Pedosphere 24(5): 652--661, 2014
ISSN 1002-0160/CN 32-1315/P
©2014 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Aerobic Cr(VI) reduction by an indigenous soil isolate Bacillus thuringiensis BRC-ZYR2 |
HUANG Tian-Pei1, XIAO Ying2, PAN Jie-Ru3, CHEN Zhi1,4, LI Li-Fen1, XU Lei1, ZHANG Ling-Ling1 and GUAN Xiong1 |
1Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002 (China)
2Ningde Entry-Exit Inspection & Quarantine Bureau of P.R.C, Ningde 352100 (China)
3Fuzhou Center for Disease Control and Prevention, Fuzhou 350004 (China)
4State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China) |
| ABSTRACT |
| Chromium (Cr) may cause losses in the yield of field plant, which is one of the favorite habitats of Bacillus thuringiensis (Bt). The purposes of our study were to assess the Cr(VI)-resistance and Cr(VI)-reducing abilities of an indigenous soil isolate of Bt and to determine the factors governing Cr(VI) reduction. Towards this end a novel dichromate-reducing Bt BRC-ZYR2, characterized with insecticidal crystal proteins (ICPs), was isolated from a uranium deposit. Minimum inhibitory concentrations (MICs) of Cr(VI) were determined by broth dilution method and the concentrations of Cr(VI) and total Cr in the supernatant were quantified colorimetrically using 1,5-diphenylcarbazide (DPC) reagent and a mixture of sulfuric-nitric acids, respectively. The isolate contained five ICP genes (cry1Ba, cry1Bb, cry1Be/cry1Bf, cry9Ca and cry9Da) and exhibited a high level of Cr(VI) resistance with MICs of 150 mg L-1 at pH 7.0 and 30 °C, and 500 mg L under optimal conditions (pH 9.0 and 40 °C). The total Cr concentration was similar to initial concentration of Cr(VI) under the optimal condition, suggesting that the essential removal of the Cr(VI) was dependent on Bt reduction. Under optimal conditions, the initial Cr(VI) concentrations from 25 to 75 mg L-1 significantly decreased in 24 h after incubation. Addition of Mn2+, Co2+, Mo2+ and Cu2+ activated Bt-mediated Cr(VI) reduction, while Zn2+, Ni2+ and glucose were found to inhibit the reduction. Our results indicated that this isolate could be a promising biopesticide with the potential for both insect biocontrol and Cr bioremediation in the field. |
| Key Words: bioremediation, uranium deposit, heavy metal, chromium, biopesticide |
| Citation: Huang, T. P., Xiao, Y., Pan, J. R., Chen, Z., Li, L. F., Xu, L., Zhang, L. L. and Guan, X. 2014. Aerobic Cr(VI) reduction by an indigenous soil isolate Bacillus thuringiensis BRC-ZYR2. Pedosphere. 24(5): 652-661. |
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