Enhancing the effect of novel cd mobilization bacteria on phytoremediation and microecology of cadmium contaminated soil

The efficacy of phytoextraction for remediating heavy-metal contaminated soil depends on the bioavailability of the heavy metals and plant growth. In this study, we employed a synergistic system comprising water-soluble chitosan and the novel Cd mobilization bacteria, <i>Serratia sp</i>. K6 (hereafter K6), to enhance cadmium (Cd) extraction by Lolium perenne L. (ryegrass). The application of chitosan and K6 resulted in an increase in the biomass of ryegrass by 11.81% and Cd accumulation by 73.99% and effective-state Cd by 43.69% and pH decreased by 4.67%, compared to the control group. Microbiome and metabolomics analyses revealed significant alterations in the inter-root microbial ommunity, with rhizobacteria such as <i>Sphingomonas</i>, <i>Nocardioides</i>, and <i>Bacillus</i> likely contributing to enhanced plant growth and Cd accumulation in response to chitosan and K6 addition. Additionally, the contents of various organic acids, amino acids, lipids, and other metabolites exhibited significant changes under different additive treatments, suggesting that ryegrass can regulate its own metabolites to resist Cd stress. This study provides valuable insights into the effects of additives on phytoextraction efficiency and the soil bacterial community, offering a promising approach for phytoremediation of Cd-contaminated soils.