Screening and evaluation of Cr(VI) biosorption potential of metal-resistant bacteria isolated from Sukinda chromite mine soil of Odisha

Chromite mine soil is highly contaminated with different heavy metals like chromium, cadmium, lead, and arsenic. In the present study, 42 numbers of metal-tolerant bacteria (Cr-14, Cd-9, Pb-11, and As-8) were isolated from three soil samples collected from chromite mine soils of Sukinda, Odisha using nutrient broth medium supplemented with 50 mg/L of each of the above four metals. The isolated metal-tolerant bacteria were screened using increased above mentioned metal ion concentrations (50, 100 ppm, 200, 500, 700, and 1000 mg/L) to know the maximum resistance of the bacteria towards a particular metal. Out of the 42 predominant bacterial isolates, 4 bacteria (CrS 2 C 7 , PbS 1 M 1 , CdS 2 M 1 and AsS 1 M 2 ) showing high resistance to respective metal ions were subjected to biochemical characterization followed by 16S rRNA sequencing and identified as Pseudomonas argentinensis (CrS 2 C 7 ) , Bacillus subtilis (PbS 1 M 1 ) , Bacillus thuringiensis (CdS 2 M 1 ) , and Bacillus fungorum (AsS 1 M 2 ). Further, the Cr +6 biosorption potential of these 4 bacteria (CrS 2 C 7 , PbS 1 M 1 , AsS 1 M 2 , and CdS 2 M 1 ) were evaluated using 100 mg/L K 2 Cr 2 O 7 metal solution. Out of the above four isolates, P. argentinensis showed highest biosorption of 73.4% for Cr +6 metal ion solution The present finding of Cr +6 biosorption by P. argentinensis indicates that it can be used as an effective biosorbent for biosorption of Cr +6 from chromate contaminated aqueous environment.