[Community Characteristics of Methanogens and Methanogenic Pathways in Salt-tolerant Rice Soil].

It is known that methanogens play a critical role in the carbon cycle in soil, while methanogen community characteristics and their environmental influencing factors in the soil planted with salt-tolerant rice remain unclear. In this study, methanogen abundance, community composition, and relationships with environmental factors in soils planted with the salt-tolerant rice (YC1703) and ordinary rice (Lindao 10) were evaluated in the rice improvement demonstration base of Qingdao Wisdom Agricultural Industry using real-time fluorescence quantitative PCR and Illumina high-throughput sequencing. The results indicated that the abundance and community richness of methanogens in Lindao 10 soil were significantly higher than those in YC1703 soil, and methanogens in YC1703 soil exhibited higher diversity. The combined effects of rice varieties, rice growth period, and environmental factors had impacts on the methanogen community. The hydrogenotrophic methanogens were dominant in the YC1703 and Lindao 10 soils; thus, we speculated that the dominant pathway of methane production in these soils was hydrogenotrophic methanogenesis.

Environmental DNA Sequencing Reveals a Highly Complex Eukaryote Community in Sansha Yongle Blue Hole, Xisha, South China Sea.

We report an Illumina high-throughput sequencing protocol of eukaryotic microbes in the world's deepest marine blue hole, Sansha Yongle Blue Hole, Xisha, South China Sea. The variable V9 region of small subunit (SSU) rDNA, was sequenced using this approach from the waters of blue hole and outer reef slope. 917,771 unique eukaryotic 18S rRNA gene sequences and 6093 operational taxonomic units (OTUs) were identified. Significant differences in the eukaryotic composition were observed between the blue hole and outer reef slope, and the richness in the blue hole was much higher than that in the outer reef slope. The richness and diversity of eukaryotes in the blue hole were both lowest at 60 m and highest at 100 m depth. Eukaryotic microalgae assemblages dominated by Dinophyceae were the most abundant in the 10-20 m water column in the hole. Fauna was the main group at and below a depth of 60 m, where Araneae and Cyclopoida were dominant in the 60 m and 80 m water layer, respectively. There was a large number of Entoprocta at a depth of 180 m in the hole, where little oxygen was detected. Turbidity and nitrite concentration had a significant effect on the eukaryote community structure (p < 0.01).