Metal bioremediation potential of the halophilic bacterium, Halomonas sp. strain WQL9 isolated from Lake Qarun, Egypt

Abstract

This study is designed to recover and characterize heavy metal resistant halophilic bacteria from Egypt in order to identify mechanisms, plasmids’ role, factors affecting lead (Pb) resistance, and screen for potential industrial and therapeutic enzyme production. Forty-five heavy metal resistant halophilic bacteria were recovered from eleven locations in Lake Qarun, Egypt. The WQL9 isolate showed high Pb resistance up to 4 mM and was resistant to other metals. The 16S rRNA gene analysis and phenotypic characteristics revealed that WQL9 strain belongs to the genus Halomonas. WQL9 growth in Pb-medium supplemented with glucose, yeast, and peptone increased significantly (p < 0.05) at 24 °C and pH 5. During the first 6 h, the lead uptake reached 94%. Transmission electron microscopy clarified that Pb nanoparticles were synthesized within the cell and accumulated on the exopolysaccharide area. The test strain exhibited esterase, lipase, amylase, and L-asparaginase activity. In conclusion, the WQL9 strain is a rapid and excellent tool for Pb bioremediation and a source of useful enzyme production. Keywords: Bioremediation, Halophilic bacteria, Halomonas, Heavy metals, Egypt