To further test our hypothesis that P was solubilized by bacterial
siderophores, we tested wild type of P. fluorescens and two
mutants PchA and PchC. While mutant PchA was completely
impaired in siderophore production mutant PchC was partially
impaired. The wild type (4.4 mg L1) solubilized 2-fold and 4-fold
more P than mutants PchC and PchA, which was consistent with
their ability in siderophore production (Fig. 1).