Chromium-reducing Alcaligenes faecalis and chromium-tolerant Lysinibacillus macroides microbial communities for...

Soil Cr(Ⅵ) pollution is severe environmental threat. This study investigated a targeted microbial consortium system engineered with A. faecalis S1 and L. macroides S2, which exhibits both high chromium tolerance and reduction capabilities. We systematically analyzed its molecular reduction mechanisms under Cr(Ⅵ) stress and its potential synergistic remediation capacity. Results indicate that the microbial consortium HJ group achieved the highest Cr(Ⅵ) removal rate of 81.5 % after 60 days, approximately three times that of CK. Under chromium stress, S1 reduced Cr(Ⅵ) to Cr(Ⅲ) via the quinone reductase electron transport chain and sulfate reductase/sulfite reductase, while simultaneously activating antioxidant systems to scavenge byproduct ROS. Cr(Ⅲ) or chromium-containing complexes were effluxed extracellularly using ABC/MFS transporters. S2 enhances antioxidant stress resistance by upregulating the DNA repair gene pcrA and cytochrome oxidase genes. S1 and S2 demonstrate significant synergistic advantages in remediating Cr(Ⅵ)-contaminated soil, providing both theoretical basis and practical value for their engineered applications.