Production Optimization and Application of Extracellular Chromate Reductase from Bacillus sp. for Bioremediation of Hexavalent Chromium

Abstract

Chromate reductase activity of a highly resistance Bacillus sp. isolated from chromite mine soil of Odisha (India) was associated mainly with the contribution of extracellular enzymes production. The maximum chromate reductase production from Bacillus sp. was achieved in the presence of 50 μM of Cr(VI); 0.5%, (w/v) of glucose;1%, (w/v) of trypton; 0.5%, (w/v) of Na₂HPO₄; 0.5%, (w/v) KNO₃; 0.5%, (w/v) KCl and 0.5%, (w/v) thiamine as source of vitamin with the initial medium pH of 7.0 and incubation at 35 °C under shaking condition (100 rpm) as optimum condition. In these conditions, the chromate reductase production was enhanced to a significant level of 3.67 ± 0.014 U ml⁻¹ as compared to unoptimized condition (2.37 ± 0.029 U ml⁻¹) with decrease in time from 24 h (late log phase) under unoptimized condition to 16 h under optimized condition. The efficacy of purified protein was checked for detoxification of Cr(VI). It was able to detoxify 63% of chromate within a time period of 30 min. Thus, the enhanced production and efficacy of extracellular enzyme by the Bacillus sp. is a promising result which has great potential for its application in bioremediation of hexavalent chromium from environment.