耐受铅且降解菲菌群的分离、降解特性及群落结构分析

发布时间：2018-04-01 03:41

  本文选题：铅　切入点：菲　出处：《华东理工大学》2017年硕士论文

【摘要】：多环芳烃和铅是复合污染土壤中较为常见的两类污染物,目前报道多为多环芳烃生物降解功能菌株,而针对能够降解多环芳烃且耐受铅的多功能菌群报道较少。本研究从沈阳某受多环芳烃和铅等多种污染物复合污染的冶炼厂土壤中富集、分离,获得了一个具有降解菲又能耐受铅的双功能菌群。在对菌群降解菲耐受铅特性的基础上,基于高通量测序技术重点阐明了菌群的结构、功能多样性及功能基因的丰度。主要结果如下:(1)在菲和铅的选择压力下对采集污染土壤样品进行多次富集、分离得到了一个既能降解菲又能耐受铅的双功能菌群。在150 r/min,30℃培养条件下,该菌群能够在含菲(200mg/L)和铅(120mg/L)的无机盐培养基中生长,48h内可降解92.7%的菲。(2)利用高通量测序技术分析该菌群在不同污染物选择压力下的群落结构演变规律,结果显示,菌群在只含有铅的压力(S2)下多样性最高,菌群在不含污染物的环境(S1)下微生物数量最大。该菌群主要菌属包括Paracoccus、Achromobacter、Massilia、Shinella和Stenotrophomonas等。Massilia在菲的压力下(S3、S4)丰度在 18.31～30.04%,不含菲时(S1、S2)丰度在0.11～2.87%,说明Massilia只在含有菲的环境(S3、S4)中丰度高。Paracoccuy和Achromobacter在铅的压力下(S2、S4)丰度分别维持在26.94～31.82%和14.77～17.86%。综上,推测 Paracoccus、Achromobacter可能为菌群耐铅的主导菌株,Massilia可能为菌群降解菲的主导菌株。(3)利用RealtimePCR对菌群在不同污染物选择压力下,菌群降解多环芳烃的起始双加氧酶基因(RHDα)丰度和耐铅基因进行研究,结果表明,在含有菲的条件下菌群的RHDa丰度为8.18×104～2.18×105copies/mL,在不含菲的条件下菌群的RHDα丰度为2.81×102～4.99×102copies/mL,菲是决定菌群双加氧酶丰度的主要因素。同时对菌群的耐铅基因进行PCR检测,但并没有在菌群内发现已有过报道的耐铅基因。(4)在菲和铅的选择压力下筛选了两株能够在含有100 mg/L菲和60 mg/L铅的液体培养基中生长的菌。分别命名为B1和B2,对得到的两株菌进行功能验证,结果表明B1和B2均不具有降解菲的能力,但是均具有耐铅能力,B1最高能耐受100 mg/L的铅浓度,B2最高能够耐受1000 mg/L的铅浓度,而且B2在100和200 mg/L铅浓度环境中的生长比在50mg/L铅浓度中快。分离得到的菌对阐明菌群的耐铅特性有一定参考价值。
[Abstract]:Polycyclic aromatic hydrocarbons (PAHs) and lead (Pb) are two common pollutants in the soil contaminated with polycyclic aromatic hydrocarbons (PAHs). At present, polycyclic aromatic hydrocarbons (PAHs) biodegradable functional strains are mostly reported, but there are few reports on the multi-functional bacteria that can degrade PAHs and tolerate lead.In this study, a bifunctional bacteria group with phenanthrene degradation and lead tolerance was obtained from the soil of a smelter polluted by polycyclic aromatic hydrocarbons (PAHs) and lead and other pollutants in Shenyang.Based on the characteristics of phenanthrene tolerance to lead, the structure, functional diversity and functional gene abundance of phenanthrene were elucidated based on high-throughput sequencing technique.The main results are as follows: (1) under the selective pressure of phenanthrene and lead, the contaminated soil samples were enriched for many times, and a bifunctional microbial community was obtained, which could degrade phenanthrene and tolerate lead.At 150 r / min 30 鈩，

本文编号：1693838