[Spatial and Temporal Characteristics of Community Structure of Nitrite-dependent Anaerobic Methane-oxidizing Bacteria in Paddy Soil]

Paddy fields are one of the most important methane sources, which have great impacts on climate change. The nitrite-dependent anaerobic methane oxidation, by NC10 phylum bacteria- Methylomirabilis oxyfera ()-like bacteria, is a new process regulating methane emission from paddy fields. However, little is known about the spatial and temporal variations of -like bacterial communities and the regulating factors in paddy soils. We investigated the community composition, diversity, and abundance of -like bacteria in 0-40 cm depth of paddy soils at key growth stages of rice, including tillering, jointing, flowering, and milky stages. Results of high-throughput sequencing showed that community composition of -like bacteria differed significantly among different soil layers, while no significant variation was observed among different rice growth stages. The diversity of -like bacteria increased with soil depth. Real-time quantitative PCR showed that the 16S rRNA gene abundance of -like bacteria ranged from 5.73×10 to 2.56×10 copies·g (dry weight), with the highest gene abundance in the 10-20 cm layer. Further, the abundance of these bacteria showed a decreasing trend with rice growth. Soil organic carbon content and soil pH were correlated with the -like bacterial community structures and abundance. In all, our results suggested a certain degree of heterogeneity of spatial and temporal distribution of -like bacterial communities in paddy soils, which was largely influenced by soil organic carbon and soil pH.