Denitrifying anaerobic methane oxidation and mechanisms influencing it in Yellow River Delta coastal wetland soil, China.

Methane oxidation coupled to denitrification is mediated by Candidatus "Methylomirabilis oxyfera" (M. oxyfera), which belongs to the candidate phylum NC10, and plays a crucial role in the global carbon and nitrogen cycle. Using the Yellow River Delta coastal wetland as the study area, molecular biology technology and laboratory incubation were used to determine the abundance of NC10 bacteria and the denitrifying anaerobic methane oxidation (DAMO) rate in soils from different vegetation areas. The results of the electrophoresis detection show that M. oxyfera-like bacteria can be found in the four types of soils, according to the growth analysis by the system, OTU1 (SA) has been found the highest similarity to first-discovered Candidatus Methylomir-abilis oxyfera (FP565575) (over 98%); Vegetation cover significantly increased the abundance of M. oxyfera-like bacteria compared to beach areas, which abundance was significantly higher in deeper layers than in surface ones. Nitrate, nitrite, total nitrogen, and conductivity were identified as the main environmental factors affecting the DAMO rate. This study showed that both groups A and B of Candidatus M. oxyfera-like bacteria exist in the coastal wetland of the Yellow River Delta, which provides molecular biological evidence for the existence of the DAMO process therein. Moreover, it was revealed the influence mechanism of physical and chemical characteristics of each region on the DAMO rate. This is of significance for furthering our understanding of the coupled effect of the global carbon and nitrogen cycle.