Temperature-Sensitive R Plasmid Obtained from Naturally Isolated Drug-Resistant Vibrio cholerae (Biotype El Tor)

A temperature-sensitive fi(-) R plasmid, pJY1, which confers resistance to chloramphenicol, streptomycin, and sulfonamide, was found in a drug-resistant strain of Vibrio cholerae (biotype El Tor) isolated in the Philippines in 1973. The R plasmid is temperature sensitive for transferability but not for stability in the hosts. pJY1 is stably maintained either in V. cholerae or in Escherichia coli at a range of culture temperatures from 27 to 42 degrees C. Compatibility tests with reference R plasmids revealed that pJY1 belongs to the J group. Growth of V. cholerae carrying pJY1 is poor on TCBS (thiosulfate-citrate-bile-sucrose) selective plates when the microbe is subcultured in nutrient broth at temperatures higher than 37 degrees C.