congresos y reuniones científicas
Pyochelin has antibiotic activity against Xanthomonas axonopodis pv. citri
ADLER CONRADO; SEYEDSAYAMDOST; KOLTER,R; VINCENT PAULA
San Miguel de Tucumán
Congreso; SAIB; 2009
Using a screening method for finding active antibiotics against Xanthomonas axonopodis pv.citri (citrus canker agent), we isolated a bacterial strain capable of inhibiting this plant pathogen growth. After sequencing 16S rDNA and analyzing it using BLAST, we were able to determine genus and speciation. The producing strain, identified as Pseudomonas aeruginosa, secreted the active compound to the supernatant during stationary phase, and its production was prevented if iron was added into the culture medium. In order to purify the compound, the supernatant of a stationary phase culture was run through a C18 cartridge and fractions with different methanol/water solutions were collected. The 40% fraction containing the active compound was analyzed with a LC/MS. The UV spectrum and mass data (324Da) corresponded with the siderophore pyochelin. After HPLC purification using a 40-100% Acetonitrile/water 0.1% formic acid, NMR analysis confirmed the chemical nature of the siderophore. Even though there is literature evidence of siderophore interchangeability, pyochelin is acting in our assays as an antimicrobial in an iron-independent manner. The action mechanism, as an antimicrobial agent, and uptake-efflux transporters involved are part of our research goals. This represents an important finding due to the potential use of pyochelin producing bacteria in citrus canker biocontrol.