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| Detoxification characteristics and mechanism of nickel and cadmium stress in maize seedlings by multifunctional bacterial consortia |
| Received:May 01, 2022 |
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| KeyWord:Bacillus safensis;Comamonas testosteroni;nickel;cadmium;maize seedling;detoxification mechanism |
| Author Name | Affiliation | E-mail | | YANG Yi | College of Resources and Environment, Jilin Agricultural University, Changchun 130118, China | | | ZHANG Yu | College of Resources and Environment, Jilin Agricultural University, Changchun 130118, China | | | YIN Qiuxia | College of Resources and Environment, Jilin Agricultural University, Changchun 130118, China | | | LI Mingtang | College of Resources and Environment, Jilin Agricultural University, Changchun 130118, China | limtdoc2008@163.com |
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| Abstract: |
| Microorganisms may reduce the toxicity of heavy metals through symbiosis with plants, which show important application value in low-carbon and green remediation of soil contaminated with heavy metals. In this study, the detoxification characteristics and mechanisms of Bacillus safensis N4 and Comamonas testosteroni ZG2 bacterial consortia against nickel (Ni) and cadmium (Cd) stress in maize seedlings were investigated using hydroponic experiments. The results showed that maize seed germination and seedling growth were significantly affected by Ni and Cd stress at the concentrations of 5-20 mg·L-1 under hydroponic conditions. However, the bacterial consortia grew and multiplied through symbiotic interactions with the maize seedlings, thus reducing the toxic effects of Ni and Cd on the growth of the seedlings, which in turn increased the plant height, primary root length, biomass, and chlorophyll SPAD values of the seedlings. Under conditions of Ni and Cd stress at concentrations of 5, 10 mg·L-1, and 20 mg·L-1, the Ni content in aboveground maize seedlings decreased by 42.2%, 37.0%, and 35.1%, respectively, and the Cd content decreased by 25.8%, 27.2%, and 28.4% respectively, compared with the content in control seedlings. The sum of the distribution proportion of more toxic forms of Ni in leaves decreased by 13.9%-21.5%, and the sum of the distribution proportion of Cd decreased by 14.7%-20.3%. The distribution proportions of Ni in leaf organelles decreased by 12.1%-17.0%, and the distribution proportions of Cd decreased by 20.7%-29.3%. Under Ni stress at concentrations of 5, 10 mg·L-1, and 20 mg·L-1, the aboveground Mg content of maize seedlings increased by 21.0%, 39.0%, and 24.1%, respectively, whereas under Cd stress at these concentrations, the aboveground Mg content of maize seedlings increased by 29.4%, 11.4%, and 35.9%, respectively. The leaf Ni and Cd content further decreased with increasing Mg concentration. These results indicate that the bacterial consortia reduce the toxic effects of Ni and Cd on maize seedlings by reducing their absorption, promoting their transformation in leaves to less toxic forms, reducing their proportions in leaf organelles, and improving the absorption of Mg in maize seedlings. |
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