Figure 5. Mutants in dhb genes are defective in bacillibactin (BB) synthesis.

A. Production of BB starts with chorismate and proceeds through the enzymatic activities of the DhbC, DhbB, and DhbA proteins to DHB, an intermediate with weak siderophore activity. DHB is subsequently activated by DhbE-mediated adenylation. A modular peptide synthetase later modifies the resulting 2, 3-dihydroxy-benzoyl-adenylate through the addition of glycine and threonine residues and finally esterifies three of these intermediates to form BB; B. Wild-type, dhbE, dhbF and dhbA strains were plated on CAS hard agar plates (Materials and Methods). Photographs were taken after 48 hours of incubation at room temperature. The results are representative of five independent experiments.