Shifts in Rhizosphere Bacterial Community Structure, Co-occurrence Network, and Function of Miscanthus Following Cadmium Exposure

As a representative of second-generation bioenergy plants, Miscanthus has received increasing attention in the studies of heavy metal (HM)-contaminated soil remediation. Currently, few studies have examined the effects of using Miscanthus to remediate HM-contaminated soils on the composition and function of microbial communities. In this study, the Miscanthus cultivar M. saccariflorus was examined for its tolerance and enrichment abilities when grown in soils containing 100 mg•kg-1 of cadmium (Cd). The structure, function, and co-occurrence network of their rhizosphere bacterial communities were analyzed during the remediation process. MiSeq sequencing showed that the Miscanthus rhizosphere bacterial community comprised 32 phyla and 425 genera, including plant growth-promoting rhizobacteria (PGPR), such as Sphingomonas, Bacillus, Gemmatimonas, and Streptomyces. The addition of Cd affected the Miscanthus rhizosphere bacterial community and reduced community diversity. Phylogenetic molecular ecological networks indicated that Cd addition reduced the interactions between Miscanthus rhizosphere bacteria to generate a simpler network structure, increased the number of negative-correlation links, enhanced the competition between rhizosphere bacterial species, and changed the composition of key bacteria. PICRUSt functional predictive analysis indicated that Cd stress reduced soil bacterial functions in the Miscanthus rhizosphere. The results of this study provide a reference for the subsequent regulation of efficient Miscanthus remediation by PGPRs or key bacteria. © 2021, Science Press. All right reserved.