Enhanced phytoremediation of hexavalent chromium contamination in phosphate mining wasteland by a phosphate solubilizing bacterium

Abstract

Soil chromium (Cr) contamination poses a significant threat to the environment and public health. A phosphate solubilizing bacterial strain Bacillus megaterium PMW-03 was used to enhance the phytoremediation of Cr(VI) contamination by Pteris vittata in phosphate mining wasteland in this study. The results showed that the strain PMW-03 could promote the solubilization of phosphate rock (PR) and the removal of Cr(VI) by Pteris vittata in the phosphate mining wasteland. Compared with the groups not inoculated with PMW-03, the available phosphate content in the rhizosphere soil of the inoculated groups increased by 17.6% and 24.9%, respectively (in the group with Cr(VI) added and the group with Cr(VI) and PR added), and the available Cr(VI) content decreased by 28.2%, 25.2% and 33.4%, respectively. In addition, the strain PMW-03 also promoted the growth of Pteris vittata by secreting indole acetic acid (IAA) and siderophore, promoting Pteris vittata to produce chlorophyll, increasing the concentration of soluble phosphate and reducing the concentration of Cr(VI) in root and shoot. The results of metagenomic analysis showed that changes in biological community structure, enrichment of related functional abundances, and activation of genes (FTH1, FTL, HSP90A, glgP, htpG, glnA, and GLUD1_2) located in microbes contributed to the microbial-phytoremediation of Cr(VI) contamination. These results provide a reference for future research on the microbial-phytoremediation of Cr(VI) contamination in phosphate mining wasteland.