根际过程影响土壤中新型溴代阻燃剂的转化与效应的分子机制

Currently, great amount of novel brominated flame retardants (NBFRs) are produced and world widely used. The environmental behaviors and especially the transformation and effects of NBFRs in soils are not clear. The coupling of biochemical processes in the rhizosphere play an important role in the transformation of contaminants in soils. In order to study molecular mechanisms of the transformation and effects of NBFRs in soils influenced by the rhizosphere processes, this project selects typical NBFRs with different structures, i.e. tetrabromoethylcyclohexane (TBECH) and decabromodiphenyl ethane (DBDPE) etc, as the target compounds, and the following aspects are included: to develop an omics analytical platform for rhizosphere research, and deep insight into the biochemical process in the rhizosphere; to investigate the transformation of NBFRs in the soil and their structural selectivity, and characterize the biochemical coupling in the rhizosphere through various omics technologies such as metabonomics and metagenomics to identify the key chemical components, the dominant genera and their functional genes, and establish the metabolic pathways and network for NBFRs using multi-omics integration; to explore the responses of soil organisms to NBFRs and the soil microbial community succession, and elucidate effects of NBFRs and their metabolites on the rhizospheric micro-ecological environment; to describe the active sites on the root-soil interface and the molecular interactions of NBFRs with biomacromolecules in the rhizosphere based on the theoretical calculation to reveal the molecular mechanisms of the transformation and effects of different structural NBFRs in soils influenced by the biochemical coupling in the rhizosphere. This study will deepen the understanding of the environmental processes and biological effects of NBFRs, especially clear the regulatory roles and mechanisms of rhizosphere processes.

目前新型溴代阻燃剂生产和使用日益剧增，但是它们的土壤环境行为特别是转化与效应尚不清楚。根际生物化学耦合对土壤污染物转化起重要调控作用，本项目选取四溴乙基环己烷（TBECH）、十溴二苯乙烷（DBDPE）等不同结构类型的新型溴代阻燃剂为研究对象，以阐明根际过程影响它们转化与效应的分子机制为目标，拟搭建根际组学研究平台，实现对根际生物化学过程的深层次剖析；研究土壤新型溴代阻燃剂转化及结构选择性，基于组学方法识别根际标志性化学组分、优势菌属、关键基因，采用多组学整合，构建污染物代谢通路和网络；探讨新型溴代阻燃剂及其代谢产物胁迫下土壤生物响应与根际微生态效应，进而结合理论计算研究污染物在根‐土界面的作用位点及污染物与根际生物大分子间相互作用，最终揭示根际过程影响新型溴代阻燃剂转化与效应的生物化学耦合分子机制。本项目有助于加深对新型溴代阻燃剂环境过程与效应的认识，特别是明确根际的调控作用与机制。

新型溴代阻燃剂（NBFRs）作为传统溴代阻燃剂的替代品，是市场上新出现或最近在环境中检测到的一类含溴的有机污染物。NBFRs种类繁多，结构的多样导致了其与环境相互作用的复杂性。土壤为污染物在陆生生态环境中重要的汇，新型溴代阻燃剂的生产和使用日益剧增，但是它们的土壤环境行为特别是转化与效应尚不清楚。根际是土壤-植物系统生物化学过程最活跃的区域，根际中化学与生物多样性的分子耦合有助于阐释土壤污染物转化与效应的微观机理。但目前的研究大多停留在根际过程影响传统溴代阻燃剂土壤分布和降解的现象描述上，根际效应驱动污染物迁移转化机制的研究还依赖于方法学的进一步提升。本项目选取四溴乙基环己烷（TBECH）、十溴二苯乙烷（DBDPE）等不同结构类型的新型溴代阻燃剂为研究对象，研究了植物中新型溴代阻燃剂的吸收、传输和转化等生物过程，印证了植物载脂蛋白、细胞色素酶和谷胱甘肽硫转移酶等生物大分子与不同类型NBFRs作用的结构选择性；建立了根系分泌物分离富集以及利用正负离子模式相结合的超高分辨质谱表征根系分泌物分子组成的方法，揭示了典型植物根系分泌物的分子多样性，并探究了根系分泌物微生物代谢过程中的化学和分子转化特征；关注根-土界面的化学与生物学过程，基于高分辨质谱和高通量测序发展了根际化学与生物学耦合的组学表征新技术和方法；通过植物盆栽和微宇宙培养实验探究了根系分泌物对新型溴代阻燃剂转化与效应的作用，甄别了根际与污染物降解相关的标志性组分，筛选了根际微生物优势菌群，进一步利用共现网络分析明晰了土壤中DOM分子与微生物菌门间的互作关系，从分子水平阐释了根际生物与化学多样性耦合驱动污染物消减转化的微观机制，加深了对新型溴代阻燃剂环境过程与效应的认识，特别是明确了根际的调控作用。所得结果将会推动人们对根际科学现有问题的认识。