Isolation of chromium resistant bacteria from contaminated soil and its performance evaluation for hexavalent chromium removal

Abstract

The present study deals with the metal tolerance as well as metal resistance characteristic in bacteria isolated from mostly tannery effluent contaminated soil. Seven chromium resistant bacteria (CrRB 1-7) were isolated for this study in LB medium amended with 100 mg/L filter sterilized hexavalent chromium (Cr(VI)) solution. The minimum inhibitory concentrations (MIC) of these gram positive and gram negative bacteria were found in the range of 350 – 450 mg/L of Cr(VI) concentration. Cr(VI) removal potential of these seven isolates were also studied. One isolate CrRB 1 possessed the ability to remove 98.4% Cr(VI) within 24h in LB medium. The effect of hexavalent chromium on their biomass growth potential were further observed. For CrRB1 least differences were found in doubling time calculated from growth curve in presence and absence of Cr(VI). CrRB 1 was then further studied in real life wastewater i.e. tannery effluent to evaluate its performance for removal of Cr(VI).The favorable outcomes encourages for the use of this isolate in green bioremediation technology for tannery industry. The subsequent reactor studies requires to reveal its performance for in-situ application.