 was used as the recipient. Transmitted SM resistance of P. aeruginosa was further transmissible to Escherichia coli by conjugation. Agarose gel electrophoretic analysis of plasmid DNA from the transconjugant P. aeruginosa showed a single plasmid DNA of 43.5mdal, which was capable of transforming both P. aeruginosa and E. coil into SM-, Kanamycin (KM)-, Tetracycline (TC)- and Ampicillin (APC)-resistant. From these results, it was suggested that the transfer of SM resistance from P. s. pv. lachrymans to P. aeruginosa and E. coil might be mediated by the 43.5 mdal-plasmid, and that 43.5 mdal-plasmid might be a recombinant plasmid of 7.5 mdal-fragment of SM-resistant gene from chromosome of P. s. pv. lachrymans and 36 mdal-RP4.
