Characterization of Five Chromium-Removing Bacteria Isolated from Chromium-Contaminated Soil

The potential for bioremediation of chromium pollution using bacteria was investigated in this study. Five chromium-removing bacteria strains were successfully isolated from Cr(VI) contaminated soils and identified by their 16S rRNA gene sequences. The optimum growth temperature (30-40 degrees C) and pH (8.5-11) for the five isolates were investigated. The effect of initial Cr(VI) concentrations (0-1,575 mg L (1)) on bacterial growth was also studied. Results showed that Pseudochrobactrum saccharolyticum strain W1 had high chromium-removing ability and could grow at Cr(VI) concentrations from 0 to 1,225 mg L-1. To our knowledge, this is the first report of chromium removal by a member of the Pseudochrobactrum genus. Sporosarcina saromensis W5 had the highest chromium-removing rate of 0.79 mg h(-1) mg(-1) biomass. Exopolysaccharide (EPS) production and components of the five bacteria strains were also investigated, and a positive relationship was found between the bacterial chromium removal and EPS production.