“…Despite the fact that many metals, including Cu, Zn, Mn, and Co, are essential for microbial growth at low concentrations, many others have no essential biological function. For instance, As, Cd, Pb, Sn, and Cr are extremely toxic, even at low concentrations 3. All of these ions can exhibit varying degrees of toxicity toward living cells, because they damage molecules through their ability to interact with the thiol groups of proteins, which blocks and inactivates their functions.…”