The key role of Geobacter in regulating emissions and biogeochemical cycling of soil-derived greenhouse gases.

In the past two decades, more and more attentions have been paid to soil-derived greenhouse gases (GHGs) including carbon dioxide (CO), methane (CH) and nitrous oxide (NO) because there are signs that they have rising negative impacts on the sustainability of the earth surface system. Farmlands, particularly paddy soils, have been regarded as the most important emitter of GHGs (nearly 17%) due to a large influx of fertilization and the abundance in animals, plants and microorganisms. Geobacter, as an electroactive microorganism widely occurred in soil, has been well studied on electron transport mechanisms and the direct interspecies electron transfer. These studies on Geobacter illustrate that it has the ability to be involved in the pathways of soil GHG emissions through redox reactions under anaerobic conditions. In this review, production mechanisms of soil-derived GHGs and the amount of these GHGs produced had been first summarized. The cycling process of CH and NO was described from the view of microorganisms and discussed the co-culture relationships between Geobacter and other microorganisms. Furthermore, the role of Geobacter in the production of soil-derived GHGs is defined by biogeochemical cycling. The complete view on the effect of Geobacter on the emission of soil-derived GHGs has been shed light on, and appeals further investigation.