Biochar-immobilized Bacillus megaterium enhances Cd immobilization in soil and promotes Brassica chinensis growth

• Published in: Journal of hazardous materials 2023-09, Vol.458, p.131921-131921, Article 131921
• Main Authors: Qi, Wen-Yu, Chen, Hui, Wang, Zhe, Xing, Su-Fang, Song, Chao, Yan, Zhen, Wang, Shu-Guang
• Format: Article
• Language: English
• Subjects: B-PSB; B. megaterium; Bacillus megaterium; biochar; Bioremediation; Brassica; Brassica rapa subsp. chinensis; cadmium; Cadmium - analysis; Cd contamination; Charcoal; corn straw; food safety; immobilization in soil; microbial communities; Phosphates; phosphorus fertilizers; Soil; soil amendments; Soil inoculant; Soil Pollutants - analysis; solubilization
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.131921

Phosphate solubilizing bacteria (PSB) has been considered an environmental-friendly phosphate fertilizer without cadmium (Cd) input into soils, but its possibility of Cd fixation in soil needs to be explored. Since direct inoculation results in a rapid decline of the population and activity, we immobilized Bacillus megaterium with maize straw biochar (B-PSB) and investigated its feasibility in remediating Cd-contaminated soil. Pot experiments showed that the application of B-PSB significantly ameliorated the growth of Brassica chinensis under Cd stress, with a fresh weight increased by 59.08% compared to the Cd-control. B-PSB reduced Cd accumulation in Brassica chinensis by 61.69%, and promoted the uptake of P and N by 134.97% and 98.71% respectively. Microbial community analysis showed B-PSB recruited more plant growth-promoting bacteria in near-rhizosphere soil, which provides a favorable microenvironment for both PSB and crops. Column leaching experiments verified that B-PSB achieved the dissolution of stable P while fixing Cd. Batch tests further revealed that biochar served as a successful carrier facilitating the growth of B. megaterium and Cd immobilization. Given the widespread Cd contamination in agricultural soils, our results indicate that B-PSB is a promising soil amendment to secure food safety. [Display omitted] •Biochar-immobilized PSB (B-PSB) is employed to remediate Cd-contaminated soil.•B-PSB showed higher capabilities of P solubilization and Cd fixation than PSB alone.•B-PSB alleviated the toxic effects of Cd and improved Brassica chinensis growth.•B-PSB increased the abundances of plant growth-promoting bacteria in soil.