Biomimetic strategies to design metallic proteins for detoxification of hazardous heavy metal.

Discharge of hazardous heavy metals in to the environment poses a serious threat to the ecosystem owing to its non-degradability and indestructability. Physical and chemical techniques for the removal of heavy metals from industrial effluent is expensive and causes secondary pollution. On the other hand, biological processes using microorganisms play a vital role due to their large surface area to volume ratio, which increases the interactions with metal ions present in the environment. Here, we developed a third generation biological tool for the removal of heavy metal (copper) from the effluent through the biosynthesis of intracellular and surface displayed metallic proteins with novel metal co-ordination chemistry. We evaluated the cell viability for maximum heavy metal adsorption and metal tolerance of synthesized congener metallic proteins. Finally, to eliminate the cost associated with incorporation of metal binding aminoacid, we have introduced a genetic circuit in order to evolve a novel magnetotactic bacterium. The bioreactor studies of the consortia of metallic protein expressing cells immobilized on functionalized granular activated carbon revealed that 97% of copper was adsorbed from the industrial effluent. It is evident that the use of congener metallic proteins will be a futuristic approach for the treatment of wastewater facilitating environmental detoxification.