Inhibition experiments on anaerobic methane oxidation

Area of Science:

• Marine microbial ecology
• Biogeochemical cycles
• Anaerobic respiration

Background:

• Anaerobic methane oxidation (AMO) is vital for regulating methane emissions from marine sediments.
• The specific microorganisms and biochemical pathways responsible for AMO remain largely unidentified.
• Previous research suggested potential roles for sulfate-reducing bacteria and methanogens in methane oxidation.

Purpose of the Study:

• To investigate the microbial mediators of anaerobic methane oxidation in marine sediments.
• To determine if sulfate-reducing bacteria or methanogens are directly responsible for methane oxidation.
• To elucidate the electron acceptors and substrates involved in the AMO process.

Main Methods:

• Incubation of marine sediments from the methane oxidation zone.
• Application of specific inhibitors: molybdate (sulfate reduction), 2-bromoethanesulfonic acid (methanogenesis), and fluoroacetate (acetate utilization).
• Monitoring methane oxidation rates under inhibited conditions.

Main Results:

• Inhibition of sulfate reduction, methanogenesis, or acetate utilization did not significantly halt methane oxidation.
• These findings indicate that neither sulfate-reducing bacteria nor methanogens directly mediate anaerobic methane oxidation in this environment.
• Methane oxidation rates were not directly linked to the activity of these known microbial groups.

Conclusions:

• Anaerobic methane oxidation in the studied marine sediments is not directly mediated by sulfate-reducing bacteria or methanogens.
• The results support the hypothesis that an unknown microorganism or a microbial consortium, possibly involving an unknown methane oxidizer and sulfate-reducing bacteria, is responsible for AMO.
• Further research is needed to isolate the responsible organism(s) and fully understand the AMO pathway.