多溴聯苯醚在厭氧混合菌群中之降解及其對菌群結構之影響

Abstract

多溴聯苯醚 (Polybrominated diphenyl ethers, PBDEs) 為溴化阻燃劑 (Brominated flame retardant, BFRs) 的一種，被廣泛的用於電子設備、泡綿家具、建材及紡織上的阻燃劑，本研究目的，為了解在 PBDEs 降解過程中，對於底泥菌群結構之影響。本研究利用以台灣台南縣三爺公溪口與桃園縣南崁溪成功橋下之底泥，進行增殖培養底泥中的菌群之後，去除底泥並增殖培養菌群，再添加多溴聯苯醚至此菌液中測其降解。 在為期70天之實驗中，對 0.1 μg mL-1之四溴聯苯醚 (BDE 47)、五溴聯苯醚 (BDE 99，BDE 100)、六溴聯苯醚 (BDE 153，BDE 154) 進行降解，以氣相層析儀分析殘量。再使用 PCR 技術放大 16s rDNA 後，以 DGGE 分析菌群結構之變化。 由降解實驗結果顯示，BDE 47 在南崁溪底泥菌群中的殘量從第 49 天至第 56 天自78.64% 下降至 22.41%，並於第 63 天低於偵測極限；其餘受測的多溴聯苯醚並無觀察到明顯的降解。DGGE 聚類分析的結果顯示，能夠降解 BDE 47 的南崁溪菌群於第 42 天與第 70 天之菌群相似度為 66%；其餘受測菌群，第42天與第70天之菌群相似度可達 45%。 由本研究結果推論，南崁溪的本土厭氧混合菌群可降解四溴連苯醚 BDE 47，二仁溪的本土厭氧混合菌群對受測之五種皆無明顯之降解能力；然而在 BDE 47 降解前後的菌群結構，變化程度差異並不明顯，是故對於降解能力與菌群結構變化之交互關係，仍需進一步的實驗加以探討。

PBDEs, one of brominated flame retardants (BFRs), which are bioaccumulated and biomagnified in the environment widely used on electronic equipment, foam furniture and textile. This research is to investigate the effects of polybrominated diphenyl ethers (PBDEs) on the microbial community changes during the degradation. The sediments used in this research were collected from Er-Ren River and Nan-Kan River basin in Taiwan, after the microbial communities were enriched, remove the sediment and enriched the microbial communities again. To measure the biodegradation of PBDEs, 0.1 μg mL-1 PBDEs congeners (BDE 47, 99, 100, 153 and 154) were added into cultures contained medium separately and incubate at 30oC for 70 days. Residues were determined by GC-ECD. Denaturing gradient gel electrophoresis (DGGE) was used for analyzing the microbial community structures during PBDEs degradation periods. According to the results, only BDE 47 is degraded which decrease in microbial community from Nan-Kan River basin. During day 49 to day 56, BDE 47 residues were degrade from 78.64% to 22.41%, and was undetectable on day 63; other PBDEs were not degrade obviously. DGGE analysis of the 16S rDNA fragments obtain from BDE 47 added Nan-Kan River basin cultures indicated that the community similarity between day 42 and day 70 was 66%; the lowest similarity among other PBDEs added cultures between these two days was 45%. From this result, microbial community from Nan-Kan River basin has the ability to degraded BDE 47, and microbial community from Er-Ren River doesn’t. Both these two microbial community can’t degrade other PBDEs used in this experiment. However, the community changes before and after the degradation is not significantly. The relationship between the ability of degradation and microbial community changes still needs further researches to indicate.