Rearrangements in the genomes of Vibrio cholerae strains belonging to different serovars and biovars

The intron-encoded enzyme I-CeuI provides an excellent tool for rapidly examining the organization of genomes of related species of bacteria. Vibrio cholerae strains belonging to serovars O1 and O139 have 9 I-ceuI sites in their genomes, and V. cholerae strains belonging to serovars non-O1 and non-O139 have 10 I-ceuI sites in their genomes. This information can be used as a criterion to differentiate O1 strains from non-O1 and non-O139 strains. To our knowledge, intraspecies variation in the number of rrn operons has not been reported in any other organism. Our data revealed extensive restriction fragment length polymorphism based on a comparison of the I-ceuI digestion profiles of strains belonging to different serovars and biovars. From the analysis of partial digestion products, I-CeuI macrorestriction maps of several classical, El Tor, and O139 strains were constructed. While the linkage maps are conserved within biovars, linkage maps vary substantially between biovars.