بررسي توانايي باكتري هاي رودخانه كر در حذف بيولوژيكي جيوه

Evaluation of biological removal efficiencies of mercury by the Kor river bacteria

Mercury is one of the most toxic heavy metals. Industrial uses of mercury have led to mercury pollution of the environment. One of the vast strategies to removal of mercury from environment and factories effluent is usage of residing bacteria in mercury contaminated areas . These bacteria can remove mercury using, by reduction process of Hg (II) to Hg (0). The Kor River in the Fars province is highly polluted to mercury due to neighboring to the different industries . In this study the samples were collected from water and sediments of four stations through the Kor River in four seasons (from summer 2006 to spring 2007). Isolation of mercury resistant bacteria was performed using enrichment culture method and directly plating on agar containing mercury. Mercury resistant levels were determined in LB broth containing lO to 90 mg of Hgc12 per liter. Mercury removal efficiencies among the most mercury resistant isolates were calculated by measuring of the remaining mercury in the media. Different bacterial genera such as Pseudomonas sp., E.coli, Bacillus sp. , Serratia marcescens and etc. were identified as mercury resistant bacteria. Some of the isolates were able to tolerate concentrations up to 70 mg of Hgcl2 per liter. Mercury elimination ability of the isolates was different between 28 to 86 percentages. Maximum of mercury elimination efficiency was observed in Pseudomonas sp .3 isolated in spring. This isolate can be ideal for using in biological treatment of mercury from industrial wastewaters.