1 Department of Environmental Engineering, College of Chemistry and Chemical Engineering, Henan University of Science and Technology, Luoyang, Henan, China.
2 Department of Civil and Environmental Engineering, Concordia University, Montreal, Canada.

Chromium, being among the most toxic heavy metals, continues to demand immediate attention in the remediation of Cr-contaminated environments. In this study, a strain of LBA36 (Bacillus toyonensis) was isolated from heavy metal contaminated soil in Luanchuan County, Luoyang City, China. The reduction and adsorption rates of LBA36 in 30 mg·L^-1 Cr-containing medium were 97.95% and 8.8%, respectively. The reduction mechanism was confirmed by Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). Cr(VI) reduction by this strain predominantly occurred outside the cell, with hydroxyl, amide, carboxyl, C-N group, carbonyl, and sulfur carbonyl as the main reaction sites. XPS analysis revealed the presence of Cr_2p1/2 and Cr_2p3/2. Furthermore, the hydroponic experiment showed that the fresh weight and plant height of radish seedlings increased by 87.87% and 37.07%, respectively, after inoculation with LBA36 strain under 7 mg·L^-1 Cr(VI) stress. The levels of chlorophyll, total protein, malondialdehyde, superoxide dismutase and catalase were also affected to different degrees. In conclusion, this study demonstrated the potential of microbial and phytoremediation in the treatment of heavy metal toxicity, and laid the foundation for the development of effective bioremediation methods for Cr(VI) pollution.