Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium.
Environ Sci Technol. 2009 Dec 15;43(24):9413-8. doi: 10.1021/es901997z.
Phytoremediation of volatile organic contaminants often proves not ideal because plants and their rhizosphere microbes only partially degrade these compounds. Consequently, plants undergo evapotranspiration that contaminates the ambient air and, thus, undermines the merits of phytoremediation. Under laboratory conditions, endophytic bacteria equipped with the appropriate degradation pathways can improve in planta degradation of volatile organic contaminants. However, several obstacles must be overcome before engineered endophytes will be successful in field-scale phytoremediation projects. Here we report the first in situ inoculation of poplar trees, growing on a TCE-contaminated site, with the TCE-degrading strain Pseudomonas putida W619-TCE. In situ bioaugmentation with strain W619-TCE reduced TCE evapotranspiration by 90% under field conditions. This encouraging result was achieved after the establishment and enrichment of P. putida W619-TCE as a poplar root endophyte and by further horizontal gene transfer of TCE metabolic activity to members of the poplar's endogenous endophytic population. Since P. putida W619-TCE was engineered via horizontal gene transfer, its deliberate release is not restricted under European genetically modified organisms (GMO) regulations.
植物修复挥发性有机污染物的效果往往并不理想，因为植物及其根际微生物只能部分降解这些化合物。因此，植物会通过蒸腾作用将污染物排放到周围空气中，从而破坏了植物修复的优点。在实验室条件下，配备适当降解途径的内生细菌可以提高植物体内挥发性有机污染物的降解能力。然而，在工程内生菌成功应用于田间尺度的植物修复项目之前，还必须克服几个障碍。在这里，我们报告了首次在 TCE 污染场地生长的杨树原位接种 TCE 降解菌 Pseudomonas putida W619-TCE。在田间条件下，用菌株 W619-TCE 进行原位生物强化可将 TCE 的蒸腾作用减少 90%。这一令人鼓舞的结果是在 P. putida W619-TCE 作为杨树根内生菌建立和富集的基础上，以及通过将 TCE 代谢活性进一步横向转移到杨树内生生境种群的成员中实现的。由于 P. putida W619-TCE 是通过水平基因转移工程改造的，因此其故意释放不受欧洲转基因生物（GMO）法规的限制。
