Rhizosphere soil keystone taxa of Robinia pseudoacacia and Juniperus sabina in an iron tailings matrix and their effects on soil enzyme activity

Background and aimsRhizosphere soil microorganisms play an important role in improving soil nutrients during the phytoremediation of iron tailings. However, little is known about the keystone taxa in rhizosphere soil and their effects on soil enzyme activity.MethodsIn iron mine tailings, rhizosphere soil of 14-year-old Robinia pseudoacacia (R. pseudoacacia) and Juniperus sabina (J. sabina) was selected as the research object. 16S rRNA high-throughput sequencing was performed on rhizosphere soil bacteria of two plants and bare tailings, and soil enzyme activity was determined.ResultsCompared with the bare tailings, the activities of catalase, urease and acid phosphatase in rhizosphere soil of the two plants significantly increased. Compared with the keystone taxa in bare tailings, the keystone taxa number in the other two treatments also increased. The number of keystone taxa in the rhizosphere soil of J. sabina was higher than that R. pseudoacacia and bare tailings. The keystone taxa mainly played an important ecological function in the carbon, nitrogen and phosphorus nutrient cycles, and this function was independent of the relative abundance of these taxa. Compared with bare tailings, the microbial network structures in the rhizosphere soil of the two plants changed, with the number of keystone taxa increasing. In addition, soil catalase, urease and acid phosphatase were significantly correlated with the topological indices and keystone taxa, which played an important role in shaping microbial network topology.ConclusionsCompared with bare tailings, the two plants increased the number of keystone taxa and altered the structure of microbial community network.