冻融凹陷对瓦颜山河源湿地土壤微生物群落结构的影响

Effect of Freeze-thaw Depression on Soil Microbial Community Structure in Wayanshan Heyuan Wetland

青藏高原土壤微生物对气候变化敏感度较高,冻融凹陷显著影响土壤微生物多样性及碳氮代谢等过程。以青藏高原瓦颜山河源湿地表层土壤为研究对象,采用宏基因组测序手段,探究冻融凹陷对土壤微生物组成、多样性及代谢通路的影响。结果表明,冻融凹陷对土壤优势菌群的门类无显著性影响,细菌优势门为变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、浮霉菌门(Planctomycetes)、拟杆菌门(Bacteroidetes),真菌优势门为子囊菌门(Ascomycota)。冻融凹陷显著降低了变形菌门的相对丰度,提高了放线菌门和子囊菌门的相对丰度。冻融凹陷显著影响土壤微生物α多样性指数,其Chao1指数、Richness指数显著高于自然对照的,表明冻融凹陷显著提高了土壤微生物的丰富度;Shannon指数显著升高,Simpson指数降低,表明冻融凹陷提高了土壤微生物的多样性。冻融凹陷显著增加了氨基酸代谢、碳代谢等代谢通路的基因数量,减少了双组分系统和群体感应等通路的基因数量。

Soil microorganisms in Qinghai-Tibet Plateau are highly sensitive to climate change,and freeze-thaw depressions significantly affect soil microbial diversity and carbon and nitrogen metabolism.The surface soil of Wayanshan Heyuan wetland in Qinghai-Tibet Plateau was taken as the research object.The method of macro-genome sequencing was used to explore the effects of freeze-thaw on the composition,diversity and metabolic pathway of soil microorganisms.The results showed that the freeze-thaw depression had no significant effect on the dominant bacteria in soil,but the dominant bacteria were Proteobacteria,Actinobacteria,Planctomycetes and Bacteroidetes,and the fungi were Ascomycota.The freeze-thaw depression significantly reduced the relative abundance of Proteobacteria,increased the relative abundance of Actinobacteria and Ascomycota.Freeze-thaw depression significantly affected soil microbialαdiversity,Chao1 index and Richness index were significantly higher than those of natural control,indicating freeze-thaw depression significantly increased the richness of soil microorganisms.The Shannon index was significantly elevated and the Simpson index decreased,indicating freeze-thaw depression improved soil microbial diversity.Freeze-thaw depression significantly increased the gene numbers of amino acid metabolism,carbon metabolism and other metabolic pathways,while decreased those of the two-component system and quorum sensing pathways.