International audienceThe genetic resources available in an ecosystem are represented in part by the microbial community structure given that not all genes can be found in all prokaryotic species. The importance of the microbial community structure on the functional capacity to degrade chlorinated solvents in soil and groundwater was investigated. A combination of phylogenetic measurements using phylochip microarrays and 16S rDNA cloning and sequencing and functional gene quantification (both DNA and RNA) was used to evaluate the importance of structure on functional analyses. The quantitative PCR (qPCR) and Reverse Transcriptase-qPCR was applied to a range of genes implicated in chlorinated solvent degradation in the environment. The presence of chlorinated solvents induced a relative degree of stress on the microbial community, which was relieved by the chlorinated compound degradation. Certain members of the community were correlated to the degradation capacity while others were inversely correlated, probably due to inhibitory effect of the compounds. This work helps establish the relationship between structure and function at least within the narrow context of chlorinated solvent degradation. And improve the understanding of efficient community for the biodegradation of pollutant