深海多环芳烃降解菌Celeribacter indicus P73~T降解荧蒽和菲的机制研究
发布时间：2018-11-16 11:15
【摘要】：多环芳烃是一类在环境中分布十分广泛的持久性有机污染物,具有潜在的致癌、致畸、致突变作用,对生态环境和人类生命健康具有巨大的危害。菲具有多环芳烃的典型结构——K区和湾区,是研究低分子量多环芳烃降解机理的模式化合物。荧蒽是一种高分子量多环芳烃,其分子结构与一些重要的环境污染物如二苯并呋喃、咔唑和二苯并二VA英等结构相似,常被作为高分子量多环芳烃降解研究的模式化合物。本实验室从西南印度洋深海沉积物样品中分离获得一株多环芳烃降解菌Celeribacter indicus P73~T,能够高效降解菲和荧蒽等多种多环芳烃。本文以C.indicus P73~T为研究对象,通过基因组分析、转录组分析、功能基因研究和代谢物检测等多种手段解析其降解荧蒽和菲的分子机制和代谢途径,为认识其环境作用及开发相关生物修复技术提供支撑。采用Solexa双末端测序技术获得了C.indicus P73~T的全基因组序列。C.indicus P73~T全基因组共含有4,969,388碱基对(bp),其中包括一个环形染色质体(4,529,105 bp)和五个质粒(大小范围7053 155,183 bp),基因组DNA的G+C含量为65.74%。C.indicus P73~T基因组包含4827个蛋白编码基因、2套r RNA基因(5S r RNA、16S r RNA和23S r RNA各2个)和48个t RNA基因,平均基因长度为909 bp,基因编码密度为88.3%。在4827个蛋白编码基因中,有3908个基因(80.96%)归为22个不同的蛋白质直系同源簇。C.indicus P73~T基因组中包含至少138个多环芳烃降解基因,其中包括6个苯环羟基化双加氧酶基因和9个苯环裂解双加氧酶基因。经基因敲除和功能验证,P73_0346是负责荧蒽、萘、菲等多环芳烃第一步双加氧反应的苯环羟基化双加氧酶大亚基,是第一个被发现的荧蒽-7,8-双加氧酶,也是甲苯/联苯双加氧酶家族(类群IV)中第一个荧蒽双加氧酶。通过基因组岛和基因水平转移的预测分析,发现C.indicus P73~T通过基因水平转移等方式获取了一些多环芳烃降解基因,增强了多环芳烃降解能力。对C.indicus P73~T转录组进行了测序分析,发现1184个基因(24.5%)在荧蒽诱导培养时发生差异表达,其中975个基因(20.2%)上调表达。通过基因组和转录组联合分析,发现至少有110个基因可能参与了荧蒽的降解过程,其中包括趋化、信号感应和传导、调控、转运和降解等过程的相关基因。采用气相色谱-质谱联用技术检测到C.indicus P73~T降解荧蒽的4种重要中间代谢产物:1-二氢-苊酮、二氢苊醌、1,2-二羟基苊烯和1,8-萘二甲酸。据此推测C.indicus P73~T通过C-7,8双加氧途径降解荧蒽。同时综合基因组分析结果、转录组分析结果、功能基因研究结果和文献报道,推测了C.indicus P73~T降解荧蒽的代谢途径。C.indicus P73~T降解荧蒽的代谢途径是经由7,8-二羟基荧蒽间位裂解反应的C-7,8双加氧途径,中间代谢产物邻苯二甲酸和原儿茶酸通过β-酮己二酸途径最终进入三羧酸循环彻底降解。同时,荧蒽C-7,8双加氧途径是C.indicus P73~T降解荧蒽的唯一代谢途径,因此,C.indicus P73~T可以作为一株研究荧蒽C-7,8双加氧途径的模式菌株。采用气相色谱-质谱联用技术检测到C.indicus P73~T降解菲的2种重要中间代谢产物:1-萘酚和1-羟基-2-萘甲酸,并据此推测C.indicus P73~T通过C-3,4双加氧途径降解菲。综合代谢组分析结果、基因组分析结果、基因功能研究结果以及已报道的菲代谢途径,推测了C.indicus P73~T降解菲的C-3,4双加氧途径:首先在菲C-3,4位发生双加氧反应,随后逐步氧化形成1-羟基-2-萘甲酸,并进一步脱羧生成1-萘酚。1-萘酚等毒性代谢物在C.indicus P73~T菌体和培养基中大量积累,导致菌体生长微弱。C.indicus P73~T是Celeribacter属的一个新种,能够广谱、高效地降解多种多环芳烃,在石油泄漏、多环芳烃污染等海洋受污染环境的生物修复中具有较大的应用前景。本文研究解析了C.indicus P73~T降解荧蒽和菲的分子机制和代谢途径,能够为环境中荧蒽和菲污染的生物修复技术提供理论指导。
[Abstract]:Polycyclic aromatic hydrocarbon is a kind of persistent organic pollutant which is widely distributed in the environment, has potential carcinogenic, teratogenic and mutagenic effects, and has great harm to the ecological environment and human health. Phenanthrene has a typical structure of polycyclic aromatic hydrocarbons, the K region and the Gulf region, and is a mode compound for studying the degradation mechanism of low molecular weight polycyclic aromatic hydrocarbons. It is a kind of high molecular weight polycyclic aromatic hydrocarbon, and its molecular structure is similar to some important environmental pollutants, such as dibenzol and dibenzo-dibenzo-dibenzo-2-VA, and is often used as a mode compound for the degradation of high-molecular-weight