南极纳尔逊冰川土壤中微生物的群落结构及其代谢特征研究

冰川土壤中的微生物是冰冻圈生态系统中的重要组成部分。南极纳尔逊冰川四周环海，临近海洋的物质输送和其他因素扰动改变了近岸土壤中部分理化因子，从而对土壤中的微生物群落产生影响。本研究采集了南极纳尔逊冰川不同近海距离处的土壤样品，并对其进行了细菌和古菌V4区扩增子测序以及宏基因组测序，探讨了不同近海距离的冰川土壤中的微生物群落结构和代谢潜能。物种多样性结果显示，不同位点的土壤微生物群落组成有所差异，但变形菌门、放线菌门、拟杆菌门等在冰川土壤样品中普遍存在且相对丰度较高。宏基因组分析结果显示，不同近海距离的冰川土壤微生物群落的功能基因分布不同，且能量代谢和跨膜运输等代谢途径的基因的丰度随着采样位点远离海洋而降低。冰川土壤中碳、氮、硫代谢分别以还原性柠檬酸循环、反硝化、同化硫酸盐还原途径为主，其中反硝化途径基因在所有样品中丰度较高。通过分箱组装获得了含有反硝化功能基因的基因组bin＿71,并重构了其核心的代谢通路。本研究初步揭示了南极纳尔逊冰川土壤中微生物的群落结构及代谢潜能，为后续南极冰川土壤新物种的发现、功能基因的挖掘、以及探究全球气候变暖下海洋对沿海生态系统的影响提供了基础数据。

Characterization of microbial community structure and metabolism in soil of Nelson Glacier, Antarctica

Microorganisms in glacial soil are a key component of the cryosphere. Surrounded by the ocean the substance transportations and factors adjacent the Antarctic Nelson Glacier alter or disturb the physicochemical properties of inshore soil, thus affecting the microbial communities in the soil. In this study, soil samples were collected from different distances offshore Nelson Glacier. Then 16S rDNA V4 region amplified sequencing of bacteria and archaea and metagenomic sequencing were performed to investigate the microbial community structure and metabolic potential in glacial soil in different distances from the shore. Results of species diversity analysis showed that the composition of soil microbial communities varied among loci. However, Proteobacteria, Actinobacteria, and Bacteroidetes were commonly present in glacial soil samples with relative high abundance. The results of the metagenomic analysis showed that the distribution of functional genes in microbial communities in glacial soil differed distantly toward the open sea and the gene abundances functioning metabolic pathways such as energy metabolism and transmembrane transport decreased as the sites moved offshore. Carbon, nitrogen, and sulfur metabolism in glacial soil were dominated by the reductive citrate cycle, denitrification and assimilative sulfate reduction pathways, respectively, among which the denitrification pathway genes reached the highest abundance in all samples. The metagenome-assembled genome bin_71 containing the denitrification functional gene was obtained by binning and the core metabolic pathways were reconstructed. This study reveals primarily the community structure and metabolic potential of microorganisms in the soil of Antarctic Nelson glacier, which provides basic data for subsequent discovery of new species and functional genes in the Antarctic glacier soil. Also it explores the impact of the ocean on coastal ecosy stems under global warming.