本研究採自中石化安順廠戴奧辛污染場址之土壤，篩選出一株純 菌微生物(Pseudomonas mendocina NSYSU) ， 其含有PCDD/Fs (Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, PCDD/Fs)土壤於實驗室進行微生物降解試驗，結果顯示約21 天即有 明顯降解結果；本研究同時觀察到該微生物能在汞濃度達50 ppm 之 戴奧辛土壤中，仍具有相當程度之耐受度，並進一步降解戴奧辛化合 物。 我更以標準品探討菌種對於戴奧辛類化合物(Dioxin like congener) 之降解效果，成功地發現這株菌種不僅對於PCDD/Fs 有降 解能力，對於戴奧辛類化合物也有明顯之降解效果。 由研究結果，明顯看出P. mendocina 菌株為「世紀之毒」找到了 解藥，開發出以生物復育改善污染環境的一種新方法。A dioxin-degrading bacterial strain Pseudomonas mendocina NSYSU was isolated from dioxin contaminated soil by selective enrichment techniques. In our previous study, P. mendocina NSYSU was found to be able to use pentachlorophenol (PCP) as its sole carbon source and energy source and was capable of completely degrading this compound. Moreover, P. mendocina NSYSU was also able to mineralize a high concentration of PCP up to 150 mg/L. In this study, P. mendocina NSYSU was investigated for its ability to degrade polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs). Results show that P. mendocina NSYSU could grow well in media containing both PCDFs and PCDDs, and was able to degrade both compounds efficiently. In this study, isotope dilution method and a high resolution gas chromatography-mass spectrometry (HRGC/HRMS) technique were applied for the analyses of PCDFs and PCDDs. Investigation results reveal that significant biodegradation of octachlorinated dibenzo-p-dioxin (OCDD) and octachlorinated dibenzofuran (OCDF) by treating with P. mendocina NSYSU resting cells was observed. The results also indicate that this bacterial strain is able to biodegrade OCDD and OCDF effectively under anoxic conditions due to its facultative anaerobic character. No accumulation of inhibitory toxic byproducts was found in this study. These findings suggest that in situ or on-site bioremediation of dioxin-contaminated soils by using indigenous microorganisms or inoculated P. mendocina NSYSU strain would be a feasible technology for field application.