Dataset Information

Relationship Between Hg Speciation and Hg Methylation/Demethylation Processes in the Sulfate-Reducing Bacterium Pseudodesulfovibrio hydrargyri: Evidences From HERFD-XANES and Nano-XRF.

ABSTRACT: Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation remain poorly understood. Here, we explored the impact of inorganic mercury (IHg) and MeHg concentrations from 0.05 to 50 ?M on the production and degradation of MeHg in two sulfate-reducing bacteria, Pseudodesulfovibrio hydrargyri BerOc1 able to methylate and demethylate mercury and Desulfovibrio desulfuricans G200 only able to demethylate MeHg. MeHg produced by BerOc1 increased with increasing IHg concentration with a maximum attained for 5 ?M, and suggested a saturation of the process. MeHg was mainly found in the supernatant suggesting its export from the cell. Hg L3-edge High- Energy-Resolution-Fluorescence-Detected-X-ray-Absorption-Near-Edge-Structure spectroscopy (HERFD-XANES) identified MeHg produced by BerOc1 as MeHg-cysteine2 form. A dominant tetracoordinated ?HgS form was detected for BerOc1 exposed to the lowest IHg concentrations where methylation was detected. In contrast, at the highest exposure (50 ?M) where Hg methylation was abolished, Hg species drastically changed suggesting a role of Hg speciation in the production of MeHg. The tetracoordinated ?HgS was likely present as nano-particles as suggested by transmission electron microscopy combined to X-ray energy dispersive spectroscopy (TEM-X-EDS) and nano-X ray fluorescence (nano-XRF). When exposed to MeHg, the production of IHg, on the contrary, increased with the increase of MeHg exposure until 50 ?M for both BerOc1 and G200 strains, suggesting that demethylation did not require intact biological activity. The formed IHg species were identified as various tetracoordinated Hg-S forms. These results highlight the important role of thiol ligands and Hg coordination in Hg methylation and demethylation processes.

SUBMITTER: Isaure MP

PROVIDER: S-EPMC7591507 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Publications

Relationship Between Hg Speciation and Hg Methylation/Demethylation Processes in the Sulfate-Reducing Bacterium Pseudodesulfovibrio hydrargyri: Evidences From HERFD-XANES and Nano-XRF.

Isaure Marie-Pierre MP Albertelli Marine M Kieffer Isabelle I Tucoulou Rémi R Petrel Melina M Gontier Etienne E Tessier Emmanuel E Monperrus Mathilde M Goñi-Urriza Marisol M

Frontiers in microbiology 20201014

Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation remain poorly understood. Here, we explored the impact of inorganic mercury (IHg) and MeHg concentrations from 0.05 to 50 μM on the production and degradation of MeHg in two sulfate-reducing bacteria, Pseudodesulfovibrio hydrargyri BerOc1 able to methylate and demethylate mercury and Desulfovibrio desulfuricans G200 o ...[more]

PMID: 33154741

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Project description:Sulfate-reducing bacteria (SRB) colonize the guts of ~50% of humans. We used genome-wide transposon mutagenesis and insertion-site sequencing (INSeq), RNA-Seq, plus mass spectrometry to characterize genetic and environmental factors that impact the niche of Desulfovibrio piger, the most common SRB in a surveyed cohort of healthy USA adults. Gnotobiotic mice were colonized with an assemblage of sequenced human gut bacterial species with or without D. piger and fed diets with different levels and types of carbohydrates and sulfur sources. Diet was a major determinant of functions expressed by this artificial 9-member community and of the genes that impact D. piger fitness; the latter includes high- and low-affinity systems for utilizing ammonia, a limiting resource for D. piger in mice consuming a polysaccharide-rich diet. While genes involved in hydrogen consumption and sulfate reduction are necessary for its colonization, varying dietary free sulfate levels did not significantly alter levels of D. piger, which can obtain sulfate from the host in part via cross-feeding mediated by Bacteroides-encoded sulfatases. Chondroitin sulfate, a common dietary supplement, increased D. piger and H2S levels without compromising gut barrier integrity. A chondroitin sulfate-supplemented diet together with D. piger impacted the assemblage’s substrate utilization preferences, allowing consumption of more reduced carbon sources, and increasing the abundance of the H2-producing Actinobacterium, Collinsella aerofaciens. Our findings provide genetic and metabolic details of how this H2-consuming SRB shapes the responses of a microbiota to diet ingredients, and a framework for examining how individuals lacking D. piger differ from those that harbor it. 8 samples total, 2 gropus of 4 mice: Proximal colon gene expression profiles of gnotobiotic mice colonized with an artificial gut community composed of 8 human gut species (group 1: NoDp) and from mice colonized with the same community plus D. piger (Dp). Mice were fed a HF/HS diet supplemented with 3% chondroitin sulfate. Animals were sacrificed 2 weeks after colonization

Dataset Information

Relationship Between Hg Speciation and Hg Methylation/Demethylation Processes in the Sulfate-Reducing Bacterium Pseudodesulfovibrio hydrargyri: Evidences From HERFD-XANES and Nano-XRF.

Publications

Relationship Between Hg Speciation and Hg Methylation/Demethylation Processes in the Sulfate-Reducing Bacterium <i>Pseudodesulfovibrio hydrargyri</i>: Evidences From HERFD-XANES and Nano-XRF.

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