Deletion mutagenesis of iglA. Panel A. Diagram of steps used to construct an iglA deletion mutant. A fragment of pdpD was joined to iglB and these two fragments were ligated to an EmR-sacB cassette. After transformation the recombinant construct integrated into the F. novicida chromosome. Plating the strain with the integrated fragment on sucrose selected for strains that had undergone an excision of the sacB and neighboring regions. Panel B. PCR confirmation of the deletion of iglA. The small arrows indicate the location of the primers used in the reactions.