Accelerating electron transfer reduces CH and CO emissions in paddy soil.

As an accelerated electron transfer device, the influence of microbial electrochemical snorkel (MES) on soil greenhouse gas production remains unclear. Electron transport is the key to methane production and denitrification. We found that the NO amount of the MES treatment was comparable to the control however the cumulative CO and CH emissions were reduced by 50% and 41%, respectively. The content of Fe in MES treatment increased by 31%, which promoted the electron competition of iron reduction to methanogenesis. Furthermore, the competition among iron-reducing, nitrifying and denitrifying bacteria reduced the abundance of methanogens by 19-20%. Additionally, the MES treatment decreased the abundance of genes associated with hydrogen methanogenesis pathway by 6-19%, and inhibited the further conversion of acetyl-CoA into CH for acetoclastic methanogenesis. This study reveals effects of accelerating electron transfer on greenhouse gas emission, and provides a novel strategy for reducing greenhouse gas emissions in paddy soil.