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Highly efficient detoxification of dinitrotoluene through overexpressing bacterial nitroreductase in switchgrass
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  • Kunlong Su,
  • Zhenying Wu,
  • Yuchen Liu,
  • Shanshan Jiang,
  • Yan Wang,
  • Chuanxiang Fu
Kunlong Su
Qingdao Institute of BioEnergy and Bioprocess Technology Chinese Academy of Sciences
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Zhenying Wu
Qingdao Institute of BioEnergy and Bioprocess Technology Chinese Academy of Sciences
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Yuchen Liu
Qingdao Institute of BioEnergy and Bioprocess Technology Chinese Academy of Sciences
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Shanshan Jiang
Qingdao Institute of BioEnergy and Bioprocess Technology Chinese Academy of Sciences
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Yan Wang
Qingdao Institute of BioEnergy and Bioprocess Technology Chinese Academy of Sciences
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Chuanxiang Fu
Qingdao Institute of BioEnergy and Bioprocess Technology Chinese Academy of Sciences
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Abstract

Dinitrotoluene (DNT) has been extensively used in manufacturing munitions, polyurethane foams, and other important chemical products. However, it is highly toxic and mutagenic to most organisms. Here, we synthesized a codon optimized bacterial nitroreductase gene, NfsI, for plant expression. The kinetic analysis indicates that the recombinant NfsI can detoxify both 2,4-DNT and its sulfonate (DNTS), while it has a 97.6-fold higher catalytic efficiency for 2,4-DNT than DNTS. Furthermore, we overexpressed NfsI in switchgrass (Panicum virgatum L.), which is a multiple purpose crop used for fodder and biofuel production as well as phytoremediation. The 2,4-DNT treatment inhibited root elongation of wild type switchgrass plants and promoted reactive oxygen species (ROS) accumulation in roots. In contrast, overexpression of NfsI in switchgrass significantly alleviated 2,4-DNT-induced root growth inhibition and ROS overproduction. Thus, the NfsI overexpressing transgenic switchgrass plant removed 94.1% 2,4-DNT after 6 days, whose efficiency was 1.7-fold higher than control plants. Moreover, the comparative transcriptome analysis suggests that 22.9% of differentially expressed genes induced by 2,4-DNT may participate in NfsI-mediated 2,4-DNT detoxification in switchgrass. Our work sheds light on the function of NfsI during DNT phytoremediation for the first time, revealing the application potential of switchgrass plants engineered with NfsI.