Dépôt numérique

Plant exudates promote PCB degradation by a rhodococcal rhizobacteria

Toussaint, Jean-Patrick; Pham, Thi Thanh My; Barriault, Diane et Sylvestre, Michel (2012). Plant exudates promote PCB degradation by a rhodococcal rhizobacteria Applied Microbiology and Biotechnology , vol. 95 , nº 6. pp. 1589-1603. DOI: 10.1007/s00253-011-3824-z.

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Rhodococcus erythropolis U23A is a polychlorinated biphenyl (PCB)-degrading bacterium isolated from the rhizosphere of plants grown on a PCB-contaminated soil. Strain U23A bphA exhibited 99% identity with bphA1 of Rhodococcus globerulus P6. We grew Arabidopsis thaliana in a hydroponic axenic system, collected, and concd. the plant secondary metabolite-contg. root exudates. Strain U23A exhibited a chemotactic response toward these root exudates. In a root colonizing assay, the no. of cells of strain U23A assocd. to the plant roots (5.7 × 105 CFU g-1) was greater than the no. remaining in the surrounding sand (4.5 × 104 CFU g-1). Furthermore, the exudates could support the growth of strain U23A. In a resting cell suspension assay, cells grown in a minimal medium contg. Arabidopsis root exudates as sole growth substrate were able to metabolize 2,3,4'- and 2,3',4-trichlorobiphenyl. However, no significant degrdn. of any of congeners was obsd. for control cells grown on Luria-Bertani medium. Although strain U23A was unable to grow on any of the flavonoids identified in root exudates, biphenyl-induced cells metabolized flavanone, one of the major root exudate components. In addn., when used as co-substrate with sodium acetate, flavanone was as efficient as biphenyl to induce the biphenyl catabolic pathway of strain U23A. Together, these data provide supporting evidence that some rhodococci can live in soil in close assocn. with plant roots and that root exudates can support their growth and trigger their PCB-degrading ability. This suggests that, like the flagellated Gram-neg. bacteria, non-flagellated rhodococci may also play a key role in the degrdn. of persistent pollutants.

Type de document: Article
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Centre: Centre INRS-Institut Armand Frappier
Date de dépôt: 09 mars 2024 18:22
Dernière modification: 09 mars 2024 18:22
URI: https://espace.inrs.ca/id/eprint/14095

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