Harnessing the bio-mineralization ability of urease producing Serratia marcescens and Enterobacter cloacae EMB19 for remediation of heavy metal cadmium (Ⅱ)

摘要

In the present study, urease positiveSerratia marcescens(NCIM2919) andEnterobacter cloacaeEMB19 (MTCC10649) were individually evaluated for remediation of cadmium (II) using ureolysis-induced calcium carbonate precipitation. Both the cultures were observed to efficiently remove cadmium from the media through co-precipitation of Cd (II) and Ca (II).S. marcescensandE. cloacaeEMB19, respectively showed 96 and 98% removal of initial 5.0 mg L−1soluble Cd (II) from the urea and CaCl2laden media at 96 h of incubation period. At higher Cd (II) concentrations of 10 and 15 mg L−1, cadmium removal efficiency was much higher in case ofE. cloacaeEMB19 compared toS. marcescens.In-vitrocadmium (II) remediation study using urease containing cell-free culture supernatant ofS. marcescensandE. cloacaeEMB19 showed respective 98 and 53% removal of initial 50 mg L−1 Cd (II) from the reaction mixtures in co-presence of Ca (II). While in sole presence of Cd (II), only 16 and 8% removal of Cd (II) were detected forS. marcescensandE. cloacaeEMB19, respectively. The elemental analysis of the co-precipitated mineral products using Energy Dispersive X-ray spectroscopy (EDX) clearly showed the prevalence of Ca and Cd ions. The morphology Cd-Ca composites formed with respect to both the cultures were observed to be of different shape and size as revealed through Scanning Electron Microscopy (SEM). Entire study hence comes out with a sustainable bioremediation option which could be effectively used to tackle Cd (II) or other heavy metal pollution.