| 摘要: | 環境中的多氯聯苯(PCB)可經厭氧生物降解進行還原性脫氯作用。PCB脫氯菌群是以複合菌群形式存在，難以分離培養研究，截至目前為止仍未有PCB厭氧分解菌被分離出來。本研究應用環境分子生物技術(DGGE菌群指紋譜、clone library、FISH)來分析2,4',5-CB、2,2',5,5'-CB和2,2',4,5,5'-CB為基質馴養之混和菌群，以探討PCB厭氧降解菌群結構。研究結果顯示，不同厭氧狀態下馴養的降解菌群整體上有不同的菌群結構，但其中包含相同的優勢菌種。建立PCB脫氯菌群的16S rRNA clone library，發現不同的多氯聯苯的還原脫氯菌群皆分布在γ-和δ-Proteobacteria、low G+C gram-positive subgroup、Cytophagales和Spirochetes以及兩個未知的族群。比較不同脫氯途徑的菌群結構，結果顯示，間位與對位兩種不同脫氯解途徑的PCB同源物降解菌群在親源上的分布比例有所不同，對位脫氯菌群有二分之一分布在Low G+C phylum，其次為γ- Proteobacteria佔25%以下；反之，間位脫氯菌群則是有二分之一分布在γ- Proteobacteria，其次才是分布在Low G+C phylum，約佔12%。不含PCB的對照組菌群結構與PCB降解菌群有顯著差異，主要分布在β- Proteobacteria，佔全部的34.3%，且無γ- Proteobacteria分布。 Polychlorinated biphenyls (PCBs) is one of the most important environmental pollutants in last century. Microbial anaerobic degradation of PCBs in anaerobic environment is the most important step of degrading PCBs. However, the phylogenetic study of members degrading PCBs anaerobically is scarce and no pure culture has been obtained. In this study, we investigated microbial dechlorination of 2,4',5-CB, 2,2',5,5'-CB and 2,2',4,5,5'-CB by enriched anaerobic microbial consortia from sediment of Kee-Lung River. Several molecular-phylogenetic methods like clone library, DGGE, and FISH were used to study the microbial community degrading PCBs. 16S rRNA genes were amplified directly from aquifer material DNA by PCR with universal Eubacteria-specific primers and were cloned. The major groups of PCBs degraded consortia represented were the γ-andδ-Proteobacteria, low G+C gram-positive subgroup, Cytophagales, and Spirochetes. In addition, several clone groups unaffiliated with known bacterial assemblages were identified in the clone libraries. We discovered the degraded microorganism of three kinds of PCBs were different. The microbial diversity between tetra- and penta-chlorinated biphenyl degraded consortia were more similarity than trichlorinated biphenyl. |
