Biochar remediates cadmium and lead contaminated soil by stimulating beneficial fungus Aspergillus spp.

Abstract

An in-depth understanding of the micro-ecological mechanisms underlying the remediation of heavy metal-contaminated soils by biochar amendment is crucial for enhancing the efficacy of biochar-microbe combination. Nevertheless, this remediation mechanism remains elusive. Consequently, we performed a pot experiment to investigate the effects of biochar on soil fungal communities in a cadmium (Cd) and lead (Pb) contaminated soil. The results demonstrated that the amendment of biochar derived from rice straw significantly reshaped soil fungal communities, leading to the enrichment of members of the genus Aspergillus, which was found to correlate significantly with the remediation of heavy metal-contaminated soil. A representative of the targeted Aspergillus species (strain F8) was successfully isolated. The results of the pot experiments demonstrated that the inoculation with the isolate F8 can promote plant growth, immobilize soil Cd and Pb, and decrease tomato plant uptake of Cd and Pb. These results indicate that the enrichment of specific taxa induced by biochar amendment is associated with the remediation of heavy metal-contaminated soil. Therefore, this study provides new evidence to support the indirect mechanism of biochar in the remediation of heavy metal-contaminated soil by reshaping the soil microbiome.