Phylogeny and comparative modeling of phytochelatin synthase from Chlorella sp. as an efficient bioagent for detoxification of heavy metals

Abstract

Phytochelatins (PCs) found extensively in algae and plants are important for detoxification of heavy metals from soil and wastewater, and their synthesis is mediated by an enzyme phytochelatin synthase (PCS). In this study, a phylogram was generated to study evolutionary relationships of PCS from various organisms. It was revealed that PCS from green algae and plants are orthologs as both have evolved from a common ancestor. PCS from cyanobacteria appeared in two different clades showing that they have followed different lineages during evolution. Structural modeling was also carried out by building a 3D model of PCS from Chlorella variabilis using software Modeller v9.16. The predicted structure will be helpful for protein engineering strategies and to understand its interactions with other proteins. The biological biosorption capacity of Chlorella vulgaris (a green alga) was determined to remove Cd, Cu and Pb from industrial effluents. The biosorption of three heavy metals from industrial waste water was investigated under various conditions like pH, biomass concentration, contact time and temperature. Bio-removal of heavy metals was carried out by exposing culture of C. vulgaris to water samples of different heavy metal concentrations. The decrease in Cd, Cu and Pb quantities after 1 to 7 days of incubation period were 83%, 84% and 82.5%, respectively. In view of this, Chlorella spp. could be used on a large scale to detoxify heavy metals and clean up contaminated environments.