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

Cyanobacteria play a relevant role in rice soils due to their contribution to soil fertility through nitrogen (N) fixation and as a promising strategy to mitigate methane (CH) emissions from these systems. However, information is still limited regarding the mechanisms of cyanobacterial modulation of CH cycling in rice soils. Here, we focused on the response of methane cycling microbial communities to inoculation with cyanobacteria in rice soils. We performed a microcosm study comprising rice soil inoculated with either of two cyanobacterial isolates ( sp. and sp.) obtained from a rice paddy. Our results demonstrate that cyanobacterial inoculation reduced CH emissions by 20 times. Yet, the effect on CH cycling microbes differed for the cyanobacterial strains. Type Ia methanotrophs were stimulated by sp. in the surface layer, while sp. had the opposite effect. The overall transcripts of Type Ib methanotrophs were stimulated by . Methanogens were not affected in the surface layer, while their abundance was reduced in the sub surface layer by the presence of sp. Our results indicate that mitigation of methane emission from rice soils based on cyanobacterial inoculants depends on the proper pairing of cyanobacteria-methanotrophs and their respective traits.