侵蚀-沉积作用对黄土高原土壤中固碳细菌群落分布特征的影响

The influence of erosion-sedimentation on the distribution characteristics of carbon-fixing bacterial communities in the Loess Plateau

针对黄土高原土壤固碳细菌对侵蚀-沉积的响应规律尚不清晰这一科学问题,在甘肃省罗峪沟流域的主要分支—桥子沟流域选择包括未开垦坡面的侵蚀点和沉积点、刺槐坡面的侵蚀点和沉积点共4个具有代表性的采样点,以土壤样品中有固碳功能基因cbb L的自养细菌为研究对象,采用高通量测序技术研究固碳细菌群落的多样性、分布特征和结构差异。结果显示:刺槐坡面固碳细菌多样性和丰富度明显低于未开垦坡面的。测序数据共鉴定出21个携带cbb L固碳功能基因的自养细菌属,这些属隶属于3个细菌门,包括芽单胞菌门、变形菌门和放线菌门。主坐标分析和聚类分析表明,同一坡面下侵蚀点和沉积点的自养固碳细菌群落构成相似。相关性分析表明,土壤全钾、全氮和pH值与细菌群落组成的变化有很高的相关性。

The response of soil carbon-fixing bacteria to erosion-deposition in the Loess Plateau is still unclear.Therefore,the main branch of the Luoyugou watershed in Gansu Province,Qiaozigou watershed,selected four representative sample sites,including an uncultivated erosional site,an uncultivated depositional site,a Robinia pseudoacacia erosional site and a Robinia pseudoacacia depositional site in this study,taking the autotrophic bacteria with carbon-fixing functional gene cbb L in soil samples as the research object.High-throughput sequencing technology was used to study the diversity,distribution characteristics and structural differences of carbon-fixing bacterial communities.The results showed that the diversity and abundance of carbon-fixing bacteria on R.pseudoacacia slopes were significantly lower than those on uncultivated slopes(P<0.01).Sequencing data identified 21 autotrophic bacterial genera possessing cbb L carbon fixation genes belonging to 3 bacterial phyla,including Blastomonas,Proteobacteria and Actinomycetes.Principal coordinate analysis(PCoA)and cluster analysis showed that the autotrophic carbon-fixing bacterial communities were similar in eroded sites and sedimentary sites under the same slope.Correlation analysis shows that soil total potassium,total nitrogen,and pH have a high correlation with changes in bacterial community composition.