7-Hydroxytropolone produced and utilized as an iron-scavenger by Pseudomonas donghuensis
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Pseudomonas donghuensis can excrete large quantities of iron chelating substances in iron-restricted environments. At least two kinds of iron-chelator can be found in the culture supernatant: fluorescent siderophores pyoverdins, and an ethyl acetate-extractable non-fluorescent substance. The non-fluorescent substance was the dominant contributor to the iron chelating activity of the culture supernatant of P. donghuensis. Electron ionization mass spectrometry, NMR spectroscopy, and IR spectroscopy identified the non-fluorescent iron-chelator as 7-hydroxytropolone. The stoichiometry of 7-hydroxytropolone ferric complex was determined to be 2:1 by the continuous variation method. The production of 7-hydroxytropolone was repressible by iron in the medium. Moreover, the inhibited growth of doubly siderophore-deficient strain of P. donghuensis under iron-limiting conditions could be partly restored by 7-hydroxytropolone. Thus, 7-hydroxytropolone was considered to play a previously undiscovered role as an iron-scavenger for P. donghuensis.
Keywords7-Hydroxytropolone Pseudomonas donghuensis Siderophore 7-Hydroxytropolone ferric complex
We thank Dr Yi Liu, Fenglei Jiang, Zhiling Zhang for analysis of ferric 7-hydroxytropolone complex, and Bo Tang for analysis of NMR spectra of 7-hydroxytropolone.This work was supported by the National Basic Research Program of China (973 Program, No. 2013CB933904), the National Natural Science Foundation of China (21272182, 31570090). This project is partially supported by the Chinese 111 Project Grant B06018, the National Fund for Fostering Talents in Basic Sciences (J1103513), and the Laboratory (Innovative) Research Fund of Wuhan University.
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