Spatial Distribution Characteristics Of Denitrifying Anaerobic Methane Oxidizing Dacteria In Xilin River Wetland

Microorganisms which drive denitrifying anaerobic methane oxidation?Nitrite-Dependent Anaerobic Methane Oxidation,N-DAMO?coupling carbon with nitrogen cycles,play an important role in alleviating greenhouse gas emissions globally.Xilin river wetland in Inner Mongolia plateau is an important ecological barrier for the development of animal husbandry,but also a main source of greenhouse gases.However,there were few reports about N-DAMO bacteria of Xilin river wetland in different landforms and special site polluted by livestock feces.This study selected different landforms,site XRW-RC showing the river bed center of Xilin river wetland,while site XRW-RS showing the edge of the riverbed,site XRW-LF for the low river floodplain,site XRW-HF for high river floodplain,and the site XRW-MA representing the polluted water area caused by livestock manure and urine.Cloned sequencing,real-time fluorescence quantitative PCR technologies and bioinformatics were used to study phylogenetic tree of N-DAMO bacteria,community compositions,abundances,diversity and associated spatial distribution characteristics based on 16S rRNA and pmo A genes.The results of the study were as follows:?1?255 effective sequences of N-DAMO bacterial 16S rRNA gene were obtained from 5 samples and were divided into 35 OTUs on 3%level.Whose similarities with the known Candidatus Methylomirabilis oxyfera ranged from 83%to98%,indicating that N-DAMO bacteria existed in different landforms of Xilin river wetland.?2?83 effective sequences of N-DAMO bacterial pmoA gene were obtained from 3 samples?XRW-RS,XRW-MA,XRW-LF?and were divided into 8 OTUs on2%level.Whose similarities with the known Candidatus Methylomirabilis oxyfera ranged from 83%to 98%,further indicating that N-DAMO bacteria existed in Xilin river wetland.?3?Redundancy analysis?RDA?showed that NO₃^--N and pH were the most important environmental factors affecting N-DAMO bacterial community structure and diversity.?4?Result of real time fluorescence quantitative PCR showed that the abundances of N-DAMO bacterial 16S rRNA gene ranged 8.92�10⁶ to 4.61�10⁷.And the highest abundance existed in XRW-MA area polluted by livestock while the lowest abundance occurred in site XRW-HF from high river floodplain.Pearson correlation analysis showed that the abundances of N-DAMO bacterial 16S rRNA gene were positively correlated with NO₃^--N?p<0.01?,and a positive correlation with water content WC?p<0.05?,while a significantly negative correlation with pH?p<0.05?.Meanwhile there was no significant correlation between the abundances of N-DAMO bacterial 16S rRNA gene and TN,TP,TOC,NH₄⁺-N?p>0.05?.