1. Simultaneous mitigation of tissue cadmium and lead accumulation in rice via sulfate-reducing bacterium.
- Author
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Shan, Shiping, Guo, Zhaohui, Lei, Ping, Wang, Yushuang, Li, Yilu, Cheng, Wei, Zhang, Min, Wu, Shandong, and Yi, Hongwei
- Subjects
RICE ,SULFATE-reducing bacteria ,EFFECT of cadmium on plants ,EFFECT of lead on plants ,PLANT cells & tissue analysis - Abstract
Abstract The objectives of this study were to investigate the mechanism responsible for Cd and Pb immobilization by sulfate reduction to sulfide and effectiveness of decreasing Cd
2+ and Pb2+ bioavailability in culture solution and paddy soils via sulfate-reducing bacterium (SRB1-1). The SRB1-1 strain, exhibiting high resistances to Cd2+ and Pb2+ , was isolated from bulk soils in the metal(loid)-contaminated paddy field. During the culture of the SRB1-1 strain, the removal percentages of Cd2+ and Pb2+ from culture solution reached 99.5% and 76.0% in 72 h, respectively. The surface morphology and composition of metal precipitates formed by SRB1-1 strain were analyzed by transmission electron microscopy (TEM) and further confirmed to be CdS and PbS by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). When living SRB1-1 strain was applied in Cd and Pb-contaminated soils, the SRB1-1 strain could stably colonize using its resistance to rifampicin, and showed significantly impact on the bacterial community composition. Cd and Pb contents in rice grains were decreased by 29.5% and 26.2%, respectively, while Cd and Pb contents in the roots, culms, leaves, and husk were also decreased ranging from 19.1% to 43%, respectively. Due to growth in highly Cd and Pb contaminated soils, Cd content of the rice grains did not meet the standard for limit of Cd and Pb, but safe production of rice plants may be obtained in slightly or moderately metal(loid)-contaminated soils in the presence of the living SRB1-1 strain. These results indicated that the SRB1-1 strain could effectively reduce the Cd and Pb bioavailability in soils and uptake in rice plants. Our results highlighted the possibility to develop a new bacterial-assisted technique for reduced metal accumulation in rice grains, and also showed potential for effective synergistic bioremediation of SRB1-1 strain and rice plants in metal(loid)-contaminated soils. Graphical abstract fx1 Highlights • The isolated SRB1-1 strain exhibiting high resistances to Cd2+ and Pb2+ . • Characterization of precipitates confirmed metal sulfides formation on the SRB1-1. • Strain was effective in reducing Cd and Pb accumulation in rice grains. • Strain could colonize and alter bacterial community composition. [ABSTRACT FROM AUTHOR]- Published
- 2019
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