Functional assembly of bacterial communities with activity for the biodegradation of an organophosphorus pesticide in the rape phyllosphere

Although most pesticides sprayed on terrestrial plants remain on their leaf surfaces, the relationship between leaf-associated microbial populations and pesticide degradation remains unclear. Here we examined changes in the bacterial community composition in the rape phyllosphere after treatment with dichlorvos, an organophosphorus pesticide. Results indicate that the bacterial community showed marked changes after treatment. We evaluated the rate of dichlorvos degradation by a natural microbial community on rape leaves and found that more dichlorvos was degraded on microbial-population-inhabited leaves than on surface-sterilized leaves. Six dichlorvos-degrading bacteria with 16S rRNA gene sequences that are most similar to those of members of the genera Pseudomonas, Xanthomonas, Sphingomonas, Acidovorax, Agrobacterium and Chryseobacterium were isolated from the natural community. We report for the first time that three of these epiphytic bacterial species, from the genera Sphingomonas, Acidovorax and Chryseobacterium, can degrade organophosphorus compounds. Collectively, these results provide direct evidence that bacteria on leaves can degrade organophosphate pesticides, and demonstrate that phyllosphere bacteria have great potential for the bioremediation of pesticides in situ, where the environment is hostile to nonepiphytic bacteria.