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Abstract：
Dioxin compounds are persistent carcinogenic byproducts of anthropogenic activities such as waste combustion and other industrial activities. The ubiquitous distribution of dioxins is global concerns these days. Among of recent techniques, bioremediation, an eco-friendly and cost-effective technology, uses bacteria or fungi to detoxify in dioxins; however, not many bacteria can degrade the most toxic dioxin congener 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD). In this study, the endophytic bacterium Burkholderia cenocapacia 869T2 was capable of TCDD degradation by nearly 95 % after one-week of an aerobic incubation. Through transcriptomic analysis of the strain 869T2 at 6 -h and 12 -h TCDD exposure, a number of catabolic genes involved in dioxin metabolism were detected with high gene expressions in the presence of TCDD. The transcriptome data also indicated that B. cenocepacia strain 869T2 metabolized the dioxin compounds from an early phase (at 6 h) of the incubation, and the initial outline for a general dioxin degradation pathway were proposed. One of the catabolic genes, l-2-haloacid dehalogenase (2-HAD) was cloned to investigate its contribution in dioxin dehalogenation. By detecting the increasing concentration of chloride ions released from TCDD, our results indicated that the dehalogenase played a crucial role in dehalogenation of dioxin in the aerobic condition.
摘要：
二恶英化合物是人为活动如废物燃烧和其他工业活动的持久性致癌副产物。如今，二恶英的普遍分布是全球关注的问题。在最近的技术中，生物修复，一种环保且具有成本效益的技术，使用细菌或真菌解毒二恶英;然而，没有多少细菌可以降解毒性最强的二恶英同源物2,3,7,8-四氯化二苯并-对二恶英（TCDD）。在这项研究中,内生细菌伯克霍尔德氏菌869T2在有氧孵育一周后能够将TCDD降解近95％。通过对菌株869T2在6-h和12-hTCDD暴露的转录组学分析，在存在TCDD的情况下，检测到许多参与二恶英代谢的分解代谢基因具有高基因表达。转录组数据还表明，在孵育的早期阶段（在6小时），并提出了一般二恶英降解途径的初步轮廓。分解代谢基因之一，克隆了1-2-卤酸脱卤酶（2-HAD），以研究其在二恶英脱卤中的作用。通过检测从TCDD释放的氯离子浓度的增加，我们的研究结果表明，脱卤酶在好氧条件下二恶英的脱卤中起着至关重要的作用。
