Mutagenesis of Brucella abortus: comparative efficiency of three transposon delivery systems.

Three transposon-containing 'suicide' plasmids were evaluated for their efficiency in promoting insertional mutagenesis in Brucella abortus. All three plasmids are mobilizable vectors and so were conjugally transferred from mobilizing strains of the donor Escherichia coli. The transposition frequencies were expressed as the ratio of Kmr exconjugants per total recipient cells at the initiation of mating. The pUT/Km-based delivery system, which utilizes a derivative of Tn5, yielded a very high frequency of 2.7 x 10(-5) of transposition in B. abortus. In comparison to previously reported accounts of transposition in B. abortus, both the over thousand-fold higher and more stable number of mutants, makes the pUT/Km system a very useful tool for in vivo transposon mutagenesis of Brucella strains.