Characterization of anaerobic bacterial populations putatively involved in the degradation of Chlorine pesticides in mangrove soils of Guadeloupe (Lesser Antilles).

Due to their position at the land-sea interface and their proximity to contaminated agricultural areas, mangroves are ecosystems potentially exposed to chlordecone pollution. This study aims to describe, for the first time, the composition of bacterial communities in mangrove soils and their distribution according to chlordecone contamination. The results revealed marked inter-site heterogeneity in bacterial communities across the three study sites, encompassing both an uncontaminated mangrove (Manche à eau; chlordecone concentrations below the detection limit, <5 g kg-1) and contaminated mangroves (Sarcelle and Petite rivière de Goyave), where soil chlordecone concentrations ranged from <5 to 118.8 g kg-1 along the coastal-to-agricultural transects. Between 60 and 90% of the detected taxa belong to groups involved in the degradation of aromatic compounds, while 5 to 15% correspond to genera associated with nitrification processes. This diversity does not appear to be directly correlated with the presence of chlordecone, suggesting the predominant influence of other environmental factors. Nevertheless, two bacterial genera of interest were identified, Dehalogenimonas and Desulfomonile, known for their involvement in the degradation of aromatic compounds according to the FAPROTAX analysis. Furthermore, functional analysis based on the KEGG database suggests the presence of vitamin B12 biosynthesis pathways in Dehalogenimonas and Desulfomonile (found in coastal areas), as well as in Burkholderia (found in agricultural soils). These results suggest the existence of metabolic potential to intervene in both the chemical and biological processes of chlordecone degradation. Finally, mangroves appear to have purification potential favorable to chlordecone degradation, due to the presence of Dehalogenimonas and several other bacterial genera capable of participating in the chemical and/or biological degradation processes of chlordecone.