環境中生物氣膠之偵測 – 螢光顯微鏡、流式細胞儀與定量PCR

Abstract

對於生物氣膠的評估來說，傳統的培養方法與顯微鏡計數方式，是相當的耗時、費力與較不精準的。因此，本研究以大腸桿菌為研究對象，在實驗室詳細評估螢光顯微鏡（EFM）、流式細胞儀（FCM）與即時定量聚合酵素連鎖反應法（real-time qPCR）等三種非培養方法相互間的關係，以及其與傳統培養方法間的關係，結果顯示，FCM所測得之總細胞濃度顯著的高於EFM所測得之總細胞濃度，且兩方法所得之總細胞濃度與活性均呈高度相關，在活性部分，以FCM所測得之活性最高，而以EFM所測得之活性最低。此外，由real-time qPCR測得的DNA濃度，也與FCM與EFM所測得之總細胞濃度成良好相關，因此，本研究指出，EFM、FCM與 real-time qPCR三種非培養方法均能對微生物濃度與活性測量提供相當快速與正確的資訊。 研究結果指出，FCM為一快速與可靠的方法，因此，針對流式細胞儀輔以螢光染色的技術（FCM/FL），再進行染劑條件、染色時間與分析條件的最佳化，結果顯示SYTO-13 與YOPRO-1的組合最能提供可靠的總濃度與活性定量，本研究也成功的將FCM /FL運用在醫院廢水處理廠中曝氣池的空氣樣本與水樣本分析，整體上， FCM/FL 被證明能夠成功的定量環境空氣與水中之細菌與真菌之濃度與活性。此外，也將FCM/FL運用於生物採樣器之採樣效率的評估，結果顯示，採樣過程對微生物活性的影響的主要因素為生物氣膠的特性（脆弱與否）與用來評估活性之採樣方式，其中以衝擊瓶為對活性影響較低之採樣方式。此外，過濾方式所產生的採樣壓力，對微生物之代謝機制的影響也較對細胞膜的影響為大，而且也跟其為細菌或真菌有關係。 最後，另一種非培養方法，real-time qPCR對空氣中致病的肺結核桿菌之分析方法，也被成功的建立與應用於肺結核病人負壓病房空氣中肺結核菌之定量。此方法的檢量線範圍可達106，而肺結核病人所在病房中，其空氣中肺結核桿菌的濃度範圍為1.43 x 10 copies/m3 到 2.06 x 105 copies/m3。此外，空氣中肺結核桿菌濃度與病人痰中肺結核桿菌濃度城中度相關。整體而言，本研究所建立之非培養方法，包括EFM、FCM與real-time qPCR的結果為環境微生物與生物氣膠的研究提供了相當有利的工具，未來也能針對各種環境微生物與生物氣膠的議題，進行更進一步的研究。

Traditional culture and microscopy methods for evaluation of bioaerosols are slow, tedious, and rather imprecise. Here, using pure suspensions of E. coli, three non-culture methods, namely, flow cytometry (FCM), epifluorescence microscopy (EFM), and real-time quantitative polymerase chain reaction (real-time qPCR), were compared with a traditional culture-based method. Then, the optimal conditions of FCM with 5 different fluorescent dyes (FCM/FL) were evaluated in laboratory samples and validated to field study. In addition, FCM/FL was applied to evaluate the sampling performance of impingement and filtration with different types of fluorescent dye staining (cell membrane integrity and metabolism) and then compared with a traditional culture method (culturability). Furthermore, real-time qPCR was develop and used to measure air concentration of M. tuberculosis in a health care setting. In regard to the comparison of EFM, FCM, real-time qPCR and culture method, total cell concentrations determined using FCM were statistically higher (2.62 – 4.94 times) than those determined using EFM. In addition, EFM and FCM were highly associated for both the total cell concentration and viability. Furthermore, DNA concentrations measured by real-time qPCR with gene probe were highly associated with the total number concentrations measured by either the EFM or FCM. In summary, the three non-culture methods compared here could provide rapid and accurate information about microorganism concentrations and viabilities. For the FCM condition optimization, SYTO-13 was found to be the most suitable fluorescent dye for determining the total concentration of the bioaerosols, as well as YOPRO-1 was the most suitable for determining viability. Moreover, the established optimal FCM/FL with dyes was validated for characterizing microorganism profiles from both air and water samples from the aeration tank of hospital wastewater treatment plant. In conclusion, the FCM/FL successfully assessed the total concentration and viability for bacterial and fungal microorganisms in environmental field samples. Regarding the sampling performance of bioaerosol samplers, the bioaerosol viability during the sampling processes was highly influenced by bioaerosol characteristics (hardy or fragile), as well as by the fluorescent dyes with different physiological mechanisms. For better viability of the sampled bioaerosol, the impinger was superior to the filter. Moreover, it was found that sampling stress from filtration had more influence on the bioaerosol metabolism mechanism than cell membrane integrity. Furthermore, the differences between cell membrane integrity and the metabolism by sampling stress were found related to the bioaerosol species. By using real-time qPCR, the present study was firstly developed a quantitative assay to measure air concentration of M. tuberculosis in a health care setting. The real-time qPCR method could perform measurements of counts over 6 orders of magnitude dynamic range with a great sensitivity. The airborne M. tuberculosis concentrations were found to vary widely from 1.43 x 10 copies/m3 to 2.06 x 105 copies/m3. In addition, airborne M. tuberculosis levels, smear and culture results of sputum samples were observed to be moderately correlated. In conclusion, FCM/FL and real-time qPCR were successfully established and applied to field study. In the future, they should be powerfully tools to provide more insight in the area of bioaerosols and environmental microbiology.