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 K. Schaefer, Sylvain Bouchet, Julie Tolu, Erik Björn, Stefan Bertilsson

Research output: Contribution to journalArticle

8 Scopus citations

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
Publication statusPublished - Dec 1 2018

    Fingerprint

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