Correlation between synthesis variation of 2-alkylquinolones and the antifungal activity of a Burkholderia cepacia strain collection.
Twenty epiphytic and rhizospheric bacterial strains harbouring strong antifungal activities were isolated from the Tunisian environment. This group of bacteria was identified as Burkholderia cepacia genomovar I using 16S rDNA and recA fragment gene sequence analyses for two selected strains and RFLP technique for the eighteen other ones. This identification did not show variability between isolates despite the significant differences in the antifungal activities of their culture supernatant and the organic crude extract against Aspergillus niger and other phytopathogenic fungi. Chromatographic and mass spectrometric analyses of these extracts allowed us to confirm the difference between strains of the group. Their metabolic production showed differences in term of contents and quantities of secreted molecules, particularly those which were identified to be involved in the antifungal activities. Two metabolites, named Bc-255 and Bc-257 secreted by the entire group at different amounts, have been purified and tested separately against A. niger. Bc-255 showed an activity twice as high as those shown by Bc-257. The structural characterization of these two compounds by mass spectrometry and nuclear magnetic resonance spectroscopy allowed their identification as two analogous 2-alkylquinolones with only one difference at the alkyl chain.
Equipe Biopesticides L.P.A.P, Centre de Biotechnologie de Sfax, Université de Sfax, P.O. Box 1177, Sfax, 3018, Tunisie.
Olfa
O
Kilani-Feki
Imen
I
Zouari
Gérald
G
Culioli
Annick
A
Ortalo-Magné
Nabil
N
Zouari
Yves
Y
Blache
Samir
S
Jaoua
D000935:Antifungal Agents / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology*; D001234:Aspergillus niger / Q000187:drug effects / Q000472:pathogenicity; D001483:Base Sequence; D061046:Biological Control Agents; D042602:Burkholderia cepacia complex / Q000235:genetics / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004269:DNA, Bacterial / Q000235:genetics; D005658:Fungi / Q000187:drug effects / Q000472:pathogenicity; D005798:Genes, Bacterial; D015394:Molecular Structure; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D015363:Quinolones / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology*
D000935:Antifungal Agents; D061046:Biological Control Agents; D004269:DNA, Bacterial; D015363:Quinolones