TABLE 2.

Effect of Mn2+ and Fe3+ in siderophore production of S. meliloti wild-type strains and fur mutants

S. meliloti strainMean rhizobactin 1021 concn ± SD (nM) of cultures grown ina:
M3Fe50M3M3Mn50M3E100M3E100Mn50
102122 ± 161 ± 658 ± 4120 ± 24144 ± 32
Mf124 ± 878 ± 868 ± 9135 ± 30106 ± 18
24233 ± 4109 ± 1095 ± 10173 ± 18132 ± 30
Mf226 ± 194 ± 1070 ± 20160 ± 42160 ± 38
  • a Concentration of rhizobactin 1021 in the supernatant was estimated under the assumption that 1 mol of the trihydroxamate deferoxamine mesylate is equivalent to 1.5 mol of the dihydroxamate rhizobactin 1021. Results were normalized to an optical density of 1. The data shown are based on three separate experiments.