Bioremediation of Heavy Metals Using Staphylococcus sp. in Shatt Al-Arab River

Abstract

     Many species are resistant to heavy metals in their surrounding polluted environment and Staphylococcus sp. is an example. This study aimed to isolate and characterize bacteria resistant to heavy metals in the Shatt Al-Arab River in southern Basra, Iraq. Based on the morphology and using Vitek II system, and due to their high resistance to heavy metals (mercury and chromium), two species of Staphylococcus (Staphylococcus lentus and Staphylococcus lugdunensis) were chosen and isolated. The minimum inhibitory concentration (MIC) of the isolates against Hg and Cr was determined after 72 h. of incubation in solid media. All isolates were resistant to Hg (2000 mgL^-1) and Cr (4000mgL^-1). Living biomass of S. lentus and S. lugdunensis was used to remove the heavy metal ions in various concentrations (5, 10 and 25 mgL^-1) of the solutions of aqueous metals. After 72 hours incubation, the removal percentage of S. lugdunensis was 98.91 and 78.78% for Hg and Cr respectively. That for S. lentus it was 77.83% for Cr after 72 hours,  and 98.84% for Hg after 24 h. of incubation. The scanning electron microscope approved that the removal of these metals causes morphological changes in bacteria.