基于高通量测序的杨树人工林根际和非根际细菌群落结构比较

Comparison on bacterial community of rhizosphere and bulk soil of poplar plantation based on pyrosequencing

为准确分析定殖在根际和非根际土壤的细菌类群组成,采用454高通量测序技术,对杨树人工林根际和非根际细菌群落进行对比分析.本次测序共获得原始序列70 081条,过滤后序列总数为44 009条.物种注释结果显示,根际土壤包含145个细菌属,非根际土壤包含141个细菌属.根际和非根际相对丰度>4%的属有8个,它们是Acidobacterium GP1、Acidobacterium GP3、Acidobacterium GP6、Gemmatimonas、Bradyrhizobium、Burkholderia、Streptomyces和Acidobacterium GP4,同一属的细菌类群在根际和非根际土壤中相对丰度存在显著差异(P<0.05).α多样性分析表明,根际土壤细菌群落多样性高于非根际土壤,但差异未达到显著水平.细菌群落排序结果较好地反映了土壤细菌群落从根际到非根际的变化和不同取样点的空间差异,根际效应对细菌群落差异的贡献率占21.2%.β多样性分析表明,杨树人工林根际和非根际土壤样品间细菌群落组成具有较大差异,根际和非根际土壤中各含有一些特有属(根际15个,非根际11个),此外还发现丰度发生显著变化的23个属,主要以纤维素降解菌和固氮菌属为主.本研究表明,根系对根际微生物的选择是导致根际微生物群落组成和结构发生显著差异的重要机制,这将对根土界面碳氮循环产生显著影响.

By the 454 pyrosequencing technology,this research compared the bacterial communities in poplar plantation rhizosphere and bulk soil for an accurate understanding of bacterial community colonization in the two soil environments.The species annotation showed that rhizosphere soil contained 145 bacterial genera and bulk soil contained 141 bacterial genera,with 8 common genera shared by both at a relative abundance of more than 4%.The 8 genera in common were Acidobacterium GP1,Acidobacterium GP3,Acidobacterium GP6,Gemmatimonas,Bradyrhizobium,Burkholderia,Streptomyces and Acidobacterium GP4.The relative abundance of the same bacterial community was significantly different between rhizosphere and bulk soil environments.Alpha diversity analysis showed that the bacterial community diversity of rhizosphere soil was higher than that of bulk soil,but the difference was not significant.The results of bacterial communities sorting could reflect the variation of soil bacterial communities from rhizosphere to the bulk and the spatial variation among different sampling points,indicating a contribution of about 21.2%variance of bacterial communities by the effect of rhizosphere.Beta diversity analysis showed great difference between rhizosphere and bulk soil samples in bacterial community composition.There were15 genera specific to rhizosphere soil and 11 to bulk soil.The abundance of 23 genera,mainly cellulose degrading bacteria and nitrogen-fixing bacteria,changed significantly.Selectivity of root to rhizosphere microorganisms is an important mechanism leading to significant differences in the rhizosphere microbial community composition and structure,which may significantly impact the carbon and nitrogen cycles of the root-soil interface.