Xer Site-Specific Recombination, an Efficient Tool To Introduce Unmarked Deletions into Mycobacteria

Genetic manipulation of mycobacteria still represents a serious challenge due to the lack of tools and selection markers. In this report, we describe the development of an intrinsically unstable excisable cassette for introduction of unmarked mutations in both Mycobacterium smegmatis and Mycobacterium tuberculosis.