Anthraquinone 2-sulfonic acid-mediated reduction of Cr(VI) by Bacillus sp. BT1

Abstract

Bacillus sp. BT1 exhibited enhanced efficiency as well as rate of Cr(VI) reduction in the presence of anthraquinone-2-sulfonic acid (AQS), a quinone compound analogous to humic acid. The culture exhibited 5.67-fold higher Cr(VI) reduction rate in Luria broth containing 100 mg Cr(VI)/L augmented with 1 mM AQS. Furthermore, in the absence of AQS, Bacillus sp. BT1 reduced only 100 mg Cr(VI)/L, whereas in the presence of AQS, it reduced a total of 400 mg Cr(VI)/L, added in form of repeated spikes of 100 mg Cr(VI)/L in each cycle. The activation energy of mediated Cr(VI) reduction was found to be 2.1-fold lower in comparison to nonmediated Cr(VI) reduction. The Cr(VI) and AQS, both induced intracellular quinone and chromate reductases in Bacillus sp. BT1. The results demonstrate the potential of AQS-mediated Cr(VI) reduction by Bacillus sp. BT1 in bioremediation of Cr(VI) containing wastewaters.

Keywords:

• Anthraquinone 2-sulfonic acid
• Redox mediators
• Cr(VI) reduction
• Bacillus

Acknowledgment

Authors are grateful to Department of Science and Technology (DST) and University Grant Commission (UGC), New Delhi, India for providing financial assistance.