Loss of Antibiotic Resistance Transposons if grown in the absence of Antibiotics

Abstract

In a recent article I have proven F is not a single replicon but co-integrate of two complete replicons – F and R. These two replicons are not allowed to function simultaneously but their individual functional states are stringently controlled by the transposon Tn 1000(5.7 Kb). Besides these two replicons we have previously mentioned the Ent plasmid P307. In 1977 we characterized the antibiotic resistance plasmid pCG86 in ETEC isolated from the stool of a piglet with diarrhoeal disease. The genes for heat-labile enterotoxin and heat-stable enterotoxin were also carried by the same plasmid pCG86. In the year 1975 we received this same bacterial isolate of Carlton Gyles (Department of Veterinary Microbiology and Immunology, University of Guelph, Ontario Canada) from Professor S. Falkow (University of California) who saved the stab at room temperature but without adding antibiotics. The same strain can’t grow in the presence of antibiotics. After the discovery of transposons, I felt the re-interpretation of this heteroduplex molecule formed between pCG86 and Ent P307 is absolutely necessary.