ISOLATION AND IDENTIFICATION OF MERCURY RESISTANT BACTERIA FROM THE HENDIJAN S BEACHES AND EVALUATION OF THEIR EFFICIENCY IN BIOREMEDIATION OF MERCURY CONTAMINATED ENVIRONMENTS

Background and Aim:With regards to increasing environmental pollution by heavy metals including mercury, bioremediation using heavy metal resistant bacteria has been paid attention as environmental friendly approach. The purpose of the present study was to isolation and identification of the mercury resistant bacteria from the Hendijan s beaches.Methods:In this study, 3 sampling stations were selected. Isolation and purification of the Hg resistant bacteria were done through cultivation on Hg containing Nutrient Agar medium. The appeared colonies were identified basedon biochemical tests and sequencing of 16S rRNA gene. The growth curve of resistant bacteria was studied at 600 nm and he minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Hg for purified isolates were also investigated. Hg removal rate of the most Hg resistant isolate was also determined through measuring the amount of remained mercury in culture medium.Results:As a result, the selected strain with the most resistance to mercury was identified as Bacillus cereus with 99% similarity to registered sequence in gene bank.The MIC and MBC of Hg for this isolate was 50 ppm and 200ppm, respectively This isolate was able to remove 92% of Hg from culture medium containing 10 ppm mercury.Conclusion:These findings suggest that the isolated bacterium in this study had a good resistance to mercury and can be a suitable option for bioremediation of Hg contaminated wastewaters.

Keywords:

Mercury , Heavy Metals , Bioremediation