SELECTION A MULTI-METAL RESISTANT BACTERIA FROM ENVIRONMENTAL SAMPLES FOR BIOREMEDIATION PURPOSES

Background and Aim:Mercury and selenate are among the most toxic elements and can give rise to the irreversibly damage to the CNS and abnormalities. As the various forms of them are stable in environment, many of microorganisms have developed resistance systems and can play role in bioremediation. Thus the aims of this research are isolation and multi-metal resistance capability of bacteria and finally identification of the best bacteria.Methods:At the beginning, isolation of mercury-resistant bacteria in mLB agar medium containg HgCl2 was performed. The best isolates were selected using Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) methods at the range of 25-800ppm HgCl2. Following, selenate resistance capacity of one isolate was evaluated at the range of 32.5-1200mM. Identification of metal resistant isolate are doing.Results:By culturing collected environmental samples on suitable medium, above 50 colonies were isolated. Using predefined tests, an isolate was selected; MIC and MBC of this isolate was 400ppm to mercury and 600mM and 1200mM to selenate, respectively. The primary identification test showed that this isolate was gam negative bacteria belonging to Enterobacteriacae family.Conclusion:Bioremediation can be used to clean unwanted substances from air, soil, water and raw materials from industrial processing. It should be noted that furthur studies such as detection of sorption mechanism and process optimization need to be done. Moreover, it could be noticed that if metal resistant genes of this isolate determine, cloning of them can help for designing biofilters.

Keywords:

Multi-metal resistance , bacteria , biofilter