Methanogens and iron-reducing bacteria: The overlooked members of mercury-methylating microbial communities in boreal lakes

Andrea G. Bravo, Sari Peura, Moritz Buck, Omneya Ahmed, Alejandro Mateos-Rivera, Sonia Herrero Ortega, Jeffra Schaefer, Sylvain Bouchet, Julie Tolu, Erik Björn, Stefan Bertilsson

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the hgcA gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems. In the present study, we characterized the diversity of mercury-methylating microbial communities of boreal lake sediments using high-throughput sequencing of 16S rRNA and hgcA genes. Our results show that in the lake sediments, Methanomicrobiales and Geobacteraceae also represent abundant members of the mercury-methylating communities. In fact, incubation experiments with a mercury isotopic tracer and molybdate revealed that only between 38% and 45% of mercury methylation was attributed to sulfate reduction. These results suggest that methanogens and iron-reducing bacteria may contribute to more than half of the mercury methylation in boreal lakes.

Original languageEnglish (US)
Article numbere01774-18
JournalApplied and environmental microbiology
Volume84
Issue number23
DOIs
StatePublished - Dec 1 2018

Fingerprint

iron-reducing bacterium
methanogens
Lakes
Mercury
mercury
microbial communities
microbial community
Iron
iron
Bacteria
lakes
bacteria
lake
methylmercury compounds
methylation
methylmercury
Methylation
Sulfates
lacustrine deposit
Methanomicrobiales

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Keywords

  • 16S rRNA gene
  • Boreal lakes
  • HgcA gene
  • Iron-reducing bacteria
  • Mercury
  • Methanogens
  • Methylation
  • Sulfate-reducing bacteria

Cite this

Bravo, A. G., Peura, S., Buck, M., Ahmed, O., Mateos-Rivera, A., Ortega, S. H., ... Bertilsson, S. (2018). Methanogens and iron-reducing bacteria: The overlooked members of mercury-methylating microbial communities in boreal lakes. Applied and environmental microbiology, 84(23), [e01774-18]. https://doi.org/10.1128/AEM.01774-18
Bravo, Andrea G. ; Peura, Sari ; Buck, Moritz ; Ahmed, Omneya ; Mateos-Rivera, Alejandro ; Ortega, Sonia Herrero ; Schaefer, Jeffra ; Bouchet, Sylvain ; Tolu, Julie ; Björn, Erik ; Bertilsson, Stefan. / Methanogens and iron-reducing bacteria : The overlooked members of mercury-methylating microbial communities in boreal lakes. In: Applied and environmental microbiology. 2018 ; Vol. 84, No. 23.
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abstract = "Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the hgcA gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems. In the present study, we characterized the diversity of mercury-methylating microbial communities of boreal lake sediments using high-throughput sequencing of 16S rRNA and hgcA genes. Our results show that in the lake sediments, Methanomicrobiales and Geobacteraceae also represent abundant members of the mercury-methylating communities. In fact, incubation experiments with a mercury isotopic tracer and molybdate revealed that only between 38{\%} and 45{\%} of mercury methylation was attributed to sulfate reduction. These results suggest that methanogens and iron-reducing bacteria may contribute to more than half of the mercury methylation in boreal lakes.",
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Bravo, AG, Peura, S, Buck, M, Ahmed, O, Mateos-Rivera, A, Ortega, SH, Schaefer, J, Bouchet, S, Tolu, J, Björn, E & Bertilsson, S 2018, 'Methanogens and iron-reducing bacteria: The overlooked members of mercury-methylating microbial communities in boreal lakes', Applied and environmental microbiology, vol. 84, no. 23, e01774-18. https://doi.org/10.1128/AEM.01774-18

Methanogens and iron-reducing bacteria : The overlooked members of mercury-methylating microbial communities in boreal lakes. / Bravo, Andrea G.; Peura, Sari; Buck, Moritz; Ahmed, Omneya; Mateos-Rivera, Alejandro; Ortega, Sonia Herrero; Schaefer, Jeffra; Bouchet, Sylvain; Tolu, Julie; Björn, Erik; Bertilsson, Stefan.

In: Applied and environmental microbiology, Vol. 84, No. 23, e01774-18, 01.12.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Methanogens and iron-reducing bacteria

T2 - The overlooked members of mercury-methylating microbial communities in boreal lakes

AU - Bravo, Andrea G.

AU - Peura, Sari

AU - Buck, Moritz

AU - Ahmed, Omneya

AU - Mateos-Rivera, Alejandro

AU - Ortega, Sonia Herrero

AU - Schaefer, Jeffra

AU - Bouchet, Sylvain

AU - Tolu, Julie

AU - Björn, Erik

AU - Bertilsson, Stefan

PY - 2018/12/1

Y1 - 2018/12/1

N2 - Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the hgcA gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems. In the present study, we characterized the diversity of mercury-methylating microbial communities of boreal lake sediments using high-throughput sequencing of 16S rRNA and hgcA genes. Our results show that in the lake sediments, Methanomicrobiales and Geobacteraceae also represent abundant members of the mercury-methylating communities. In fact, incubation experiments with a mercury isotopic tracer and molybdate revealed that only between 38% and 45% of mercury methylation was attributed to sulfate reduction. These results suggest that methanogens and iron-reducing bacteria may contribute to more than half of the mercury methylation in boreal lakes.

AB - Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the hgcA gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems. In the present study, we characterized the diversity of mercury-methylating microbial communities of boreal lake sediments using high-throughput sequencing of 16S rRNA and hgcA genes. Our results show that in the lake sediments, Methanomicrobiales and Geobacteraceae also represent abundant members of the mercury-methylating communities. In fact, incubation experiments with a mercury isotopic tracer and molybdate revealed that only between 38% and 45% of mercury methylation was attributed to sulfate reduction. These results suggest that methanogens and iron-reducing bacteria may contribute to more than half of the mercury methylation in boreal lakes.

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KW - HgcA gene

KW - Iron-reducing bacteria

KW - Mercury

KW - Methanogens

KW - Methylation

KW - Sulfate-reducing bacteria

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