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標題: | 應用總體基因體學於都市污水處理廠之空氣傳播抗藥性基因之研究 A Metagenomic Framework Reveals the Dissemination Scenario of Airborne Antibiotic Resistance Genes in an Urban Wastewater Treatment Plant |
作者: | 顏睿紘 Jui-Hung Yen |
指導教授: | 蕭大智 Ta-Chih Hsiao |
關鍵字: | 總體基因體學,都市污水處理廠,曝氣池,空氣傳播抗生素抗性細菌,空氣傳播抗生素抗性基因,霧化, Metagenomics,Urban wastewater treatment plant,Aeration tank,Airborne antibiotic resistance bacteria,Airborne antibiotic resistance gene,Aerosolization, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 城市污水處理廠(UWTP)被視為抗生素抗性基因(ARGs)的重要熱點,並被認為是抗生素抗性細菌(ARB)傳播的主要人為設施之一。污染物的傳播除了可以通過UWTP的污水排放途徑外,UWTP中的曝氣池也可能透過在污水氣液界面上破裂的氣泡將其排放到大氣中。然而,目前很少有研究關注曝氣過程中空氣傳播ARGs的排放。因此本研究採用了整合序列比對(reference-based)、組裝(assembly-based)、及分群(binning-based)的總體基因體學的方法,以揭示北台灣UWTP中抗生素抗性基因的特徵。同時探討了曝氣池在排放空氣傳播ARGs時所扮演的作用,以評估空氣中ARGs的潛在風險。
基於階層式分群法,ARGs在污水和曝氣池附近收集的細懸浮微粒(PM2.5)之間顯示出相似性,而遠離處理設施的環境ARGs則具有不同的特徵和最低相對豐度(0.18 ± 0.04 ARGs/cells),顯示曝氣池確實為空氣傳播ARGs的排放源。值得注意的是,相比於ARGs在污水中的相對豐度(0.52 ± 0.01 ARGs/cells),ARGs在空氣中PM2.5的相對豐度(0.83 ± 0.11 ARGs/cells)增加了60 %。根據assembly-based的分析結果,由於高比例的空氣傳播ARGs被註釋於參與污水泡沫生成的分枝桿菌目細菌(40.9%),表明ARB較高的霧化潛勢可能是造成空氣中富集ARGs的關鍵因素之一。此外,PM2.5中抗生素抗性的輸出泵機制增加122%,意味著霧化過程中的機械力和惡劣的大氣環境篩選出了可以通過觸發輸出泵機制克服滲透壓改變的ARB。最後,綜合考量豐度、移動性和致病性的ARGs風險後,相比於污水中的風險因子(27.18 ± 0.36),其逸散的空氣傳播ARGs具有更高的風險(29.69 ± 2.96)。由於生物氣膠可以跨越地理障礙並通過人體的呼吸造成直接的暴露,其相關的移動式遺傳元件(MGEs)和致病性可能促使ARB在感染宿主後,透過基因水平轉移(HGT)加劇ARGs的傳播。 曝氣池不僅是空氣中ARGs的排放源,水和空氣間不平衡的ARGs分布也凸顯了曝氣過程中令人意外的富集效應及風險。本研究揭示了UWTP中不可忽視的ARGs空氣傳播途徑,未來應進一步進行更深入的風險評估和控制策略制定,以降低UWTP排放之生物氣膠的可能健康威脅。 Urban wastewater treatment plants (UWTPs) are considered an important hotspot of antibiotic resistance genes (ARGs). They are described as one of the major anthropogenic contributors to the dissemination of antibiotic-resistant bacteria (ARB). Apart from the transmission pathway via the effluent discharge, the aeration tanks in UWTPs might emit pollutants into the atmosphere through bubbles that burst on the air-liquid interface. Few studies, however, have reported on the emission of airborne ARGs from the aeration process. Therefore, an integrated metagenomic workflow that included reference-based, assembly-based, and binning-based analysis was conducted to uncover the comprehensive profile of ARGs in the UWTP in northern Taiwan. This research investigated the role of the aeration tank in releasing airborne ARGs and evaluated the potential risk caused by airborne ARGs. Based on a hierarchical clustering method, ARGs showed a similarity between wastewater and the PM2.5 collected near the aeration tank, whereas the ambient ARGs away from the treatment facility were found with a distinct characteristic and the lowest level (0.18 0.04 ARGs/cells). Surprisingly, there is a significant 60% surge in the relative abundance of ARGs as they transition from wastewater (0.52 0.01 ARGs/cells) to airborne PM2.5 (0.83 0.11 ARGs/cells). According to assembly-based analysis, a great proportion of airborne ARGs annotated on foam-forming bacteria under the order Mycobacteriales (40.9%) suggested that the higher atomization capabilities of ARB could be one of the crucial factors that lead to a prevalence of airborne ARGs. Additionally, increasing efflux pump mechanism in antibiotic resistance (122%) in PM2.5 implies mechanical forces during aerosolization and harsh atmospheric environment select the airborne ARB capable of overcoming the osmotic stress by triggering the efflux pump mechanism. Finally, the risk assessment of ARGs, considering abundance, mobility, and pathogenicity, uncovered the highest risk score (29.69 2.96) in the airborne ARGs emitted from the wastewater. Since bioaerosol can transport across geographical barriers and result in direct exposure to humans through inhalation, the associated mobile genetic elements (MGEs) and virulence may exacerbate the dissemination scenario of airborne ARGs. In conclusion, the aeration tank not only serves as the emission source of airborne ARGs, but the unbalanced distribution of ARGs in the aqueous and atmospheric phases also highlights the unexpected enrichment effect and exposure risk during the aerating process. This study unveils the unignorable water-to-air transmission route of ARGs in the UWTP. Further risk assessment and control strategies to protect public health from bioaerosol health threats in UWTPs should be conducted in the future. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/90794 |
DOI: | 10.6342/NTU202301766 |
全文授權: | 同意授權(限校園內公開) |
顯示於系所單位: | 環境工程學研究所 |
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