Fig. 4. Biomineralization is driven by enzymatic activities, and it can process with multi-elements and flow-based systems.

(A) Heatmap of transcriptomic study confirming the up-regulation of genes related to H₂S production and ion efflux pumps. E_1, E_2, and E_3 represent three independent experimental groups, while C_1, C_2, and C_3 are the control groups. The number of the color bar represents fragments per kilobase of exon per million mapped fragments (FPKM). (B) Schematic illustrating how E. coli synthesizes the CdS nanoclusters in the periplasm. (C) Schematic showing that E. coli can use different heavy metals (Mⁿ⁺), including Cd²⁺, Pb²⁺, and Hg²⁺, from flask cultures to form metal sulfides. (D) Plot summarizing individual heavy metal ion removal upon biomineralization. The metal conversion rates of Cd²⁺, Pb²⁺, and Hg²⁺ (0.3 mM each) are 99.28%, 94.72%, and 95.68%, respectively. The cysteine concentration is fixed at 1 mM. The data points represent means ± SD (n = 4). (E) Plot illustrating the simultaneous removal of heavy metal ions upon multiplex biomineralization. The metal conversion rates of Cd²⁺, Pb²⁺, and Hg²⁺ (0.1 mM each) are 98.91%, 98.43%, and 97.10%, respectively. The cysteine concentration is fixed at 1 mM. The data points represent means ± SD (n = 4). (F) STEM image and EDS map showing that E. coli can biosynthesize Cd_xPb_yHg_zS (x + y + z ~ 1), as the locations for different elements are highly correlated in space. Scale bar, 200 nm. (G) Schematic showing a process of forming high-entropy nanoclusters through periplasm-supported biomineralization. (H) Schematic illustrating biomineralization over a replaceable living membrane, composed of E. coli and filter paper, in a continuous bioprocessing reactor. The solid or dashed arrows suggest the flow pattern throughout the bioreactor and its accessories. The green matrix beneath the bacteria is filter. (I) Plot showing the metal conversion of Cd²⁺, Pb²⁺, and Hg²⁺ in the continuous bioprocessing reactor. The semitransparent background shows the actual 3D design of the bioreactor. The data points represent means ± SD (n = 3).