Anaerobic iron uptake by Escherichia coli.

Assimilation and uptake of iron in anaerobic cultures of Escherichia coli were supported by iron supplied as ferrienterobactin, ferrichrome, and ferrous ascorbate; however, as in the aerobic cultures, ferrichrome A was a poor iron source. Albomycin inhibited both aerobically and anaerobically grown cells. The siderophore outer membrane receptor proteins FepA and FhuA were produced under anaerobic iron-deficient conditions. Anaerobic transport of ferrienterobactin and ferrichrome was inhibited by KCN and dinitrophenol. The Km for ferrienterobactin uptake in anaerobically grown cells was 0.8 microM, and the Vmax was 38 pmol/min per mg, compared with 0.1 microM and 80 pmol/min per mg, respectively, in aerobically grown cells.