内蒙古河套灌区不同盐碱程度的土壤细菌群落多样性

摘要

采用变性梯度凝胶电泳(DGGE)技术对内蒙古河套灌区三种不同盐碱程度土壤(盐土,强度盐化土,轻度盐化土)不同深度(0~20cm 和20~30cm)土壤细菌16S rDNA V3～V6可变区扩增片段进行分析,并对土壤理化性质进行了测定.结果表明：细菌群落多样性随土壤盐碱化程度的加深而减少(轻度盐化土>强度盐化土>盐土),随土壤深度的增加而降低(细菌群落多样性0~20cm 土层大于20~30cm 土层).细菌Shannon-Wiener指数在轻度盐化土中最大为3.36,在强度盐化土和盐土分别为3.05和2.49.不同盐碱程度土壤以细菌相似系数聚类,分为0~20cm层与20~30cm层两大族群,土壤细菌群落Shannon-Wiener指数在0~20cm层中(盐土为3.04,强度盐化土为3.29,轻度盐化土为3.36)均大于在20~30cm层(盐土为2.49,强度盐化土为3.05,轻度盐化土为3.14).相关性分析和典范对应分析表明,土壤w(EC)、pH值、w(SOC)、w(TP)是土壤细菌群落结构多样性的显著影响因素,不同盐碱程度土壤中细菌群落的Shannon-Wiener指数与土壤w(EC)(r=-0.542,P<0.05)、pH(r=-0.526,P<0.05)呈显著负相关,与土壤w(SOC)(r=0.700,P<0.01)和w(TP)(r=0.805,P<0.01)呈极显著正相关.w(EC)和pH对盐碱土壤细菌群落结构的影响力最大.回收DGGE图谱中20个优势条带进行测序分析,结果显示,变形菌纲(α-变形菌纲、β-变形菌纲、γ-变形菌纲和δ-变形菌纲)是盐碱土壤的主要类群.%Denaturing gradient gel electrophoresis (DGGE) based on analyzing V3~V6 variable regions of bacterial 16S rDNA, were used to examine the microbial community structure and diversity in different saline-alkaline soils (saline soil, strongly salinized soil and slight salinized soil) and soil depths (0~20cm, 20~30cm)in the Hetao Area of Inner Mongolia. Their physical and chemical properties were measured, respectively. Experimental results showed that bacterial community structure and diversity decreased with the different saline-alkaline soil (slight salinized soil> strongly salinized soil> saline soil)and declined with soil depths (0~20cm>20~30cm). Shannon-Wiener index of bacterial community in slight salinized soil was the highest value (3.36), while it was only 3.05 and 2.49 in strongly salinized soil and saline soil. The cluster analysis of DGGE bands showed that the bacterial community structure and diversity formed two distinct clusters 0~20cm and 20~30cm. Shannon-Wiener index of bacterial community in 0~20cm layer (saline soil 3.04, strongly salinized soil 3.29, slight salinized soil 3.36) were higher than 20~30cm layer (saline soil2.49, strongly salinized soil 3.05, slight salinized soil 3.14). Analyses of Pearson correlation and CCA revealed that variations of bacterial community structure were mainly affected by contents ofw(EC), pH,w(SOC),w(TP). The soil bacteria diversification index has a negative correlation with thew(EC)(r=-0.542,P<0.05)、pH(r=-0.526,P<0.05), and bacterial community diversity exhibited very significant positive correlation withw(SOC)(r=0.700,P<0.01) andw(TP)(r=0.805,P<0.01).w(EC) and pH were the the greatest influence in saline-alkaline soils. Twenty bands were excised from the DGGE gel and re-amplified for 16S rDNA sequencing. Based on the sequencing results, eleven bands can be identified as related to Proteobacteria. These results provide evidence that Proteobacteria are the domain bacterial communities in different saline-alkaline soils of Hetao Area of Inner Mongolia. Saline-alkali soils were mostly bacterial strains belonging to tolerant salty.