Cabrol Léa, Capo E., Van Vliet D.M., Bastiaan von Meijenfeldt F.A., Bertilsson S., Villanueva L., Sánchez-Andrea I., Björn E., Bravo A.G., Heimburger Boavida L.E. (2023). Redox gradient shapes the abundance and diversity of mercury-methylating microorganisms along the water column of the Black Sea. mSystems, 8 (4), en ligne [18 p.]. ISSN 2379-5077.
Titre du document
Redox gradient shapes the abundance and diversity of mercury-methylating microorganisms along the water column of the Black Sea
Année de publication
2023
Auteurs
Cabrol Léa, Capo E., Van Vliet D.M., Bastiaan von Meijenfeldt F.A., Bertilsson S., Villanueva L., Sánchez-Andrea I., Björn E., Bravo A.G., Heimburger Boavida L.E.
Source
mSystems, 2023,
8 (4), en ligne [18 p.] ISSN 2379-5077
In the global context of seawater deoxygenation triggered by climate change and anthropogenic activities, changes in redox gradients impacting biogeochemical transformations of pollutants, such as mercury, become more likely. Being the largest anoxic basin worldwide, with high concentrations of the potent neurotoxic methylmercury (MeHg), the Black Sea is an ideal natural laboratory to provide new insights about the link between dissolved oxygen concentration and hgcAB gene-carrying (hgc+) microorganisms involved in the formation of MeHg. We combined geochemical and microbial approaches to assess the effect of vertical redox gradients on abundance, diversity, and metabolic potential of hgc+ microorganisms in the Black Sea water column. The abundance of hgcA genes [congruently estimated by quantitative PCR (qPCR) and metagenomics] correlated with MeHg concentration, both maximal in the upper part of the anoxic water. Besides the predominant Desulfobacterales, hgc+ microorganisms belonged to a unique assemblage of diverse previously underappreciated anaerobic fermenters from Anaerolineales, Phycisphaerae (characteristic of the anoxic and sulfidic zone), Kiritimatiellales, and Bacteroidales (characteristic of the suboxic zone). The metabolic versatility of Desulfobacterota differed from strict sulfate reduction in the anoxic water to reduction of various electron acceptors in the suboxic water. Linking microbial activity and contaminant concentration in environmental studies is rare due to the complexity of biological pathways. In this study, we disentangle the role of oxygen in shaping the distribution of Hg-methylating microorganisms consistently with MeHg concentration, and we highlight their taxonomic and metabolic niche partitioning across redox gradients, improving the prediction of the response of marine communities to the expansion of oxygen-deficient zones.
Plan de classement
Climatologie / Météorologie [032CLIMET]
;
Milieux physico-chimique [032MILPHY]
;
Géochimie [064GEOCHI]
Localisation
Fonds IRD [F B010093633]
Identifiant IRD
fdi:010093633
