Effects of Acinetobacter johnsonii and Rhodotorula mucilaginosa on the migration and transformation of antimony in soil-pak choi systems

Abstrakt

Soil antimony (Sb) contamination poses serious risks to agricultural product safety and human health. Pak choi, a widely cultivated leafy vegetable, can accumulate Sb in its tissues. Microorganisms can mitigate the bioavailability and toxic effects of heavy metals on crops through various transformation and immobilization mechanisms. In our previous study, two high Sb-resistance strains, Acinetobacter johnsonii and Rhodotorula mucilaginosa, were screened from Sb-containing wastewater. In this study, the remediation effects of these two strains were investigated on Sb-contaminated soil using pak choi pot experiments. The results showed that these two functional microorganisms significantly increased pak choi biomass, root activity, and photosynthetic pigment content through plant growth-promoting traits, such as nitrogen fixation and phosphorus solubilization. More importantly, both strains reduced Sb accumulation in pak choi by promoting the formation of the residual and Fe-Mn oxide-bound Sb and inhibiting the formation of humic acid-bound Sb. Compared with A. johnsonii, R. mucilaginosa exhibited superior performance in promoting pak choi growth and immobilizing Sb. This performance was attributed to the uniquely ability of R. mucilaginosa to restructure the fungal community by enriching beneficial taxa such as Mortierella and Pichia, thereby synergistically enhancing the plant's resilience to Sb stress. This study elucidates the microbial remediation mechanism that influence plant growth and Sb accumulation in Sb-contaminated soil and provides idea for the bioremediation of Sb-contaminated soil.