Enzymatic Degradation of Microcystin-LR by Microcystinase (MlrA)

Abstract

Microcystin-LR (MC-LR) is affecting the water supply worldwide. Hence, a way to eliminate this toxin is an essential target. In this study, successful cloning of the mlrA gene and producing MlrA enzyme that can degrade the cyclic MC-LR to linearized MC-LR was done. MlrA protein was expressed in Escherichia coli BL-21 (E. coli). Also, enhancing the MlrA yield by adding nickel to LB media was a success in producing more MlrA enzyme from the same volume. Even though the enzyme showed no activity after adding Ni, the enzyme was expressed at a higher yield. Furthermore, it was to investigate adding methanol to the Sulfonated poly (ether ether ketone) (SPEEK) membrane, which was used for the immobilization of MlrA, to desorb the MC-LR from the membrane when doing the experiment of the immobilized MlrA. Lastly, investigating the enzyme activity before and after enhancing the protein yield and showing that adding the nickel will hinder the MlrA activity while the enzyme that produced in the same conditions without Ni was active.