Bioreduction and biosorption of Cr(VI) by a novel Bacillus sp. CRB-B1 strain

• Published in: Journal of hazardous materials Vol. 386; p. 121628
• Main Authors: Tan, Hang, Wang, Can, Zeng, Guoquan, Luo, Yao, Li, Hao, Xu, Heng
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.03.2020
• Subjects: Bacillus - metabolism; Biodegradation, Environmental; Bioreduction; Chromium - metabolism; Cr(III) distribution; CRB-B1; Hexavalent chromium; Kinetics; Microcharacterization; Oxidation-Reduction; Soil Microbiology; Soil Pollutants - metabolism; Hexavalent chromium; Bioreduction; Microcharacterization; Cr(III) distribution; CRB-B1
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.121628

[Display omitted] •A novel Bacillus sp. CRB-B1 with the Cr(VI) bioreduction and biosorption capacity was isolated.•Cu2+ enhanced the reduction efficiency of Cr(VI) by Bacillus sp. CRB-B1.•Extracellular reduction was the main site of Bacillus sp. CRB-B1 reduction of Cr(VI).•The reduced Cr was mainly distributed outside the cell. This study reported an efficient novel chromium reducing bacteria (Bacillus sp. CRB-B1) and investigated its removal mechanism. Bacillus sp. CRB-B1 could effectively reduce high level Cr(VI), under a wide range of shaking velocity (125–200 rpm), temperature (33–41 °C), pH (6–9). The co-existing ions Cd2+ and NO3- inhibited its Cr(VI) reduction capacity, while Cu2+ enhanced the reduction efficiency. In addition, Bacillus sp. CRB-B1 could reduce Cr(VI) using glucose and fructose as an electron donor. Micro-characterization analysis confirmed the Cr(VI) reduction and adsorption ability of Bacillus sp. CRB-B1. Cells degeneration result indicated that Cr(VI) removal was mainly bioreduction rather than biosorption. The cell-free suspension had a Cr(VI) removal rate of 68.5.%, which was significantly higher than that of cell-free extracts and cell debris, indicating Cr(VI) reduction mainly occurs extracellularly, and possibly mediated by extracellular reductase. The reduced Cr was mainly distributed in the extracellular suspension, and a small amount was accumulated in the cells. In conclusion, Bacillus sp. CRB-B1 was a highly efficient Cr(VI) reducing bacteria, which has potential in the remediation of Cr(VI)-containing water and soil.