|Abstract Title:||Unravelling Phototrophic Mercury Transformations by Coupling Laboratory- and Field-Scale Incubation Studies|
|Presenter Name:||JINPING XUE|
|Company/Institution:||Universite de Pau et des Pays de L'Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Matériaux|
|Session:||Special Session - Meta-omic and geochemical approaches to linking microbial activity to biogeochemical mercury cycling|
|Co-Authors:||JINPING XUE,Diva Scuvee,Emmanuel Tessier,Zoyne Pedrero,Marisol Go¤i-Urriza,Remy Guyoneaud,Bahia Khalfaoui Hassani,David Amouroux|
Abstract Information :
Mercury (Hg) has been considered as a global pollutant owing to its volatility and long-range transport. The capability of phototrophic bacteria for Hg reduction and eventually methylmercury (MeHg) methylation/demethylation becomes increasingly apparent in habitats with limited abiotic photochemical transformations of Hg. Systematic studies are still lacking, especially considering the metabolically versatile phototrophs and their complex relationships with other types of microbes (e.g., heterotrophs) in nature. Here we report a coupled research protocol combining laboratory- and field-scale incubation studies to investigate phototrophic Hg transformations (e.g., reduction, methylation and demethylation). Specifically, pre-selected strains of phototrophic bacteria (i.e., Rhodobacter capsulatus and Allochromatium vinosum) were investigated in controlled pure cultures using an experimental setup which can simultaneously and separately examine multiple potential transformation capacities by those phototrophs such as reduction, methylation, and demethylation. In parallel, in-situ incubations were performed on biomats, sediment, and water samples collected in sulfidic hydrothermal springs. In such systems relatively simple but representative microbial consortia comprising of both phototrophs and heterotrophs can be easily examined. The extent of microbial Hg transformations in both types of incubation was obtained using addition of natural or isotopically labelled Hg compounds (i.e., I199Hg, Me201Hg). For pure strain studies, results confirmed the role of Rhodobacter capsulatus (an anoxygenic phototroph) in Hg(II) reduction by examining significant production of Hg(0) relative to experimental controls. For in-situ Hg transformations by microbial consortia from the hydrothermal springs, preliminary results are expected to provide new insights into reduction, methylation, and demethylation processes taking place in such particular environments. Overall, the coupled laboratory- and field-incubation approach is a promising basis for addressing microbial transformations of Hg in natural systems at the molecular, cellular, and community levels.