The present invention provides for the removal of mercury utilizing Mer proteins. After the Mer proteins have been expressed and isolated, or alternatively using the native Mer protein complex, either can be used as a chelating agent to remove mercury from any aqueous mercury containing environment. The Mer protein may be used in a solution to bind mercury where the solution contains a Mer proteins may be reversibly attached to a removal apparatus as a Mer ligand. The Mer complex may also be used within a bioreactor to bind and reduce Hg.sup.(2+). The bioreactor may have any competent bacteria capable of producing a Mer complex attached within the bioreactor also containing an inlet and an outlet. In addition, the Mer complex may be enhanced within Mer competent bacteria by a method of enhancement that comprises the creation of a baseline of Mer competent bacterial growth, creating a stock of Mer competent bacteria growing at the baseline level and then adding baseline bacteria to successively higher levels of Hg until the bacteria can grow in 1 mM Hg. The advantage of the Mer proteins is that the mercury binding is exclusive in regards to other metals.