黄土区沟道泥沙微生物群落变化特征及其影响因素

在黄土高原沟壑区，通过16S rRNA基因片段和ITS高通量测序，研究沟道泥沙中细菌和真菌群落在上-中-下游的变化特征.结果表明：与沟头相比，把口站的细菌群落中拟杆菌门（Bacteroidetes）与厚壁菌门（Firmicutes）的相对丰度分别增加6.6%和10.5%，而变形菌门（Proteobacteria）的相对丰度降低15.1%；真菌群落中担子菌门（Basidiomycota）的相对丰度增加7.7%，而子囊菌门（Ascomycota）降低30.2%；泥沙中黏粒含量与细菌丰富度（Chao1指数）和多样性（Shannon指数）之间显著负相关（P<0.05），与真菌的丰富度和多样性无显著相关性；细菌和真菌群落多样性和丰富度的空间差异与SOC、Olsen-P的变化有关（P<0.05）.因此，泥沙中颗粒组成物和养分含量可能是影响沟道微生物群落变化的主要因素.

Variations of soil microbial communities along a valley bottom of the loess plateau and the influencing factors

Sediments were collected from up-to down-stream along a valley bottom on the Loess Plateau. Physicochemical properties of the collected sediments were measured and the characteristics of bacterial and fungal communities in the sediment samples were also determined using the high-throughput sequencing of 16S rRNA gene fragment and ITS. From up-to down-stream of the studied valley, the relative abundance of Bacteroidetes and Firmicutes in the collected sediments increased by 6.6% and 10.5% respectively, and the relative abundance of Proteobacteria decreased by 15.1%. The relative abundance of Basidiomycota increased by 7.7%, while the relative abundance of Ascomycota decreased by 30.2%. The bacterial richness (Chao1index) and diversity (Shannon index) were negatively correlated with sediment clay content (P<0.05), while the correlations between clay content and fungal were not significant. The richness and diversity of bacterial and fungal communities were also correlated with sediment SOC and Olsen-P (P<0.05). Therefore, sediment compositions and nutrient content appeared to be a crucial factor influencing the spatial variability of sediment microbial communities and diversity.