Recombination between rRNA operons created most of the ribotype variation observed in the seventh pandemic clone of Vibrio cholerae

The molecular basis of variation in Vibrio cholera ribotypes is investigated in 47 isolates over 33 years through the analysis of specific enzyme markers and the intergenic spacers between the genes for RNA located at the 16S and 23S ribosomal subunits. Results reveal at least eight recombination events and deletion of tandem operons giving rise to a high degree of ribotype variability. Further, the recombination rate is very high as evidenced by the discovery of new ribotypes within the study period.