polycycloaromatics. The laboratory isolated from the deep-sea sediment sample of the southwest Indian Ocean to obtain a multi-cyclic aromatic hydrocarbon degrading bacterium, Celeribacter indicius P73-T, and can effectively degrade various polycyclic aromatic hydrocarbons such as the phenanthrene and the polyaromatic hydrocarbon. In this paper, C. indicus P73-T is used as the research object, and the molecular mechanism and the metabolic pathway of the degradation of the phenanthrene and phenanthrene are analyzed by a variety of means such as genome analysis, transcription group analysis, functional gene research and metabolite detection, so as to provide support for the recognition of its environmental effect and the development of related bioremediation technology. The whole genome sequence of C. indicius P73-T was obtained by using the Solexa double-terminal sequencing technology. .C.indicus P73~T鍏ㄥ熀鍥犵粍鍏卞惈鏈，
本文编号：2335362
[Abstract]:Polycyclic aromatic hydrocarbon is a kind of persistent organic pollutant which is widely distributed in the environment, has potential carcinogenic, teratogenic and mutagenic effects, and has great harm to the ecological environment and human health. Phenanthrene has a typical structure of polycyclic aromatic hydrocarbons, the K region and the Gulf region, and is a mode compound for studying the degradation mechanism of low molecular weight polycyclic aromatic hydrocarbons. It is a kind of high molecular weight polycyclic aromatic hydrocarbon, and its molecular structure is similar to some important environmental pollutants, such as dibenzol and dibenzo-dibenzo-dibenzo-2-VA, and is often used as a mode compound for the degradation of high-molecular-weight polycycloaromatics. The laboratory isolated from the deep-sea sediment sample of the southwest Indian Ocean to obtain a multi-cyclic aromatic hydrocarbon degrading bacterium, Celeribacter indicius P73-T, and can effectively degrade various polycyclic aromatic hydrocarbons such as the phenanthrene and the polyaromatic hydrocarbon. In this paper, C. indicus P73-T is used as the research object, and the molecular mechanism and the metabolic pathway of the degradation of the phenanthrene and phenanthrene are analyzed by a variety of means such as genome analysis, transcription group analysis, functional gene research and metabolite detection, so as to provide support for the recognition of its environmental effect and the development of related bioremediation technology. The whole genome sequence of C. indicius P73-T was obtained by using the Solexa double-terminal sequencing technology. .C.indicus P73~T鍏ㄥ熀鍥犵粍鍏卞惈鏈，
本文编号：2335362
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