Interactions between Cyanobacteria and Methane Processing Microbes Mitigate Methane Emissions from Rice Soils.

Area of Science:

• Agricultural Microbiology
• Environmental Science
• Soil Science

Background:

• Cyanobacteria enhance rice soil fertility via nitrogen fixation.
• Cyanobacteria offer a potential strategy for mitigating methane emissions in rice systems.
• Mechanisms of cyanobacterial modulation of methane cycling in rice soils require further investigation.

Purpose of the Study:

• To investigate the impact of cyanobacterial inoculation on methane cycling microbial communities in rice soils.
• To compare the effects of two specific cyanobacterial isolates (Calothrix sp. and Nostoc sp.) on methane emission and microbial response.
• To elucidate the role of cyanobacteria in regulating methane production and consumption in paddy fields.

Main Methods:

• Microcosm study using rice soil.
• Inoculation with two distinct cyanobacterial isolates (Calothrix sp. and Nostoc sp.).
• Analysis of methane cycling microbial communities and methane emissions.

Main Results:

• Cyanobacterial inoculation reduced methane emissions by 20-fold.
• Calothrix sp. stimulated Type Ia methanotrophs in the surface layer; Nostoc sp. had an inhibitory effect.
• Nostoc sp. stimulated Type Ib methanotrophs and reduced methanogen abundance in the subsurface layer.

Conclusions:

• Cyanobacterial inoculation is effective in reducing methane emissions from rice soils.
• The impact on methane cycling microbes varies significantly between cyanobacterial strains.
• Effective methane emission mitigation requires strategic pairing of specific cyanobacteria with complementary methanotroph and methanogen traits.