Model-aided Design and Integration of Functionalized Hybrid Nanomaterials for Enhanced Bioremediation of Per-and Polyfluoroalkyl Substances (PFASs)

项目总结 全氟和多氟烷基物质(PFAS)对环境的污染是一个主要的公共卫生问题 因为接触这些持久性化学物质会产生广泛的毒性影响。 由于C-F键的稳定性很强，几乎没有发现能够降解的微生物 PFASs，生物降解非常缓慢且不完全。通常，生物修复的努力导致了 在环境中保持有毒、持久性和高流动性的短链全氟辛烷磺酸。现代非生物 处理技术可以更有效，但对能源的要求非常高。因此，本研究 提出了一种创新的修复策略，该策略使用催化混合动力将前处理步骤结合起来 利用丰富的微生物群落实现纳米材料的生物降解，实现更高效、更完整 销毁全氟辛烷磺酸，不会产生有毒副产物。多功能还原氧化石墨烯-金属 能够催化全氟辛烷磺酸的脱氟和氧化的纳米杂化材料(例如rGO-nZVI-Ti02)将是 合成并表征了它们将高度稳定的全氟辛烷磺酸转化为更易生物降解的高效性 表格。纯培养物(如脱卤球菌属)和脱盐杆菌属(Dehalbacter sp.)和收集的富含微生物的联合体 来自全氟辛烷磺酸污染场地和厌氧废水处理厂将被用于降解不同的 对PFASs的类型和去除效果进行测量。使用元基因组学和转录组学工具， 负责降解的微生物、它们的功能特征和被转录的基因 在除氟过程中将被识别。在前处理反应的每个步骤和过程中形成的副产物 微生物降解全氟辛烷磺酸的过程将用高效液相色谱进行表征。 分辨率质谱学，~(19)F-核磁共振波谱和离子色谱，以获得 关于全氟辛烷磺酸转化产物的特性、降解动力学和质量平衡的信息。 分子模拟将被用来对特定的PFAS表面和PFAS酶进行机理上的洞察 互动。PFASs的结构特征(如支化、链长、头基类型)对 系统地评估它们的生物降解性，首先通过分子模拟，然后通过实验。 验证。对PFASs降解副产物与In的化学表征的认识 电子定点突变将有助于酶活性的调整和新细菌的发现 它们是自然环境中全氟辛烷磺酸的高效降解者。这些见解将指导系统化的 设计高效的纳米强化生物修复系统以完全微生物降解全氟辛烷磺酸。

PROJECT SUMMARY Environmental contamination by per- and polyfluoroalkyl substances (PFASs) is a major public health concern because of the wide range of toxic effects that have been associated with exposure to these persistent chemicals. Due to the strong stability of the C-F bond, very few microorganisms have been found capable of degrading PFASs, and the biodegradation is very slow and incomplete. Often, bioremediation efforts result in the formation of shorter chain PFASs that remain toxic, persistent, and highly mobile in the environment. Current abiotic treatment technologies can be more effective, but have very high energy requirements. Therefore, this research proposes an innovative remediation strategy that couples a pre-treatment step using catalytic hybrid nanomaterials with biodegradation using enriched microbial communities to achieve more efficient and complete destruction of PFASs without the formation of toxic by-products. Multifunctional reduced graphene oxide-metallic nanohybrids (e.g. rGO-nZVI-TiO2) that are capable of catalyzing defluorination and oxidation of PFASs will be synthesized and characterized for their efficiencies in converting highly stable PFASs to more biodegradable forms. Pure cultures (e.g. Dehalococcoides sp. and Dehalobacter sp.) and enriched microbial consortia collected from PFAS-contaminated sites and anaerobic wastewater treatment plants will be used to degrade different types of PFASs and measure their removal efficacy. Using metagenomic and transcriptomic tools, the microorganisms responsible for degradation, their functional characteristics, and the genes being transcribed during defluorination will be identified. By-products formed at each step of the pre-treatment reaction, and during the course of the microbial degradation of PFASs will be characterized using liquid chromatography with high- resolution mass spectrometry, 19F-nuclear magnetic resonance spectroscopy, and ion chromatography to obtain information on the identities of PFASs transformation products, degradation kinetics, and mass balance. Molecular modeling will be used to bring mechanistic insight into specific PFAS-surface and PFAS-enzyme interactions. The effect of the structural features of PFASs (i.e. branching, chain-length, type of head groups) on their biodegradability will be systematically evaluated, first by molecular modeling, and then by experimental validation. Knowledge from the chemical characterization of PFASs degradation by-products combined with in silico site-directed mutagenesis will facilitate the tuning of enzymatic activities and discovery of novel bacteria that are efficient degraders of PFASs from the natural environment. These insights will guide the systematic design of highly efficient nano-enhanced bioremediation systems for complete microbial degradation of PFASs.