Atmospheric Methane Consumption by Forest Soils and Extracted Bacteria at Different pH Values

Area of Science:

• Environmental Microbiology
• Biogeochemistry
• Soil Science

Background:

• Atmospheric methane (CH4) is a potent greenhouse gas.
• Soil microorganisms play a crucial role in regulating atmospheric CH4 concentrations.
• The influence of soil pH on CH4 consumption by soil bacteria is not fully understood.

Purpose of the Study:

• To investigate the effect of pH on atmospheric methane consumption in forest soils and extracted bacteria.
• To compare the pH response of native soil CH4 consumers with isolated bacterial methanotrophs.
• To explore the potential for distinct physiological groups of methane-oxidizing bacteria in soils.

Main Methods:

• Analysis of CH4 consumption in forest soil slurries across various pH conditions.
• Isolation and characterization of methane-consuming bacteria from soils using high-speed blending and density gradient centrifugation.
• Induction of methanotrophic activity in soils via preincubation with elevated CH4 concentrations.

Main Results:

• Methane consumption was observed in both acidic and alkaline forest soils.
• Isolated bacteria exhibited a distinct pH optimum for methanotrophy (pH 5.8) compared to native soil activity.
• Induced methanotrophs showed pH responses typical of known methanotrophs and were more easily extracted than native consumers.

Conclusions:

• Consumers of ambient methane in soils are physiologically distinct from known methanotrophs, particularly in their pH response.
• The findings suggest the presence of specialized microbial communities responsible for methane oxidation in different soil environments.
• Understanding these distinct microbial groups can inform strategies for methane mitigation and soil microbial ecology research.