Diversity And Distribution Of Archaea Communities In The Vertical Of Two Permafrost Profiles In The Muli Hydrate Drilling Area Of Qilian Mountain

Permafrost is a huge carbon pool that has an important impact on global climate change.With the constant warming of the global climate and the melting of frozen soil,the organic carbon in the frozen soil is decomposed by microorganisms to produce greenhouse gases such as CO₂ and CH₄.The massive release of these gases will once again exacerbate the greenhouse effect,making the frozen soil layer shift from carbon sink to carbon source.Therefore,to study the ecological diversity,structure,and composition of frozen soil microorganisms,is very important for us understanding their ecological effects with the global warming,and the potential feedbacks to regulate the climate change caused by the microbial decomposition of organic carbon.In this study,the physicochemical properties and the archaeal community structure and composition from two vertical profiles of frozen soils were studied in the hydrated drilling area at Qilian Mountain in China.The results show that the soil methane content in the vertical profile was increasing from the top active layer at 4?l/L to the permafrost layer at 5300?l/L.The total organic carbon content?TOC?in the vertical profile soil was ranging from 2.18%to 18.2%.The archaeal community is mainly composed of Euryarchaeota and Crenarchaeota.Euryarchaeota includes Methanomicrobiales,Methanosarcinales,Methanosaetaceae,Methanobacteriales,Rice cluster V and Thermoplasmata,while Crenarchaeota contains Group1.3b/MCG-A,Group 1.1b and Thermoproteales.Distribution of those groups show that Crenarchaeota was the dominant group in the active layer soils?DP-14:63%⁸6%,DTP-15:56%?;whereas the Euryarchaeota was dominant group in the permafrost soils?DP-14:81%⁸6%,DTP-15:62%?.Taking together,the archaeal community composition is different between the active layer and the permafrost layer,and the permafrost layers present higher rich diversity than that of in the active layers.In addition,two pairs of primers were used in high-throughput sequencing to compare detection of archaeal community.The result show that higher diversity of archaeal community was detected using primers of Arch340F/Arch806R than Arch751/Arch1024R.The archaeal community composition was also different using two pairs of primers,and the set of primer Arch751/Arch1024R tend to detect the important group Methanosarcinales in the permafrost layers,but the other set of primer was not.Two methods,16S rRNA gene library and high-throughput sequencing,are compared for the archaeal community analysis,the result show that a higher diversity of archaeal community was obtained using the high-throughput sequencing method than the method of 16S rRNA gene library.