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Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water

Methylmercury (MeHg) is a potent neurotoxin commonly found in aquatic environments and primarily formed by microbial methylation of inorganic divalent mercury (Hg(II)) under anoxic conditions. Recent evidence, however, points to the production of MeHg also in oxic pelagic waters, but the magnitude a...

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Autores principales: Rodríguez, Juanjo, Andersson, Agneta, Björn, Erik, Timonen, Sari, Brugel, Sonia, Skrobonja, Aleksandra, Rowe, Owen
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9363918/
https://www.ncbi.nlm.nih.gov/pubmed/35966696
http://dx.doi.org/10.3389/fmicb.2022.809166
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author Rodríguez, Juanjo
Andersson, Agneta
Björn, Erik
Timonen, Sari
Brugel, Sonia
Skrobonja, Aleksandra
Rowe, Owen
author_facet Rodríguez, Juanjo
Andersson, Agneta
Björn, Erik
Timonen, Sari
Brugel, Sonia
Skrobonja, Aleksandra
Rowe, Owen
author_sort Rodríguez, Juanjo
collection PubMed
description Methylmercury (MeHg) is a potent neurotoxin commonly found in aquatic environments and primarily formed by microbial methylation of inorganic divalent mercury (Hg(II)) under anoxic conditions. Recent evidence, however, points to the production of MeHg also in oxic pelagic waters, but the magnitude and the drivers for this process remain unclear. Here, we performed a controlled experiment testing the hypothesis that inputs of terrestrial dissolved organic matter (tDOM) to coastal waters enhance MeHg formation via increased bacterial activity. Natural brackish seawater from a coastal area of the Baltic Sea was exposed to environmentally relevant levels of Hg(II) and additions of tDOM according to climate change scenarios. MeHg formation was observed to be coupled to elevated bacterial production rates, which, in turn, was linked to input levels of tDOM. The increased MeHg formation was, however, not coupled to any specific change in bacterial taxonomic composition nor to an increased abundance of known Hg(II) methylation genes. Instead, we found that the abundance of genes for the overall bacterial carbon metabolism was higher under increased tDOM additions. The findings of this study may have important ecological implications in a changing global climate by pointing to the risk of increased exposure of MeHg to pelagic biota.
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spelling pubmed-93639182022-08-11 Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water Rodríguez, Juanjo Andersson, Agneta Björn, Erik Timonen, Sari Brugel, Sonia Skrobonja, Aleksandra Rowe, Owen Front Microbiol Microbiology Methylmercury (MeHg) is a potent neurotoxin commonly found in aquatic environments and primarily formed by microbial methylation of inorganic divalent mercury (Hg(II)) under anoxic conditions. Recent evidence, however, points to the production of MeHg also in oxic pelagic waters, but the magnitude and the drivers for this process remain unclear. Here, we performed a controlled experiment testing the hypothesis that inputs of terrestrial dissolved organic matter (tDOM) to coastal waters enhance MeHg formation via increased bacterial activity. Natural brackish seawater from a coastal area of the Baltic Sea was exposed to environmentally relevant levels of Hg(II) and additions of tDOM according to climate change scenarios. MeHg formation was observed to be coupled to elevated bacterial production rates, which, in turn, was linked to input levels of tDOM. The increased MeHg formation was, however, not coupled to any specific change in bacterial taxonomic composition nor to an increased abundance of known Hg(II) methylation genes. Instead, we found that the abundance of genes for the overall bacterial carbon metabolism was higher under increased tDOM additions. The findings of this study may have important ecological implications in a changing global climate by pointing to the risk of increased exposure of MeHg to pelagic biota. Frontiers Media S.A. 2022-07-27 /pmc/articles/PMC9363918/ /pubmed/35966696 http://dx.doi.org/10.3389/fmicb.2022.809166 Text en Copyright © 2022 Rodríguez, Andersson, Björn, Timonen, Brugel, Skrobonja and Rowe. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Microbiology
Rodríguez, Juanjo
Andersson, Agneta
Björn, Erik
Timonen, Sari
Brugel, Sonia
Skrobonja, Aleksandra
Rowe, Owen
Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water
title Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water
title_full Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water
title_fullStr Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water
title_full_unstemmed Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water
title_short Inputs of Terrestrial Dissolved Organic Matter Enhance Bacterial Production and Methylmercury Formation in Oxic Coastal Water
title_sort inputs of terrestrial dissolved organic matter enhance bacterial production and methylmercury formation in oxic coastal water
topic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9363918/
https://www.ncbi.nlm.nih.gov/pubmed/35966696
http://dx.doi.org/10.3389/fmicb.2022.809166
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