Genetic manipulation of Vibrio cholerae by combining natural transformation with FLP recombination.

Even though Vibrio cholerae is a well-known human pathogen, it is also a normal member of aquatic habitats. Within this environment it often forms biofilms on the chitin-containing exoskeleton of crustaceans and their molts. Chitin not only serves as nutrient source but also induces a developmental program called natural competence. Naturally competent bacteria take up free DNA and integrate it into their genome by homologous recombination, thereby becoming naturally transformed. In this study, we made use of the knowledge on the environmental lifestyle of V. cholerae to genetically manipulate its genome. We achieved this by combining the methods of chitin-induced natural transformation and Flp recombination. Using this approach, we disrupted several genes by insertion of FRT-site-flanked antibiotic-resistance cassettes. The cassettes were subsequently excised by induction of the Flp recombinase, which acts on the FRT sites. This method represents a simplified and faster alternative to standard gene deletion techniques, which often depend on bacterial conjugation and the availability of suicide vectors.