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Abstract
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Heavy metal pollution has become one of the biggest environmental problems. Bioremediationof 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 isolatedbacteria, MKH1 had the highest percentage of lead heavy metal removal (99%). Furthermore,this isolate showed high resistance to other heavy metals and cyanide. Examination of themorphological and physiological characteristics of the isolates as well as determination of the16S rRNA gene sequence showed that the MKH1 isolate was similar to Stenotrophomonasmetallophilia with a homology of 99%. Investigation of the mechanism of bioremediation in theisolate showed that functional groups such as carboxyl, amide, carbonyl and hydroxyleffectively remove heavy metals from the growth environment. The results of studying thelocation of the heavy metal resistance gene using the plasmid curing method showed that the leadresistance genes in the MKH1 isolate are located in the plasmid. Bacteria isolated fromcontaminated areas had the ability to remove large amounts of lead. Therefore, these isolatescan be used in industrial wastewater treatment and cleaning of areas contaminated with heavymetals, especially lead.
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