The duality of metals puts them at the forefront of interest in microbial physiology. Whether metals have an essential biological role or not, at high concentrations they are extremely toxic as well as stable and recalcitrant. Nevertheless, modern technology is increasingly dependent on them. Excessive anthropogenic use generates continuous and increasing exposure to metals and metalloids. As a result, many environments are severely contaminated with metals. Although this creates serious environmental problems worldwide, the increasing demand for metals also drives efforts to meet this demand in a sustainable way as well as to increase the end-of-life recycling rate of them.