Effects of novel Cd mobilization bacteria and bone meal on the structure and function of soil bacterial communities and cadmium phytoremediation potential

Abstract

Phytoremediation techniques for heavy metals in soils are inefficient due to phytotoxicity and low bioavailability of heavy metals in soils. Therefore, it is crucial to improve the bioavailability of cadmium (Cd) in soils and plant biomass. In this study, bacteria (L8) with high tolerance to heavy metals were isolated and screened from landfills. Bone meal (BM) was used as an organic amendment to form a synergistic enhancement system with L8 to improve the efficiency of phytoextraction of Cd from soil. A total of four treatments were set up: Control treatment (CK), L8 treatment (T1), 0.5% bone meal treatment (T2), and 0.5% bone meal + L8 treatment (T3). Compared with CK, ryegrass biomass and Cd accumulation in the T3 treatment group increased by 28.36% and 131.81%, respectively. Microbiome and metabolome analyses showed that the combination of bone meal and L8 significantly altered the inter-root microbial community and increased the levels of metabolites associated with the stress response. The combination of bone meal and L8 increased ryegrass biomass and plant detoxification. This was mainly attributed to an increase in the content of amino acids, esters, carbohydrates and sugars in the soil, as well as an increase in antioxidants and soil enzyme activity associated with stress tolerance.The results of this study provide novel insights into efficient remediation of heavy metals in soils, and present a simple and environmentally friendly method to facilitate the mobilization and phytoextraction of Cd from contaminated soils.