碳纳米材料对紫花苜蓿根际降解多环芳烃的调控机制研究

Carbon nanomaterials are a new generation of materials at the nanoscale. The premise for the application of nanomaterials in rhizoremediation of contaminated soil by polycyclic aromatic hydrocarbons (PAHs) is to understand how to regulate the rhizodegradation of PAHs, but the specific mechanism remains unclear at present. Through previous study, the applicant found that carbon nanomaterials had the potential to enhance rhizoremediation. With alfalfa used as experimental plant, the rhizodegradation process of PAHs taken as the core, the regulation of root exudates by carbon nanomaterials considered as the pointcut, this project will centre on the relation among carbon nanomaterials, root exudates and PAHs bioavailability as well as soil microorgnisms. Applying technological means including metabonomics analysis, DNA-based Stable Isotope Probing, high throughout sequencing through Illumina Miseq, and real-time PCR, the project will carry out culture experiments with sand, microcosm and root box with multilayers to systematically study the chemical and microbiological effects generated by carbon nanomaterials themselves and the root exudates influenced by carbon nanomaterials under the stress of PAHs，and conduct coupling analysis on the relation between these effects and the degradation of PAHs, in order to reveal the chemical and microbiological mechanisms of rhizodegradation regulated by carbon nanomaterials. The research results will provide scientific basis for the application of nanomaterials in the remediation of PAHs contaminated soil.

碳纳米材料是一种处于纳米量级的新一代材料。将纳米材料应用于PAHs污染土壤根际修复的前提是要了解其如何调控PAHs的根际降解，但是目前具体的机制尚不清楚。申请者前期研究发现，碳纳米材料具有强化根际修复的潜力。本项目拟采用紫花苜蓿为供试植物，以PAHs的根际降解过程为核心，以碳纳米材料对根系分泌物的调控为切入点，围绕碳纳米材料-根系分泌物-PAHs生物有效性和土壤微生物的关系展开，采用代谢组学分析、稳定同位素核酸探针、Illumina Miseq高通量测序及荧光定量PCR等技术手段，通过砂培、微宇宙培养及多隔层根箱培养试验，系统研究PAHs胁迫条件下，碳纳米材料通过影响根系分泌物介导的化学和微生物学效应及其自身的化学和微生物学效应，耦合分析这些效应与PAHs降解的关系，以揭示碳纳米材料调控PAHs根际降解的化学和微生物学机制。研究结果将为纳米材料在PAHs污染土壤修复领域的应用提供科学依据。

纳米材料在环境生物修复领域表现出良好的应用潜力，但其对污染土壤生物修复的强化效果及作用机制研究仍存在较大不足，特别是其对根际降解有机污染物的调控机制尚不清楚。基于此，本项目以紫花苜蓿为供试植物，以碳纳米管、石墨烯和纳米碳等为供试碳纳米材料，首先研究了碳纳米材料对紫花苜蓿根际降解PAHs的影响，发现多壁碳纳米管和功能化石墨烯在一定含量下可以显著促进紫花苜蓿根际对PAHs的降解去除；随后，深入解析了多壁碳纳米管和磺化石墨烯促进紫花苜蓿根际降解PAHs的动态过程，并采用高通量测序和宏基因组等研究方法和手段，阐明了其对根际微生物组的调控作用，明确了典型碳纳米材料促进根际土壤中PAHs降解微生物的富集是促进PAHs降解的主要驱动因素；基于代谢组学分析，发现多壁碳纳米管明显回调了多环芳烃胁迫降低的有机酸和氨基酸等代谢物的含量，通过促进三羧酸循环、乙醛酸和二羧酸代谢以及氨基酸代谢等途径，增强了紫花苜蓿抵御芘胁迫的能力；进一步研究了碳纳米材料与特异性根系分泌物对土壤中PAHs降解的协同促进效应，揭示了典型碳纳米材料通过调控根系分泌物的组成和含量，促进根际土壤中降解微生物群落的富集，从而促进紫花苜蓿根际降解PAHs的化学-微生物学机制；发现了典型碳纳米材料对PAHs高效降解菌生长及生物膜形成的促进作用，并依此制备了纳米固定化微生物菌剂，探明了其对PAHs污染土壤的强化修复效应及机制；建立了PAHs污染土壤的纳米材料强化根际修复方法和纳米固定化微生物强化修复方法，为发展纳米材料在有机污染土壤修复中的应用提供了科学依据和方法支撑。