Figure 1. Construction of the dapAX mutation results in DAP dependent growth.

The dapA promoter and open reading frame were deleted by homologous recombination using the plasmid pCVD442 (A). Overnight cultures of the indicated strains (the dapAX mutant supplemented with 400 µg/ml DAP) were serially diluted 10 fold in HIB (no DAP) and plated on HIA with or without DAP and incubated at 26°C for 48 hrs (B).