Bioremediation Activity of Pb (II) Resistance Citrobacter sp. MKH2 Isolated from Heavy Metal Contaminated Sites in Iran

Heavy metal pollution all around the world has become a major environmental concern and the bioremediation of polluted environments is an increasingly popular strategy due to both its efficiency and safety. In this study، a bacterial strain resistant to heavy metal was isolated from metal contaminated sites. Strain MKH2 was removed Pb (II) with 95. 06%. This isolate was also resistant to zinc، copper، nickel and cadmium. The results of morphological and physiological characteristics showed that MKH2 was belonging to Citrobacter sp. Moreover، 16S rRNA sequencing and phylogenetic analysis indicated that MKH2 was similar to Citrobacter freundii with 99% homology. Investigation to determine if the gene resistance to heavy metal is located exclusively on a plasmid، curing was achieved. The results suggested that the resistance to heavy metal in the MKH2 is possibly conferred chromosomally. The isolated heavy metal resistant bacterium could be useful for the bioremediation of heavy metal contaminated sites.