Various methods in which synthetic biology can be used to promote the capture of metals as either metal ions (M+) or reduced forms (M).
(A) Absorption by an organism both on the cell surface, and intracellularly. (B) The addition of phytochelatins and metallothioneins for the accumulation of metals either for cell surface display, using a membrane anchor, or intracellularly. This acts not only as a platform for metal ions but for the reduction in metals. (C) Influx and efflux of metal ions leading to intracellular accumulation or detoxification, respectively. (D) The compartmentalisation of metal ions as well as their precipitation into reduced forms in nanocapsules/microcompartments. (E) Membrane bound, or cell-free cytochromes and hydrogenases for the reduction in metal ions to zero-valent forms either inside the cell or at the surface. (F) Glutathione (GSH) for the reduction in metal ions, and the regeneration of GSH from GSSG.