Characterization of a multimetal resistant Burkholderia fungorum isolated from an e-waste recycling area for its potential in Cd sequestration

The Cd resistance mechanism of a Burkholderia strain isolated from paddy soil of an electronic waste recycling site was characterized for its potential application in metal bioremediation. 16S rRNA gene analysis revealed phylogenetic relatedness of this strain to Burkholderia fungorum. When grown in broth supplemented with Cd, this strain could decrease the bio-available Cd concentration through biosorption of Cd with its capsule or exopolysaccharide. Cd deposition in the cell envelope was confirmed by transmission electron microscopy and energy dispersive X-ray spectroscopy, but no Cd deposition was observed inside the cell. FT-IR revealed a major role of carboxyl, hydroxyl and amino groups along with a possible ion exchange mechanism in cation binding. X-ray powder diffraction analysis showed crystals formed on the exopolysaccharide from the Cd-supplemented culture. Thus our results indicated that sequestration of Cd by exopolysaccharide in the cell envelope might be one potential mechanism for Cd-detoxification in B. fungorum.