| 摘要: | 烷基苯酚聚氧乙烯醇類(Alkylphenol polyethoxylates, APEOn)化合物常用於做為界面活性劑和清潔劑，其種類包括壬基苯酚聚氧乙烯醇(Nonylphenol polyethoxylates, NPEOn)和辛基苯酚聚氧乙烯醇(Octylphenol polyethoxylate, OPEOn)，APEOn生物降解代謝產物包括壬基苯酚(Nonylphenol, NP)和辛基苯酚(Octylphenol, OP)及其帶有一單位氧乙烯醇的代謝物如Nonylphenol mono-ethoxylate (NPEO1)和Octylphenol mono-ethoxylate (OPEO1)被推論具有生物荷爾蒙性質，此代謝物在環境中當濃度到達一定程度時，就足以對野生動物和人類之內分泌功能造成干擾作用，且此類物質之毒性及難分解性較未分解前之界面活性劑為高，因此，世界許多國家已將APEOn類化合物列為管制使用之對象。由於OPEOn之烷基結構較為簡單，且OP之雌激素效應為NP之10至20倍，因此，本研究以OPEOn為對象，用以評估OPEOn及其代謝產物之生物復育效果，五株從土壤和底泥篩出之OPEOn分解菌中，以30℃，200 rpm恆溫振盪之斜面培養，以OPEOn為唯一碳源，進行五菌株水溶液中生長和OPEOn生物降解效率之評估。土壤縮模(Microcosm)則被用以模擬生物復育程序以評估生物復育之效果，三株外添加菌Pseudomonas nitroreducens TX1、Pseudomonas putida TX2和Pseudomonas sp. OP2亦被添加於土壤中以降解OPEOn及其代謝產物。研究結果顯示，五株環境中所篩出之OPEOn分解菌中，菌株E獲得最大比生長率0.56 h-1和95% OPEOn初級降解效果，菌株A比其他四菌株更能於高OPEOn濃度中生存。對五菌株而言，在5,000 mg/L OPEOn-MSB medium中，1,200 mg/L至1,600 mg/L之(NH4)2SO4濃度，為較適切之氮源使用量，pH 7則為最適之生長環境條件，關於OPEOn及OP之生物復育方面，OPEOn及其代謝產物確實可經由添加外添加菌和土壤原生菌之作用而降解，在91天的實驗操作中，有98%以上的OPEOn達成初級分解，約75%之OP在縮模土壤生物復育過程中降解。直接添加菌株Pseudomonas sp. OP2，可於70天的實驗操作中，提高約25%之OP降解效果。OPEOn土壤中降解路徑分析則找到三種新的代謝產物，包括octylcatechol，butylphenol Polyethoxylates (1 to 3 ethoxylate unit)和phenol。微生物菌相分析顯示菌株Brucellaceae bacterium, Stenotrophomonas maltophilia and Aeromonas hydropila在土壤中之優勢表現，而外添加菌株TX1，TX2及OP2皆能在添加之後，成為縮模土壤中之優勢菌種。本研究證實OPEOn及其代謝產物透過外添加菌添加之生物復育程序為一可行之方法。 Alkylphenol polyethoxylates (APEOn) including nonylphenol polyethoxylates (NPEOn) and octylphenol polyethoxylates (OPEOn) were used very commonly in surfactants and detergents. The biodegradation metabolites of APEOn including nonylphenol (NP), octylphenol (OP), nonylphenol mono-ethoxylate (NPEO1) and octylphenol mono-ethoxylate (OPEO1) are supposed to imitate the natural hormones. The levels of these metabolites present in the environment may be sufficient to disrupt endocrine function in wildlife and humans. These compounds are more toxic and resistant to biological degradation than the parental surfactants. Therefore, the use of APEOn has been limited in many countries. Since the simpler structure of the alkyl group than NPEOn, and the OP obtain10 to 20 fold higher of the estrogenic effect than NP, the OPEOn was dealing with this study to be the target compound for the evaluation of OPEOn and its metabolites bioremediation efficiency. Five strain of OPEOn degrader which isolated from soil and sediments were evaluated in the aquatic medium using OPEOn as the sole carbon source at 30℃, 200 rpm shaking culture. The microcosms assimilated the bioremediation were employed for the evaluation of OPEOn and OP bioremediation efficiency. The exogenous strains of Pseudomonas nitroreducens TX1, Pseudomonas putida TX2, and Pseudomonas sp. OP2 were also utilized to biodegraded OPEOn and metabolites in the soil. The results of this study showed, for five strains of OPEOn degrader, strain E obtained the maximum specific growth rate of 0.46 h-1 and degradation efficiency of 95% for OPEOn primary biodegradation. Strain A can be sustained in the highest OPEOn concentration than the other four strains. The nitrogen source of (NH4)2SO4 with the concentration of 1,200 to 1,600 mg/L and pH 7 were also the feasible growth condition for the five strains in 5,000 mg/L OPEOn-MSB medium. Regarding to the bioremediation of OPEOn and OP, the exogenous degrader and soil indigenous microorganisms approved the OPEOn and metabolites biodegradation in the soil. In 91 days bioremediation period, over 98% of OPEOn and 75% of OP have been degraded in the soil. By the OP directly bioremediation process, around 25 % OP could be degraded in the soil in 70 days bioremediation period by the addition of the exogenous Pseudomonas sp. OP2. The analyzed of OPEOn biodegradation pathway in the soil was also conducted and three novel intermediates including octylcatechol, butylphenol polyethoxylates with 1-3 ethoxylate unit, and phenol had been found. The analysis of bacterial community in the soil was shown the predominant strains of Brucellaceae bacterium, Stenotrophomonas maltophilia and Aeromonas hydropila in the soil. Additionally, all three exogenous bacteria of strain TX1, TX2, and OP2 were also predominant in the soil. The bioremediation of OPEOn and its metabolites by the exogenous strains were therefore noted in this research. |
