沉水植物降解双酚A内生菌的筛选及降解机理研究

发布时间：2018-05-24 06:01

  本文选题：狐尾藻 + 伊乐藻　； 参考：《华中师范大学》2015年硕士论文

【摘要】：双酚A(BisphenolA,简称BPA),作为一种典型的环境内分泌干扰物,广泛应用于化工行业,在生产和使用过程中通过废水或废物进入水环境,造成各种水体的污染,对水生态系统的健康稳定构成了潜在威胁。狐尾藻(Myriophyllum verticillatum)和伊乐藻(Elodeacanadensis)作为沉水植物的重要代表,能够净化水体,是水体污染修复的先锋植物。同时,广泛分布在植物体内的内生菌不仅能促进植物生长,而且可以增强植物体对环境污染物的降解,减轻污染物对植物体的毒害。因此,以狐尾藻和伊乐藻为实验材料,开展降解BPA内生菌的筛选鉴定、降解特性和降解机理的相关研究,有助于了解水生生态系统中BPA的归趋,阐明沉水植物降解BPA的内在机制,对污染水体中BPA的生物修复有指导作用。本文首次从沉水植物内生菌中分离到了降解BPA的新型菌株,并对高效菌株的降解特性、降解机理等进行探索,为环境中BPA的归趋研究及水体BPA的污染治理奠定理论基础。研究结果如下:(1)从沉水植物狐尾藻中分离筛选到了降解环境内分泌干扰物双酚A的内生细菌Mv32。通过摇瓶实验进行了菌株降解条件的优化和降解特性的探索,发现当BPA初始浓度为10 mg/L时,菌株Mv32的最佳降解条件为接种量1%,初始pH值7,温度25℃,在该条件下,菌株最大生长浓度OD600达到0.22,3d对10mg/L BPA的降解率达到47.17 ± 1.22%。经过对其形态特征和16S rRNA基因同源性序列分析,鉴定菌株Mv32为类芽孢杆菌属(Paenibacillussp.)。投加菌株Mv32(OD600=1.0,1%),对于南湖水样中BPA(10 mg/L)3d的去除率为95.78 ±0.31%。(2)从沉水植物伊乐藻中分离筛选到了降解双酚A的内生细菌Ec18,并进行了菌株降解条件的优化和降解特性的探索,发现当BPA初始浓度为10 mg/L时,菌株Ec18的最佳降解条件为接种量2%,初始pH值6,温度30℃,在该条件下,菌株最大生长浓度OD600达到0.23,3 d对10 mg/L BPA的降解率达到40.59 ±0.60%。经过对其形态特征和16S rRNA基因同源性序列分析,鉴定菌株Ec18为甲基杆菌属(Methylobacterium sp.)。菌株Ec18(OD600=1.0,1%)对投加于南湖水样中的 BPA(10 mg/L)3 d 的去除率为 68.47 ± 1.91%。(3)通过添加特异性酶抑制剂对降解菌株去除BPA影响的实验,探索可能参与BPA降解的酶。结果表明,P450酶抑制剂和漆酶抑制剂能够显著抑制菌株对BPA的降解,推测P450酶和漆酶参与了 BPA的生物转化过程。此外,利用简并引物CulAF和Cu2R扩增得到漆酶的部分序列,经过对扩增序列的分析,发现该序列与已报道漆酶氨基酸序列的覆盖率为97%,相似性高达79%,推测该序列为新型细菌漆酶基因。
[Abstract]:Bisphenol A BisphenolA (BPAA), as a typical environmental endocrine disruptor, is widely used in chemical industry. It enters the water environment through waste water or waste in the process of production and use, resulting in the pollution of various water bodies. It poses a potential threat to the health and stability of the aquatic ecosystem. Myriophyllum verticillatum and Elodea adenensis are important representatives of submerged plants, which can purify the water body and are the pioneer plants in the remediation of water pollution. At the same time, endophytic bacteria widely distributed in plants can not only promote the growth of plants, but also enhance the degradation of environmental pollutants and reduce the toxicity of pollutants to plants. Therefore, the screening and identification of endophytic bacteria for degradation of BPA and the study on degradation characteristics and degradation mechanism of BPA in aquatic ecosystem are helpful to understand the fate of BPA in aquatic ecosystem. The mechanism of degradation of BPA by submerged plants is elucidated, which can guide the bioremediation of BPA in polluted water. In this paper, a new strain for degradation of BPA was first isolated from endophytic bacteria of submerged plants. The degradation characteristics and degradation mechanism of high efficient strains were explored, which laid a theoretical foundation for the study of the fate of BPA in the environment and the pollution control of BPA in water. The results are as follows: (1) the endophytic bacteria Mv32which degrades the environmental endocrine disruptor bisphenol A was isolated and screened from the submerged plant Foxtail. The strain degradation conditions were optimized and the degradation characteristics were explored by shaking flask experiment. It was found that when the initial concentration of BPA was 10 mg/L, the optimal degradation conditions of strain Mv32 were inoculation amount 1, initial pH value 7, temperature 25 鈩，

本文编号：1927951