PAHs降解内生细菌在植物体内定殖及其对植物吸收PAHs的影响
毕业论文关键词：多环芳烃；内生细菌；定殖；生物降解
THE COLONIZATION OF PAH-DEGRADING ENDOPHYTIC BACTERIA AND INFLUENCE ON THE UPTAKE OF PAHs BY PLANTS
Abstract: Polycyclic aromatic hydrocarbons (PAHs) are a group of highly toxic and recalcitrant organic contaminants that are widely distributed in environments, and can be taken up by plant roots, accumulated, and translocated into plant shoots. This uptake is the major route of PAH entry into the food chain,resulting in serious threats to human health and the ecosystem. Endophytic bacteria reside in the internal tissues of healthy or symptomless plants without causing apparent harm to their hosts. Moreover, certain endophytes benefit plant growth, increase plant tolerance, and promote degradative capacity. In this study, we chosen hydroponic experiments to investigate the colonization of PAH-degrading endophytic bacterium 033 in plants and the influence of strain 033 on the uptake and degradation of PAHs by plants. The concentration of pyrene in the Hoagland are 0.1 and 0.5 mg•L-1. Culturing the wheat in the Hoagland which contain pyrene 0.5 mg•L-1,comparing with the normal wheat,the pyrene in the wheat roots which reside endophytic bacteria has reduced 14.84% and in the wheat stem has reduced 94.11% after 9 days.Culturing the wheat in the Hoagland,the pyrene is less than the Hoagland without wheat.And the wheat reside endophytic bacteria,the pyrene in the Hoagland is less than the Hoagland which culture the normal wehat. As time gose on,the 033 has reduced little in different pyrenen concentration,but the effect was not obvious.It proved that different pyrenen concentration in the Hoagland will not affect the quantity of endophytic bacterium 033.
Key words: Polycyclic aromatic hydrocarbons (PAHs); Endophytic bacteria; Colonization; Degradation
目 录
摘要1
关键词1
Abstract1
Key words1
引言1
1 材料与方法2
1.1 材料 2
1.1.1 化学试剂和培养基2
1.1.2 供试植物和菌株3
1.2 实验方法 3
1.2.1 水培实验3
1.3 分析方法 3
1.3.1 植物生物量的测定3
1.3.2 功能内生细菌的定殖数量测定3
1.3.3 霍格兰营养液中和植物体内芘含量测定3
1.4 数据处理 3
2 结果与分析3
2.1 植株体内芘的含量3
2.2 霍格兰营养液中芘的含量4
2.3 功能内生细菌033在植物体内的分布4
3 讨论 5
3.1菌株033对植物吸收代谢芘的影响5
3.2 霍格兰营养液中不同浓度的芘对细菌033定殖的影响 5
4 展望5
致谢5
参考文献6
PAHs降解内生细菌在植物体内的定殖及其对植物吸收PAHs的影响
引言：多环芳烃(Polycyclic aromatic hydrocarbons, PAHs)是土壤环境中普遍存在的一类持久性有机污染物，并具有致癌、致畸、致突变的“三致”作用[1]。由于PAHs疏水性强、难于降解、易在土壤中累积等特点，其被植物吸收积累后，可通过食物链富集，严重危害人体健康[2-4]。因此，如何规避植物体内PAHs污染风险，保障农产品安全和生态系统的可持续发展已经成为研究者关注的焦点问题之一。
近年来，国内外学者试图通过添加外源化学制剂等来调控植物对PAHs等有机污染物的吸收、积累和代谢作用[5-7]。Gao等[6]报道，添加低浓度非离子表面活性剂Brij35提高了植物体内菲、芘的含量和富集系数，而高浓度Brij35则抑制了植物吸收。占新华等[7]研究表明，外源水溶性有机物(DOM)能明显地促进小麦对菲的吸收和富集作用。然而，外源化学制剂本身具有毒性，且对环境造成二次污染[8]；此外，这些制剂对植物吸收有机污染物的调控作用往往只能在特定的环境条件下方能有效，其广谱功效尚未得到证实。因此，研究者提出利用植物体内的微生态系统，即植物-微生物联合体系调控植物对PAHs等有机污染物的吸收代谢作用[9]。