FIGURE 7.

Bacterial iron transport in nodules in situ and in isolated bacteroids. A, roots with attached nodules incited by either the wild type strain (closed circles) or feoA(E40K) strain (open triangles) were incubated with 5 μm ⁵⁵Fe²⁺ at time 0. At each time point, root with attached nodules was harvested, and the radiolabel from isolated bacteroids was counted. B, bacteroids were isolated from nodules incited by either the wild type strain (closed circles) or feoA(E40K) strain (open triangles) and were resuspended in assay medium. At time 0, 25 nm ⁵⁵Fe²⁺ was added to the assay medium, and aliquots were subsequently taken at various time points and counted. C, wild type strain grown in modified GSY medium supplemented with 100 nm heme (closed circles) or bacteroids isolated from nodules incited by the wild type strain (open squares) were suspended in assay medium. At time 0, 1 μm ⁵⁹Fe³⁺ was added to the assay medium, and aliquots were subsequently taken at various time points and counted. Each time point is the average of three biological replicates ± S.D. (error bars).