Mycobacteria Protocols pp 129-144
Electroporation of Mycobacteria
The study of mycobacterial genomes has exploded during the last 10 yr. Initially, no systems were available for the du-ect manipulation of mycobacterial genes in mycobactena, so Escherichia coli was used as the primary cloning host. Several genomic libraries were created (1, 2, 3, 4, 5) in E. coli. Although these proved useful for the ldentification of many protein antigens (6), the use of E coli as a cloning host has several limitations. It is now known that many mycobacterial promoters do not function at all in E. coli; therefore, it is difficult to study the expression and control of mycobacterial genes in such a host. In addition, certain posttranslational modifications of proteins do not take place in E. coli and therefore the antigenicity and properties of proteins expressed in E coli may differ (7, 8, 9).