Identification of Potentially Toxic Transformation Products Produced in Polycyclic Aromatic Hydrocarbon Bioremediation Using Suspect and Non-Target Screening Approaches

Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous environmental contaminants that can be remediated through physical, chemical, or biological means. Treatment strategies can lead to the formation of PAH-transformation products (PAH-TPs) that, despite having the potential for adverse ecological and human health effects, are unregulated and understudied in environmental monitoring and remediation. Unavailability of reference standards for PAH-TPs limits the ability to identify PAH-TPs by targeted methods. This study utilized suspect and nontarget screening approaches to identify PAH-TPs produced by a bacterial culture, Rhodococcus rhodochrous ATCC 21198, using liquid chromatography-high resolution mass spectrometry. Open-source tools were used to predict biotransformation products, predict potential PAH-TP structures from mass spectra, and estimate health hazards of potential PAH-TPs. The workflow developed in this study allowed for the tentative identification of 16 PAH-TPs (confidence levels 2a to 3), seven of which were not previously detected by targeted analysis. Several new potential transformation pathways for our bacterial pure culture were suggested by the PAH-TPs, including carboxylation, sulfonation and up to three hydroxylation reactions. A computational toxicity assessment indicated that the PAH-TPs shared many hazard characteristics with their parent compounds, including genotoxicity and endocrine disruption, highlighting the importance of considering PAH-TPs in future PAH studies.

多环芳烃（Polycyclic Aromatic Hydrocarbons, PAHs）是一类广泛分布的环境污染物，可通过物理、化学或生物手段进行修复治理。其处理工艺可能会生成多环芳烃转化产物（PAH-transformation products, PAH-TPs），尽管这类产物具备潜在的生态与人体健康危害，但在环境监测与修复领域中仍未受到监管，且相关研究十分匮乏。多环芳烃转化产物参考标准的缺失，限制了靶向分析方法对其进行鉴定的能力。本研究采用可疑筛查与非靶向筛查策略，结合液相色谱-高分辨质谱联用技术，对红球菌Rhodococcus rhodochrous ATCC 21198纯细菌培养体系产生的多环芳烃转化产物进行了鉴定。本研究使用开源工具预测生物转化产物、基于质谱谱图推测潜在多环芳烃转化产物的分子结构，并评估其潜在健康危害。本研究构建的分析流程可对16种多环芳烃转化产物进行初步定性鉴定（置信水平等级2a至3），其中7种为此前未被靶向分析方法检出的新产物。基于鉴定得到的多环芳烃转化产物，本研究为该纯细菌培养体系提出了数条全新的潜在转化路径，包括羧化反应、磺化反应以及至多三次羟基化反应。计算毒理学评估结果显示，多环芳烃转化产物与其母体化合物具有诸多共同的危害特征，包括遗传毒性与内分泌干扰活性，这凸显了在未来多环芳烃相关研究中纳入多环芳烃转化产物考量的重要意义。