Rhizosphere Microbial Activities Enhance Heavy Metal Bioavailability and Plant Uptake.

Heavy metal contamination of soils poses significant hazard to human, plant, and animal health in addition to reducing or eliminating the functional capacity of a given ecosystem.  The concept of phytoextraction of metal-contaminated soils relies on the use of plants to extract and translocate metals to their harvestable parts.  However, in many soil environments, trace metals of interest are often in recalcitrant forms, not readily available for plant uptake and not conducive to phytoextraction.  Soil microbial activity has been identified on numerous occasions as the key factor in metal phytoavailability and in phytoremediation of metal contaminated sites, but specific mechanisms often remain unclear.  In this study, soil microbial sulfur oxidation and siderophore production were explored as potential mechanisms facilitating Zinc and Cadmium bioavailability and subsequent plant uptake in circumneutral metalliferous peat soils.