Archaea Community And Function Of The Nitrogen Cycle In Surface Sediment From Poyang Lake, China

Archaea is widely distributed in natural environment, even the dominant group, play a critical role in the global biogeochemical process. Ammonia oxidizing bacteria and denitrifying bacteria is the mainly contributer to nitrification and denitrification respectively. In this study, the sediment was collected from 7 sampling sites in Lake Poyang in May 2011. Genomic DNA of the microbial community was extracted from sediment. The microbial community structures were examined by clone libraries and phylogenetic analysis of the 16 s rDNA, aomA gene of ammonium oxidizing bacteria and nosZ gene of denitrifying bacteria. The abundance of the microbial community were examined by quantitive PCR. The result are as follows:The Archaea communities of sediment from Poyang Lake were subjected to the following 3 phyla(Euryarchaeota, Crenarchaeota and Thaumarchaeota), 4 classes, 6 orders, 8 families, 9 genera. The major phyla were Euryarchaeota(48.54%) and Crenarchaeota(39.79%) and the dominant genera were Methanoregula(17.51%), Methanosaeta(14.59%), Methanosarcina(1.86%) and Methanocella(1.08%). Among the sampling sites, the archaea community structure of Xiuhe estuary sites and Fuhe estuary sites were significant difference to other sites. At phylum level, the dominant phyla of Xiuhe site and Fuhe site were Crenarchaeota(68.52% and 76.54% of total) and Euryarchaeota was dominant phylum of Nanzhuhuqu site, Raohe site, Nanjishan site, Xinjiang site and Sanjiangkou site. At genus level, Methanoregula, Methanosaeta and Methanosarcina were the dominant genera of above 5 sites. The TOC, TN, TP, Pb and Cu were the factors which effected the spatial variation of archaea community. The phylogenetic analysis indicated the major biochemical functions of archaea of sediment from Poyang Lake were ammonium and metabolic of methane.The ammonium oxidizing bacteria of sediment from Poyang Lake were all belong to Nitrosomonadaceae, and the dominant genera were Nitrosomonas(43.33%) and Nitrosospira(18.10%). The abundance of ammonium oxidizing bacteria were siginificant difference among sampling sites, Raohe site contained the highest abundance and Xiuhe site was the lowest. The TOC, NH4+, pH, Pb and Cd were the factors which effected the spatial variation of ammonium oxidizing bacteria community. The pearson correlation analysis showed the SM, TP, Cu, Zn and Cd were correlated with the abundance of ammonium oxidizing bacteriaThe denitrifying bacteria in sediment of Poyang Lake were all belong to Proteobacteria. The dominant class were alpha-proteobacteria and beta-proteobacteria, and contained 7 genera: Thiobacillus, Methylotenera, Janthinobacterium, Pseudogulbenkiania, Acidovorax, Rhodobacter and Methylobacterium. The denitrifying bacteria communities were quiet variation among the sampling sites, however the Xiuhe site and Nanjishan site were similar. In addition, the denitrifying bacteria diversity in Sanjiangkou site was the highest and lowest in Raohe site. The abundance of denitrifying bacteria were siginificant difference among sampling sites, Sanjiangkou site contained the highest abundance and Xiuhe site was the lowest. The TOC, TP, Cu and Zn were the factors which effected the spatial variation of denitrifying bacteria community. The pearson correlation analysis showed the TOC was correlated with the abundance of denitrifying bacteria, indicated the nutrients and heavy metal were also the major factors which effect the denitrifying bacteria community in sediment of Poyang Lake.