Persistent activity of aerobic methane-oxidizing bacteria in anoxic lake waters due to metabolic versatility

Sina Schorn (Corresponding author), Jon S Graf, Sten Littmann, Philipp F Hach, Gaute Lavik, Daan R Speth, Carsten J Schubert, Marcel M M Kuypers, Jana Milucka

Publications: Contribution to journalArticlePeer Reviewed

Abstract

Lacustrine methane emissions are strongly mitigated by aerobic methane-oxidizing bacteria (MOB) that are typically most active at the oxic-anoxic interface. Although oxygen is required by the MOB for the first step of methane oxidation, their occurrence in anoxic lake waters has raised the possibility that they are capable of oxidizing methane further anaerobically. Here, we investigate the activity and growth of MOB in Lake Zug, a permanently stratified freshwater lake. The rates of anaerobic methane oxidation in the anoxic hypolimnion reached up to 0.2 µM d-1. Single-cell nanoSIMS measurements, together with metagenomic and metatranscriptomic analyses, linked the measured rates to MOB of the order Methylococcales. Interestingly, their methane assimilation activity was similar under hypoxic and anoxic conditions. Our data suggest that these MOB use fermentation-based methanotrophy as well as denitrification under anoxic conditions, thus offering an explanation for their widespread presence in anoxic habitats such as stratified water columns. Thus, the methane sink capacity of anoxic basins may have been underestimated by not accounting for the anaerobic MOB activity.

Original languageEnglish
Article number5293
Number of pages14
JournalNature Communications
Volume15
Issue number1
DOIs
Publication statusPublished - 21 Jun 2024

Austrian Fields of Science 2012

  • 106026 Ecosystem research
  • 106022 Microbiology

Keywords

  • Methane/metabolism
  • Lakes/microbiology
  • Oxidation-Reduction
  • Anaerobiosis
  • Methylococcaceae/metabolism
  • Metagenomics
  • Oxygen/metabolism

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