Widespread microbial mercury methylation genes in the global ocean

• Published in: Environmental Microbiology Reports
• Main Authors: Villar, Emilie, Cabrol, Léa, Heimbürger-Boavida, Lars-Eric
• Other Authors: Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU), ANR-15-CE02-0011,IMPEKAB,Impact des changements environnementaux sur les photosymbioses planctoniques(2015)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Antarc*; Antarctic; Sea ice
• Online Access: https://hal.science/hal-02935272; https://hal.science/hal-02935272/document; https://hal.science/hal-02935272/file/648329.full.pdf; https://doi.org/10.1111/1758-2229.12829

International audience Methylmercury is a neurotoxin that bioaccumulates from seawater to high concentrations in marine fish, putting human and ecosystem health at risk. High methylmercury levels have been found in the oxic subsurface waters of all oceans, yet only anaerobic microorganisms have been identified so far as efficient methylmercury producers in anoxic environments. The microaerophilic nitrite oxidizing bacteria Nitrospina has been previously suggested as a possible mercury methylator in Antarctic sea ice. However, the microorganisms processing inorganic mercury into methylmercury in oxic seawater remain unknown. Here we show metagenomic evidence from open ocean for widespread microbial methylmercury production in oxic subsurface waters. We find high abundances of the key mercury methylating genes hgcAB across all oceans corresponding to taxonomic relatives of known mercury methylators from Deltaproteobacteria, Firmicutes and Chloroflexi. Our results