Use of halophilic aquaporin for preparation of biomimetic thin film composite membrane

Abstract

A new aquaporin from a moderate halophile, Halomonas elongata, for fabrication of desalination membrane is introduced in this study. For activity comparison, H. elongata aqp gene and E. coli aqpZ gene were cloned into pGEX-4T-2 vector and expressed in E. coli BL21 cells. E. coli AqpZ (EcAqpZ) appeared as tetrameric form, whereas H. elongata aquaporin (HeAqp) was found mostly as monomers in SDS-PAGE analysis. Light scattering measurements showed that incorporation of aquaporins into the liposomes vesicles resulted in increase in water permeability. HeAqp and EcAqpZ were embedded in 200 nm DOPC liposomes and immobilized with m-phenylene-diamine (MPD) and trimesoyl chloride (TMC) salt rejection layer on polysulfone membrane (PSf). Water with 800 mM NaCl concentration was used for salt rejection experiments. Increasing aquaporin concentration resulted in increase in water permeability of Halomonas aquaporin embedded membranes. % salt rejection of HeAqp and EcAqp incorporated PSf membranes were increased by three fold as compared to control membrane. Salt rejection and water permeability of HeAqp embedded PSf membrane was three and 25 fold higher than that of control membrane, respectively. H. elongata aquaporin, a halophilic aquaporin, was shown to be a suitable candidate for preparation of desalination membranes.