树线变动会对生物多样性分布以及生态系统功能的维持造成深远影响,研究树线处土壤微生物群落及其功能,对预测高海拔生态系统响应气候变化具有重要价值.采用MiSeq高通量测序技术及PICRUSt基因预测分析方法,对北京东灵山辽东栎林及树线之上亚高山草甸的土壤细菌群落及功能进行对比研究,结果表明:土壤细菌物种多样性在树线处没有发生显著的变化,沿海拔也没有呈现出明显趋势,但细菌群落结构以及预测功能基因均发生了变化.在39个二级预测功能分类中有10个子功能的相对多度在森林和草甸中具有明显差异.其中,其他次生产物代谢的生物合成、转录、多糖生物合成和代谢、酶家族、信号分子及交互作用、环境适应、细胞生长和死亡等的功能基因在森林中明显高于草甸中;而维他命及辅因子代谢、膜运输、内分泌系统等的功能基因在草甸中偏高.%Treeline shifts are likely to have a profound impact on the distribution of biodiversity and the maintenance of ecosystem functioning.Understanding the community structure and functioning of soil microorganisms around the treeline is crucial for predicting the response of ecosystems to global climate change.In this study,we investigated the soil bacterial communities and their function in a Quercus liaotungensis forest and the meadow above the treeline at Mount Dongling,using 16S rRNA gene sequencing and PICRUSt analysis.The results showed that soil bacterial species richness did not significantly change at the treeline,and there was no obvious trend along the elevation gradient.However,the bacterial community structure and the predicted functional profiles changed at the treeline.Within the 39 predicted functional categories at KEGG pathway hierarchy level 2,11 categories showed apparent differences between forest and meadow.Relative abundance of gene families related to biosynthesis of other secondary metabolites,transcription,glycan biosynthesis and metabolism,enzyme families,signaling molecules and interaction,environmental adaptation,growth,and death tended to be higher in the forest,whereas the abundance of gene families related to metabolism of cofactors and vitamins,membrane transport,and the endocrine system were significantly higher in the meadow.In future studies of microbial ecology,more attention should be paid to community composition and functioning instead of species diversity.
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