基于高通量测序的巨菌草根系固氮菌群组成及其促生性能分析

High-throughput sequencing-based analysis of composition and growth-promoting effect of root-associated nitrogen-fixing bacteria in Pennisetum giganteum

以巨菌草根表、根表土壤和根围土壤为材料,采用高通量测序技术分析了各样本的固氮菌群组成,并测定其中主要固氮菌株的促生性能.结果表明,巨菌草根系存在丰富的固氮菌群,蓝藻菌门(Cyanobacteria)和变形菌门(Proteobacteria)为主要门类,慢生根瘤菌属(Bradyrhizobium)、芽孢杆菌属(Bacillus)、科萨克氏菌属(Kosakonia)为核心属.从巨菌草根表、根表土壤和根围土壤中分别分离到4.5×10^(5)、4.0×10^(4)和5.4×10^(3)CFU·g^(-1)的固氮菌,经SDS-PAGE全细胞蛋白电泳聚类分析将其分为7个类群;从中筛选得到2株具有良好促生性能的代表菌株,经16S rDNA鉴定分别将其确定为科萨克氏菌(Kosakonia radicincitans)和枯草芽孢杆菌(Bacillus subtilis).与对照组相比,所筛选的2株菌对水培玉米幼苗株高、根长、分根数及盆栽玉米幼苗株高均具有良好的促生作用.

Composition and growth-promoting effect of nitrogen-fixing bacteria isolated from the root surface, surface soil and rhizosphere soil of Pennisetum giganteum were analyzed by high-throughput sequencing technology. The results revealed that abundant nitrogen-fixing bacteria existed in the root system of P.giganteum, amounting to 4.5×10^(5), 4.0×10^(4) and 5.4×10^(3) CFU·g^(-1)in the root surface, root surface soil and rhizosphere soil, respectively. Among them Cyanobacteria and Proteobacteria were the main phyla, and Bradyrhizobium, Bacillus and Kosakonia made up the core genera. The nitrogen-fixing bacteria were divided into 7 groups based on cluster analysis of whole cell protein via SDS-PAGE electropherogram. Two representative strains with good growth-promoting effect were further screened and identified as Kosakonia radicincincians and Bacillus subtilis by 16 S rDNA sequencing analysis. The 2 strains promoted the growth of hydroponic maize seedlings on plant height, root length and differentiated root number, and plant height of potted maize seedlings compared with the control.