毛乌素沙地不同类型生物结皮细菌群落差异及其驱动因子

Variation of bacterial communities and their driving factors in different types of biological soil crusts in Mu Us sandy land

生物结皮在干旱半干旱区具有极为重要的生态功能,细菌是生物结皮中的重要微生物类群,在生物结皮形成、养分循环与调控过程中发挥着关键作用。然而,对于毛乌素沙地生物结皮演替过程中细菌群落多样性和关键环境因子的认识尚不清楚。因此,本文通过q PCR和高通量测序方法调查了毛乌素沙地裸地、藻结皮、地衣结皮和藓结皮之间的细菌丰度和群落多样性,并探究了生物结皮中细菌群落及其与关键环境因子之间的关系。结果表明,随着生物结皮的演替,细菌16S rRNA基因丰度呈显著上升趋势,细菌Chao1、Shannon指数和系统发育多样性呈先降低后增加的模式。生物结皮不同阶段的细菌门、目和属的相对丰度均存在显著差异,在裸地阶段优势细菌类群是拟杆菌门的噬几丁质菌目、放线菌门的红色杆菌目和变形菌门的根瘤菌目;藻结皮和地衣结皮中均以蓝藻门的颤藻目占绝对优势;藓结皮的细菌以拟杆菌门的噬几丁质菌目和变形菌门的根瘤菌目占优势。全磷、全氮、pH和总有机碳是影响土壤细菌群落的关键环境因子。综上所述,生物结皮的演替通过改变土壤理化特性,为细菌群落提供了不同生态位,其中,土壤养分和pH等环境因子对毛乌素沙地生物结皮细菌物种筛选和群落塑造发挥着重要作用。

Aims:Biological soil crusts(BSCs)have important ecological function in arid and semiarid lands.Bacterial community is key to BSCs by playing critical roles in BSCs formation,nutrient cycles and regulatory process.However,bacterial community diversity in BSCs succession and the key environmental factors in Mu Us sandy land remains unclear.Methods:This study selected bare soil,algal crusts,lichen crusts and moss crusts in Mu Us sandy land as objects.Bacterial abundance and community diversity were investigated by qPCR and Miseq sequencing techniques.The relationship between bacterial community diversity and key environmental factors was explored.Result:The results indicated that 16S rRNA gene abundance significantly increased with BSCs succession.The index of Chao 1,Shannon diversity and phylogenetic diversity of bacterial community decreased from bare soil to algal crusts and then increased from algal crusts to lichen crusts and moss crusts.There were significant differences in the relative abundance of bacterial phylum,order and genus among different BSCs stages.In bare soil,bacterial communities were dominated by Chitinophagales(Bacteroidota),Tubrobacterales(Actonobacteriota)and Rhizobiales(Proteobacteria).Oscillatoriales(Cyanobacteria)was dominant in algal and lichen crusts,and Chitinophagales(Bacteroidota)and Rhizobiales(Proteobacteria)were dominant members in moss crusts.Total phosphorous,total nitrogen,pH and total organic carbon were key environmental factors in shaping soil bacterial communities.Conclusion:BSCs succession provides different niches for bacterial communities by changing soil physicochemical characteristics.Soil nutrients(total phosphorous,total nitrogen and soil total organic carbon)and pH play critical roles in screening bacterial species and shaping bacterial community of BSCs in the Mu Us sandy land.