Abstract:

In order to find out the differences in the community structure of prokaryotic microorganisms in different habitats in alpine soils, this study selected four different land use types in the area around Qinghai Lake: pasture, farmland, mountain and grassland, using 16S rRNA Illumina high-throughput sequencing technology and molecular ecological network. To compare the differences in the structure and composition of prokaryotic microbial communities in four different soil habitats, as well as the interactions between prokaryotic species. The results show that the abundance and diversity of prokaryotic microorganisms in the soil vary with different soil habitats. At the bacterial phyla level, Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi and Gemmatimonadetes are dominant in soil bacterial communities in 4 different habitats. Bacteroidetes is the unique dominant phylum in farmland soil, while in mountain and pasture Nitrospirae is the unique dominant phylum. At the archaeal phyla level, Euryarchaeota and Thaumarchaeota are the dominant species in pasture and mountain archaeal communities, and Thaumarchaeota is the only dominant archaea in farmland and pasture soil. Generally, the abundance and diversity of bacteria in the four different habitats are higher than that of archaea. The molecular network structure analysis shows that the number of nodes and connections of the bacterial network is larger, and the system is more complex and more stable than that of archaea. The average path length of the archaeal network is shorter. The average neighborhood connectivity and clustering coefficient of archaea are higher, but the response to the environment is rapid, indicating that the niche of the archaeal community is narrower than that of bacteria. The results of this study revealed that the prokaryotic community is mainly affected by the physical and chemical properties of the soil, and environmental factors such as pH, SOC, TN, AN, AK, C/N and Olsen-P significantly affect the structure of the soil prokaryotic microbial community.

Key words: prokaryotic microorganisms, community structure, molecular ecological network, land-use type, interactions, farming-pastoral ecotone

摘要：

为了探明高寒土壤原核微生物在不同生境中群落结构差异,该研究选择了环青海湖地区牧场、农田、山地和草场4种不同土地利用类型,利用16S rRNA Illumina高通量测序技术和分子生态网络的方法,比较4种不同土壤生境中原核微生物群落结构和组成差异,以及原核生物物种间的相互作用关系。结果表明,不同生境下土壤理化性质存在显著差异,人为干扰会引起土壤矿化,有机养分含量降低,同时影响土壤中速效养分的含量。土壤中原核微生物的丰富度和多样性随着土壤生境的不同而变化,在细菌门水平上,变形菌门（Proteobacteria）、放线菌门（Actinobacteria）、酸杆菌门（Acidobacteria）、绿弯菌门（Chloroflexi）和芽单胞菌门（Gemmatimonadetes）在4种不同生境土壤细菌群落中均占主导地位,拟杆菌门（Bacteroidetes）是农田土壤中的独有优势种,而山地和草场中硝化螺旋菌门（Nitrospirae）为特有优势菌种。在古菌门水平上,广古菌门（Euryarchaeota）和奇古菌门（Thaumarchaeota）是牧场、山地古菌群落中的优势菌种,农田和草场土壤中奇古菌门（Thaumarchaeota）是唯一优势菌种。整体而言,在4种不同生境土壤中细菌群落的丰富度和多样性均高于古菌群落,环境因子中pH、SOC、TN、AN、AK、C/N和Olsen-P显著影响了土壤原核微生物群落结构。分子网络结构分析表明细菌网络的节点数和连接数更多,联系复杂系统更加稳定,古菌网络的平均路径长较小,平均连通度和聚类系数较高,但对环境响应迅速,说明古菌群落的生态位较细菌更加狭窄。

关键词: 原核微生物, 群落结构, 分子生态网络, 土地利用类型, 相互作用, 农牧交错带