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| Identification of a cadmium-tolerant and growth-promoting Rhizobium strain and characterization of its adsorption properties for cadmium |
| Received:August 19, 2020 |
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| KeyWord:cadmium;farmland soils;bioremediation;Rhizobium pusense;tolerance;adsorption |
| Author Name | Affiliation | E-mail | | CHI Yao-wei | School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China | | | WANG Xiao-ya | School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China | | | CHU Shao-hua | School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China | | | ZHOU Pei | School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China | | | ZHANG Dan | School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China | zhdsjtu@sjtu.edu.cn |
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| Abstract: |
| Microorganisms have application potential in the bioremediation of cadmium-contaminated farmland soils. However, there is still a shortage of valuable microorganisms, and it is challenging to identify valuable candidates for cadmium bioremediation from a variety of microorganisms. In this study, the cadmium tolerance, adsorption capability, and activation capability of the plant growth-promoting microorganism AXY1 were investigated. The strain was identified as Rhizobium pusense through morphological and phylogenetic analysis, the optimum growth temperature was approximately 35℃, and the optimum growth pH was approximately 7.0. The minimal inhibitory concentration(MIC) value of the strain to cadmium was 120 mg·L-1, and the activation rate of cadmium carbonate was 9.21%. Batch adsorption experiments showed that at a pH of 7.0, biomass dosage of 1.0 g·L-1(wet weight), initial Cd2+ concentration of 10 mg·L-1, and adsorption time of 4 h, the strain showed the highest adsorption rate of 41.98%. The Langmuir isotherm model was well fitted using the data obtained from strain AXY1, thereby indicating that the strain mainly conducted monolayer biosorption. Desorption experiments showed that the strain mainly adsorbed Cd2+ by ion exchange(46.94%). Furthermore, FTIR and SEM-EDS analyses revealed the probable interactions of Cd2+ with the strain surface ligands, such as -OH, -NH, and -COOH, during surface adsorption. The results reveal that strain AXY1 has high cadmium tolerance and adsorption characteristics, which can be used for the bioremediation of cadmium-contaminated farmland soil. |
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