Figure 7.

Proposed mechanism of iron mobilization from nontronite. Under iron deficient conditions, P. aeruginosa produces pyoverdine that chelates and solubilizes Fe(III) from edge sites of octahedral (O) or tetrahedral (T) sheets. The higher occurrence of tetrahedral Fe(III) sites in NAu-2 facilitates iron mobilization compared to NAu-1. Iron from pyoverdine-Fe³⁺ complexes can be taken up into the bacterial cell to sustain growth. When in direct contact with the mineral particles, P. aeruginosa can acquire iron via a siderophore-independent mechanism.