Coupling between Nitrogen Fixation and Tetrachlorobiphenyl Dechlorination in a Rhizobium−Legume Symbiosis
Coupling between Nitrogen Fixation and Tetrachlorobiphenyl Dechlorination in a Rhizobium−Legume Symbiosis
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根瘤菌-豆科植物共生中固氮与四氯联苯脱氯的耦合
DOI：
10.1021/acs.est.7b05667
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发表时间：
--
影响因子：
11.4
通讯作者：
Li Zhengao
中科院分区：
文献类型：
--
作者：
Wang Xiaomi;Teng Ying;Tu Chen;Luo Yongming;Greening Chris;Zhang Ning;Dai Shixiang;Ren Wenjie;Zhao Ling;Li Zhengao
Legume–rhizobium symbioses have the potential to remediate soils contaminated with chlorinated organic compounds. Here, the model symbiosis betweenMedicago sativaandSinorhizobium melilotiwas used to explore the relationships between symbiotic nitrogen fixation and transformation of tetrachlorobiphenyl PCB 77 within this association. 45-day-old seedlings in vermiculite were pretreated with 5 mg L–1PCB 77 for 5 days. In PCB-supplemented nodules, addition of the nitrogenase enhancer molybdate significantly stimulated dechlorination by 7.2-fold and reduced tissue accumulation of PCB 77 (roots by 96% and nodules by 93%). Conversely, dechlorination decreased in plants exposed to a nitrogenase inhibitor (nitrate) or harboring nitrogenase-deficient symbionts (nifAmutant) by 29% and 72%, respectively. A range of dechlorinated products (biphenyl, methylbiphenyls, hydroxylbiphenyls, and trichlorobiphenyl derivatives) were detected within nodules and roots under nitrogen-fixing conditions. Levels of nitrogenase-derived hydrogen and leghemoglobin expression correlated positively with nodular dechlorination rates, suggesting a more reducing environment promotes PCB dechlorination. Our findings demonstrate for the first time that symbiotic nitrogen fixation acts as a driving force for tetrachlorobiphenyl dechlorination. In turn, this opens new possibilities for using rhizobia to enhance phytoremediation of halogenated organic compounds.
