Investigation of the Biosorption mechanism of lead by heavy metal-resistant bacteria

Heavy metal pollution has become one of the biggest environmental problems. Bioremediation of heavy metals by bacteria is a suitable method to reduce these burdens. As part of this study, twelve lead-resistant bacterial were isolated from contaminated areas. Among the isolated bacteria, MKH۱ had the highest percentage of lead heavy metal removal (۹۹%). Furthermore, this isolate showed high resistance to other heavy metals and cyanide. Examination of the morphological and physiological characteristics of the isolates as well as determination of the ۱۶S rRNA gene sequence showed that the MKH۱ isolate was similar to Stenotrophomonas metallophilia with a homology of ۹۹%. Investigation of the mechanism of bioremediation in the isolate showed that functional groups such as carboxyl, amide, carbonyl and hydroxyl effectively remove heavy metals from the growth environment. The results of studying the location of the heavy metal resistance gene using the plasmid curing method showed that the lead resistance genes in the MKH۱ isolate are located in the plasmid. Bacteria isolated from contaminated areas had the ability to remove large amounts of lead. Therefore, these isolates can be used in industrial wastewater treatment and cleaning of areas contaminated with heavy metals, especially lead.

Keywords:

: Bioremediation , Bacteria , Heavy metal , Lead , mechanism.