Rhodococcus sp. NSX2 modulates the phytoremediation efficiency of a trace metal-contaminated soil by reshaping the rhizosphere microbiome.

Highlights • NSX2 inoculation significantly increased Cd accumulation in S. plumbizincicola. • NSX2 survived in the rhizosphere with a high relative abundance of 1.46%. • NSX2 reshaped the whole bacterial community structure in the rhizosphere. • NSX2 made the rhizosphere bacterial community network more complex. • Enhanced remediation by NSX2 strongly correlated with strengthened network topology. Abstract Hyperaccumulator plants combined with beneficial bacteria is a promising strategy for extracting trace metals from contaminated soils. We explored how the rhizosphere microbiome reshaped by exogenous functional bacteria and whether there is a relationship between the reshaped rhizosphere microbiome and Cadmium (Cd) accumulation in the hyperaccumulator plant during this process. A pot experiment was set up and the Cd hyperaccumulator Sedum plumbizincicola was planted with and without a plant beneficial bacterial strain Rhodococcus sp. NSX2. High-throughput sequencing and random matrix theory (RMT)-based network analysis were used to track the bacterial community in both the rhizosphere and the bulk soil. We found that NSX2 survived in the rhizosphere with a high relative abundance of 1.46% and reshaped the whole bacterial community structure in the rhizosphere. NSX2 inoculation significantly increased Cd accumulation in S. plumbizincicola and the phytoremediation efficiency strongly correlated with the reshaped bacterial network topology. Moreover, NSX2 made the bacterial network in the rhizosphere more complex through cooperating positively with the indigenous bacteria while the network in the bulk soil remained unchanged. We conclude that bacterial inoculation-enhanced phytoremediation did correlate with the beneficial bacterium inoculated itself and also with the subsequently changed indigenous rhizosphere bacterial community and their interactions at the whole community level. [ABSTRACT FROM AUTHOR]