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The biogeochemical cycle of elements will affect the growth of micro‐organisms. Some metals are essential nutrients for the growth of micro‐organisms (such as Mg, Na, Fe, Co, Cu, Mo, Ni, W, V, and Zn) [2]. Some metal elements can get energy for the metabolism of micro‐organisms through the redox reaction process (such as As(III/V), Fe(II/III), Mn(II/IV), V(IV/V), Se(IV/VI), U(IV/VI)) [3]. There are also some heavy metal ions (such as Ag⁺, Hg²⁺, Cd²⁺, Co²⁺, CrO₄ ²⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺) which possess a great affinity to thiol‐containing groups, and thus can easily replace essential metal ions that are typically present and necessary in many enzymes [4, 5].

The composition of the microflora is governed by their physical and chemical properties [6]. The concentration, chemical speciation, and bioavailability of elements in the soils have obvious effects on microbial growth [7, 8]. At the same time, the production of reactive oxygen species (ROS), including hydrogen peroxide (H₂O₂), superoxide dismutase (O₂ ⁻) and hydroxyl radicals (OH⁻) may alter the intracellular redox status and ultimately cause cell death when the ROS exceeds the antioxidant capacity of the micro‐organism [9]. Low concentration of AuCl₄ ⁻ (<130 μmol/l) could stimulate Rhizopusoryzae to secrete reductive proteins for biological detoxification, but when the concentration of AuCl₄ ⁻ was higher than 130 μmol/l, the ultrastructure of the cells would be destroyed, and growth was significantly inhibited.