Chlordecone (Kepone®) is a synthetic organochlorine insecticide (C₁₀Cl₁₀O) which was used in the French West Indies to control the banana weevil Cosmopolites sordidus. The toxicity of chlordecone, its remanence in the soil (Cabidoche et al., 2009; Fernàndez-Bayo et al., 2013; Devault et al., 2016) and its presence in fresh (surface or ground) water and seawater has given rise to numerous public health and socioeconomic problems (Dallaire et al., 2012; Kadhel et al., 2014; Multigner et al., 2010 & 2016).

With a view to studying the biodegradability of chlordecone, microbial enrichment cultures have been implemented under anaerobic conditions over a long timeframe.

                                                Chlordecone                          microorganisms                        metabolites

Anaerobic chamber or glove box. © Photo LMP

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The microbiological cultures are monitored by analytical chemistry methods. Gas-phase chromatography - mass spectrometry (GC-MS) at the LCOB laboratory and by high-pressure liquid chromatography - mass spectrometry, Orbitrap (LC-MS) at the LGBM laboratory enabling the various families of metabolites to be monitored. Over the years, a library of chlorine-containing metabolites (80) derived from the degradation of chlordecone has been constituted.

Isolation methods are being developed in order to obtain the principal metabolites at a very high level of purity. Metabolite purification necessitates a variety of methods such as preparatory high-performance liquid chromatography (HPLC) and Combi Flash® Companion® chromatography at the LCOB laboratory.

Out of all the cultures, 2 are particularly interesting since they showed an apparent disappearance of chlordecone over time and accumulation of a principal metabolite with the formula C₉Cl₅H₃.

Metagenomic analysis of the 2 cultures showed the existence of a dozen bacteria (consortium) which transformed chlordecone with 5 species common to the 2 consortia. The bacterial genomes of the consortia are under analysis in order to identify the bacterium or bacteria responsible for the degradation. In addition, we are using the genomic data to attempt to isolate the various bacteria present in the consortia. We recently reported the isolation and the complete genomic sequences of two new Citrobacter isolates that were capable of reproducing chlordecone transformation. Further characterization of these Citrobacter strains should yield deeper insights into the mechanisms involved in this transformation process  (Chaussonnerie et al., 2016).

Lastly, we are attempting to produce certain metabolites by chemical or biological methods in order to purify them, analyze their structures and toxicity, and analyze their degradation.

The research project is part of the "Biodechlord" program (AAP Demichlord) implemented in the context of the National Chlordecone Plan (PNAC) and has received financing from INRA.​

Learn more about the  "Biodechlord" program :

http://fabricemarti8.wixsite.com/biodechlord

Référence : 

Laboratories involved​: ​​

• Laboratory of Metagenomics of Prokaryotes​​
• ​Laboratory​ of ​Organic Chemistry and Biocatalysis​​
  
• Laboratory of genomics and Biochemistry of Metabolism​​