FIG. 1.

Characterization of Δfur mutant. (A) PCR analysis of Δfur mutant. The fur gene is depicted with flanking sequences and locations of primers used in PCR analysis. Shown beneath is the extent of sequences carried on the deletion plasmid construct. The primer pairs as shown were used to generate PCR products from Schu S4, GR201 (deletion plasmid integrant derivative), GR203 (Δfur), and GR204 (fur⁺ derivative). “M” indicates lanes with the 1-kb DNA ladder (Invitrogen). (B) Siderophore activity in Δfur mutant and complementation. Schu S4 and GR203 and transformants harboring the control vector pFNLTP6 or the fur⁺ plasmid pGIR461 were grown overnight in iron-replete CDM, and the specific CAS activities of culture supernatants were determined. Assays were carried out in triplicate, and the averages with standard deviations are represented.