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Sand Microbes Produce Methane, Challenging Science
29 Oct
Summary
- Coastal microbes can produce methane despite oxygen exposure.
- Decaying seaweed and seagrass fuel this surprising methane production.
- Scientists isolated microbes with genes protecting against oxygen.
Recent research has revealed that microbes residing in coastal sands can generate methane, a significant greenhouse gas, even when the sediment is frequently exposed to oxygen. This finding challenges the long-held scientific understanding that methane production is primarily confined to environments devoid of oxygen.
The study, published in Nature Geoscience, highlights that methane-producing archaea are the main drivers of this process. These microbes utilize specific chemical compounds released during the decomposition of seaweed and seagrass.
Researchers observed elevated methane levels in coastal waters at Australian and Danish study sites, exceeding atmospheric equilibrium. Laboratory experiments confirmed that methane production rapidly resumes after oxygen exposure and intensifies with the addition of plant material.
Experiments identified methylated compounds, such as trimethylamine, as key fuels for methane production derived from decaying coastal vegetation. These findings suggest that this source of greenhouse gas emissions may have been previously underestimated in marine methane estimates.
Further investigations into microbial resilience demonstrated that repeated oxygen exposure did not halt methane production. Methane output resumed within hours after oxygen removal, and isolated microbial strains showed a rapid recovery and possessed genes offering protection against oxidative stress.
These discoveries have implications for understanding coastal methane emissions, particularly in the context of rising sea temperatures and increased algal growth, which could lead to more frequent blooms and subsequent methane pulses.
