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| The promoting effect of phosphorus-solubilizing bacteria on remediation of cadmium-contaminated saline soil by Suaeda salsa |
| Received:January 15, 2018 |
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| KeyWord:phosphorus-solubilizing bacteria;Suaeda salsa;root exudates;saline soil;Cd;remediation |
| Author Name | Affiliation | E-mail | | LIN Xin | School of Environment, Jinan University, Guangzhou 510632, China | | | WANG Li-li | School of Environment, Jinan University, Guangzhou 510632, China | | | YANG Ping | School of Environment, Jinan University, Guangzhou 510632, China | | | LI Qu-sheng | School of Environment, Jinan University, Guangzhou 510632, China | liqusheng@21cn.com | | XU Zhi-min | School of Environment, Jinan University, Guangzhou 510632, China
School of Life Science and Technology, Jinan University, Guangzhou 510632, China | | | WEI Jia | School of Environment, Jinan University, Guangzhou 510632, China | | | ZHOU Ting | School of Environment, Jinan University, Guangzhou 510632, China | |
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| Abstract: |
| In order to improve the efficiency of phytoremediation on cadmium-contaminated saline soil and to explore the effect of phosphorus-solubilizing bacteria on plant growth and cadmium uptake in contaminated soil, root exudates of Suaeda salsa were collected from a sterile hydroponic(with 2% NaCl) culture. Five cadmium-and phosphorus-solubilizing isolates were cultivated using the exudates as a unique carbon source in medium. Their growth curves were obtained by determining their OD values. Escherichia grew faster and had stronger cadmium-and phosphorus-solubilizing abilities than the rest of the isolates(P<0.05). Herein, its changes in ability to solubilize P and Cd from Ca3(PO4)2 and CdCO3, respectively, and in its metabolic products in three concentrations of NaCl medium(0.3, 6, 12 g·L-1) were studied using a shaking flask experiment. A pot experiment was also conducted in sewage-irrigated garden soil(1.37 mg·kg-1 Cd) pretreated with three concentrations of NaCl(0, 4, 8 g·kg-1). The promoting effect of Escherichia on remediation of cadmium-contaminated saline soil by Suaeda salsa was investigated. The results showed that Escherichia produced 80.19, 78.79 mg·L-1, and 77.54 mg·L-1 dissolved phosphorus and 17.84, 17.30 mg·L-1, and 19.73 mg·L-1 dissolved cadmium, respectively, with the 0.3, 6 g·L-1, and 12 g·L-1 salt concentration treatments. This shows that an increasing concentration of salt had no effect on P release and promoted Cd release. There was obvious change in the composition of metabolites of Escherichia under the different salt treatments. With the 0.3, 6 g·L-1, and 12 g·L-1 salt treatments, 5, 10 kinds, and 13 kinds of organic acids and 4, 8 kinds, and 8 kinds of amino acids were released, respectively. The valine content increased significantly with increasing salt(P<0.05). In the pot experiment, biomass and Cd content in the rhizosphere soil solution of Suaeda salsa with bacterial inoculation treatment increased significantly compared with the control(P<0.05), with 4 g·kg-1 salt treatment. The total mobilized Cd in the rhizosphere soil increased by 3.17-fold. The average enrichment coefficient of the total and DTPA-extractable Cd increased by 260%. These results suggest that Escherichia grew normally and promoted the accumulation of Cd in Suaeda salsa under salt stress. This study provides some useful information regarding remediation of cadmium-contaminated saline soil. |
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