GREENEYES

Publiée récemment dans la revue Microbial Pathogenesis, une étude menée par des chercheurs indiens met en évidence une corrélation entre exposition des bactéries telluriques aux pesticides et apparition de multi-résistances aux antibiotiques, et identifie les mécanismes en jeu. La présence de résidus de pesticides dans le sol peut entraîner une modification de la voie métabolique de la flore bactérienne endémique, en particulier des bactéries capables de métaboliser les pesticides pour leurs besoins énergétiques (pseudomonas, bacillus, arthrobacter par exemple)....

de Madeleine Lesage, Centre d'études et de prospective

Résumer de l'article

Impacts of pesticide exposure on the soil microbial flora and cross resistance to antibiotics have not been well documented. Development of antibiotic resistance is a common issue among soil bacteria which are exposing to pesticides continuously at sub-lethal concentration. 

The present study was focused to evaluate the correlation between pesticide exposures and evolution of multi drug resistance among isolates collected from soil applied with insecticides. Twenty five insecticide (Monochrotophos) degrading bacteria were isolated from contaminated agricultural soil. 

The bacterial isolates Bacillus Sps, Bacillus cereus, Bacillus firmus and Bacillus thuringiensis were found to be resistant against chloramphenical, monochrotophos, ampicillin, cefotaxime, streptomycin and tetracycline antibiotics used. 

Involvement of plasmid in drug as well as insecticide resistant was confirmed through plasmid curing among selected bacterial strains. Bacillus Sps (MK-07), Bacillus cereus (MK-11), Bacillus firmus (MK-13) and Bacillus thuringiensis (MK-24) lost their resistant against insecticides and antibiotics once after removal of plasmid by exposing to 2% sodium dodecyl sulphate. 

The plasmid was transformed back to bacteria which produced similar derivatives when cultured in Minimal Salt medium (pH 7.0) supplemented with 0.4% of insecticide. Homology modeling was used to prove that organophosphorus hydrolase and able to metabolize all the antibiotics showed positive interaction with high docking score. 

The present study revealed that persistent of insecticides in the agricultural soil may lead to increasing development of multidrug resistance among soil bacteria.

lien direct : http://www.sciencedirect.com/science/article/pii/S0882401017300918.

Merci à Madeleine (PAM)