Enhanced removal of polychlorinated biphenyls from alfalfa rhizosphere soil in a field study: the impact of a rhizobial inoculum.
Enhanced removal of polychlorinated biphenyls from alfalfa rhizosphere soil in a field study: the impact of a rhizobial inoculum.
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DOI：
10.1016/j.scitotenv.2009.11.031
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
Li Xu;Ying Teng;Zhen-gao Li;J. Norton;Yong-ming Luo
中科院分区：
文献类型：
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作者：
Li Xu;Ying Teng;Zhen-gao Li;J. Norton;Yong-ming Luo
多氯联苯 (PCB) 是土壤环境中的持久性污染物，持续对人类健康构成相当大的风险。需要有效且低成本的成功策略来修复受污染的土壤。包括利用植物和微生物群落促进 PCB 降解的生物修复方法具有巨大潜力，但需要在现场条件下进行进一步评估。通过田间试验评估了苜蓿（Medicago sativa L.）生长和接种共生固氮细菌（苜蓿根瘤菌）对根际土壤中多氯联苯（PCB）去除的影响。土壤的初始 PCB 含量范围为 414 至 498 µgkg−1。种植处理中根际土壤的 PCB 去除率得到增强，与未种植土壤中 PCB 水平平均降低 5.4% 相比，PCB 水平平均降低 36%；在种植后 90 天进行评估时，当植物接种共生根瘤菌时，PCB 水平进一步提高（平均降低 43%）。接种处理中植物生物量产量较高。与种植处理相比，接种处理中植物芽中的总 PCB 含量从 3.30μgkg−1 增加到 26.72μgkg−1，根中从 115.07μgkg−1 增加到 142.23μgkg−1。在接种植物的根际中观察到总异养细菌、联苯降解细菌和真菌的菌落形成单位（cfu）增加。在任何处理中，根际土壤中 PCB 的去除与植物对 PCB 的直接吸收均不显着相关，但与根际微生物区系的刺激显着相关。通过细菌核糖体序列分析观察种植和接种处理中土壤微生物群落结构的变化。一些细菌，如黄杆菌属，可能有助于 PCB 的有效降解，值得进一步研究。
Polychlorinated biphenyls (PCB) are persistent pollutants in soil environments where they continue to present considerable human health risks. Successful strategies to remediate contaminated soils are needed that are effective and of low cost. Bioremediation approaches that include the use of plants and microbial communities to promote degradation of PCB have significant potential but need further assessment under field conditions. The effects of growth of alfalfa (Medicago sativa L.) and inoculation with a symbiotic nitrogen fixing bacterium (Rhizobium meliloti) on the removal of polychlorinated biphenyls (PCB) from rhizosphere soil were evaluated in a field experiment. The initial PCB content of the soil ranged from 414 to 498µgkg−1. PCB removal for the rhizosphere soil was enhanced in the planted treatments, an average of 36% decrease in PCB levels compared to a 5.4% decrease in the unplanted soil, and further enhanced when plants were inoculated with the symbiotic Rhizobium (an average of 43% decrease) when evaluated at 90days after planting. Plant biomass production was higher in the inoculated treatment. The total PCB content was increased from 3.30µgkg−1to 26.72µgkg−1in plant shoots, and from 115.07µgkg−1to 142.23µgkg−1in roots in the inoculated treatment compared to the planted treatment. Increased colony forming units (cfu) of total heterotrophic bacteria, biphenyl-degrading bacteria and fungi were observed in the rhizosphere of inoculated plants. PCB removal from the rhizosphere soil was not significantly correlated with the direct PCB uptake by the plants in any of the treatments but was significantly correlated with the stimulation of rhizosphere microflora. Changes in the soil microbial community structure in the planted and inoculated treatment were observed by profiling of bacterial ribosomal sequences. Some bacteria, such as Flavobacterium sp., may have contributed to the effective degradation of PCB and deserve further investigation.