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| Isolation and identification of Cd-and Zn-resistant bacteria in the rhizosphere of Eichhornia crassipes and their effects on Cd and Zn removal |
| Received:August 11, 2017 |
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| KeyWord:Eichhornia crassipes;heavy metal resistant bacteria;cadmium;zinc;biological enrichment |
| Author Name | Affiliation | E-mail | | GUO Shan | Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | | | GUI Heng-jun | Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | | | CHEN Pian | Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | | | ZHAO Jian-wei | Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | | | ZHOU Wen-bing | Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | | | WAN Xiao-qiong | Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | xwan@mail.hzau.edu.cn | | ZHU Duan-wei | Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | |
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| Abstract: |
| Three Cd-and Zn-resistant bacteria strains(R12, R15, and R16) were isolated from the rhizosphere of Eichhornia crassipes. Heavy metal tolerance tests indicated that the strains could tolerate up to 10 mg·L-1 and 30 mg·L-1 of Cd2+ and Zn2+, respectively, and 16S rRNA sequence analyses identified isolates R12 and R15 as Pseudomonas and isolate R16 as Stenotrophomonas. The results on the effect of strains on the removal of heavy metals during 36 h showed that the amount of Cd and Zn removed by R12 and R16 increased with time, whereas that removed by R15 first decreased and then increased, and the amount of Cd and Zn removed by all the strains reached a maximum after 36 h. Among the three strains, R16 was the most capable of removing Cd and Zn, with maximum removal amounts of 0.17 mg·kg-1 and 2.71 mg·kg-1 Cd and Zn, respectively, and maximum removal rates of 41% and 16%. Furthermore, the co-culture of E. crassipes and the rhizosphere isolates on Cd-and Zn-enriched substrate indicated that R12 and R16 mainly affect the Cd enrichment of E. crassipes by inhibiting the entry of Cd ions into the roots, whereas R15 affected Cd enrichment by regulating both the entry of Cd ions into the roots and the migration of Cd ions inside plants. The three strains all affected Zn enrichment by regulating the migration of Zn ions inside the plants. |
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