METagenomic screening of deHALOgenase as new tools for chlordecone depollution – MetHalo

Chlordecone (CLD) is an organochlorine pesticide used for decades to fight the banana weevil and responsible now for the large contamination of soils and waters in the Caribbean. CLD is particularly difficult to degrade, and still present in the soils/waters 30 years after its last use. To control and reduce human exposure to CLD, we propose to develop enzymatic bioremediation, an approach based on the use of catalytic enzymes able to degrade organic pollutants. Dehalogenases which can dechlorinate organochlorine molecules appear as promising enzymes for this CLD degradation. The MetHalo project aims to use functional metagenomic screens to identify novel dehalogenases and doing so enlarge the toolbox to fight CLD contamination.
We will screen gene libraries created from various environmental samples: first and foremost samples from CLD contaminated soils and waters of Guadeloupe; second, samples from diverse extreme environments. The use of a cytometry-based sorting procedure will allow to perform the high-throughput sorting of millions of clones for those displaying the ability to dechlorinate a fluorescent indicator. The positive clones, coding dehalogenases, will then be fully characterized, including on CLD and other organochlorines. The expectations of this project are high with 1) the isolation of novel genes coding for enzymes able to detoxify CLD; 2) the description of the degradation scheme for CLD; 3) the production and characterization of CLD degradation products as standard molecules to quantify and better describe the dehalogenation mechanism (toxicity, stability, environmental impact) and 4) a bioremediation solution. In parallel, the project will develop several actions to promote scientific exchange with local populations by increasing awareness on the CLD ecocide, using participatory approaches and the conception of a new serious game. This serious game will be adapted to raise the awareness on pesticide ecocide inside and outside the Caribbean.