Integrating biochar, microbe, and hyperaccumulator for sustainable remediation of soils contaminated with heavy metals

The integrated application of biochar, hyperaccumulators, and specific microorganisms offers an effective and environmentally sustainable bioremediation strategy for heavy metal-contaminated soils. However, most current research predominantly focuses on preliminary investigations and pairwise interactions among these components, critical gaps still persist in understanding the complex soil rhizosphere interface reactions and the functional role of extracellular polymeric substances (EPS) in this ternary system. This paper first provides a relatively comprehensive review to the individual remediation effects along with involved mechanisms of biochar (enhanced adsorption/stabilization), hyperaccumulators (phytoextraction), and microbes (biotransformation), and then advances the discussion by elucidating the synergistic interactions within the biochar–hyperaccumulator–microbe ternary framework. Key aspects include the biochemical pathways and regulatory mechanisms governing microbial EPS production, the role of EPS in remediating soil heavy metals, and the dynamic root–microbe interactions at the rhizosphere interface under heavy metal stress. By integrating molecular-scale insights with field-scale applicability, this study provides technical references and theoretical foundations for the future combined application of biochar with microorganisms, hyperaccumulators, and other environmental elements to achieve more efficient and sustainable remediation of metal-contaminated soils.