西藏色季拉山不同海拔梯度土壤细菌分布特征

Soil Bacterial Communities Composition at Different Altitudes in Sejila Mountain,Southeastern Xizang

为阐明不同海拔土壤细菌空间分布特征,以西藏东南部色季拉山为研究区,以不同海拔梯度(4606、4110、4000、3900、3440 m)土壤为研究对象,利用高通量测序技术分析0~5 cm和5~10 cm层次土壤细菌多样性特征。结果显示:(1)细菌OTU数、丰富度和多样性均表现出随海拔的下降先下降后升高的“U”型变化趋势;(2)5个海拔共检测到细菌38个门、122个纲、255个目,变形菌门、酸杆菌门、放线菌门、绿弯菌门相对丰度最高,占细菌门总数的10.53%,而相对丰度占89.47%;纲分类水平上,主要优势种群为γ变形菌纲和α变形菌纲,相对丰度分别为41.73%和14.59%;(3)冗余分析结果表明,在细菌门和纲分类水平上,土壤全氮、含水量、有机碳和海拔共分别解释细菌分布的68.44%和67.40%,土壤全氮和含水量是最主要的影响因子;(4)在一级和二级分类水平上分别检测到细菌功能通路7条和40条,其中一级通路中代谢作用功能群占比最高(46.10%~51.86%),代谢作用功能通路中氨基酸代谢和碳水化合物代谢功能群占比最高。结果表明:山体不同海拔高度土壤细菌分布格局可能受采样空间点的连续性及区域土壤、气候因子的综合影响。

In order to elucidate the spatial distribution characteristics of soil bacteria at different altitudes,the Sejila Mountain in southeast Xizang was taken as a model area,the richness of bacterial community composition and relative abundances were analysis by high-throughput sequencing technology along an altitude gradient(4606,4110,4000,3900,3440 m)of 0-5 cm and 5-10 cm layer soil.The results showed that:(1)The number of OTU,bacterial richness and diversity showed a U-shaped variation trend of decreased at first and then increased with the decrease of altitude;(2)The high-throughput sequencing results showed that there were 38 phyla,122 classes,255 orders of bacteria detected at the 5 altitudes areas.Proteobacteria,acidobacteria and actinobacteria had the highest relative abundance,accounting for 10.53%of the total number of phyla and 89.47%of the relative abundance.At the class level,the main dominant populations are gammaproteobacteria and alphaproteobacteria,the relative abundance were 41.73%and 14.59%,respectively;(3)The redundancy analysis found that,soil total nitrogen,water content,organic carbon and altitude accounted for 68.44%and 67.40%of bacterial distribution at the classification level of phylum and class,respectively.The bacterial community was mainly caused by soil total nitrogen and water content.(4)Predicted functions analysis showed 7 classes of primary classification,and 40 bacterial functional pathways of secondary classification.Among which the primary pathway accounted for the highest proportion of metabolic functional groups(46.10-51.86%),and the metabolic functional pathways accounted for the highest proportion of amino acid metabolism and carbohydrate metabolism functional groups,relative abundance were 10.64%and 9.06%,respectively.The results suggested that the distribution pattern of soil bacteria at different altitudes may be affected by the continuity of sampling space points and regional soil and climate factors.