Evidences of Siderophores Synthesis by Grapevine Xylella fastidiosa, Causal Agent of Pierce's Disease, through Instrumental Approaches
Siderophore molecules from grapevine Xylella fastidiosa were investigated. Such metabolites sequester iron, an essential element, from the host, making them a potential factor of pathogenicty. In an iron-limited medium, siderophores were detected in culture plates of X. fastidiosa containing the complex Chromeazurol S (CAS). A combination of different instrumental analyses was used for siderophore(s) characterization, such as: immobilized metal affinity chromatography (IMAC), micelar electrokinetic capillary chromatography (MEKC) and electrospray-mass spectrometry (ESI-MS). The results show that grapevine X. fastidiosa produced siderophore(s), as confirmed by the CAS plate assay. The extraction of the compound(s) using IMAC with immobilized Fe(3+) was important for analyte purification. The chelator was not separated by capillary zone electrophoresis, indicating the possibility of a neutral compound under the investigated pHs. MEKC runs presented a different peak (when compared to the control analysis) which represented a slightly hydrophobic compound. Mass spectrometry showed that the compound(s) may have a relative molecular mass within the expected range for siderophore molecules, such as 875, 1004 and 1092 Da.