中文摘要：

目的研究细菌对地塞米松类甾体激素的降解作用及其分子机制,为构建清除水环境医源性地塞米松类药物污染的工程菌奠定基础。方法采用富集培养法从医院废水中分离降解地塞米松的细菌,采用固相萃取-高效液相色谱（HPLC）法检测细菌对地塞米松的降解效能,通过16S r DNA序列测定进行鉴定。用Illumina Hiseq4000结合第三代测序技术对降解菌的全基因组测序,并进行序列组装、注释和分析,对降解地塞米松相关基因进行RT-q PCR验证。结果分离到1株对地塞米松有较高降解作用的细菌,经鉴定属于伯克霍尔德菌属（Burkholderia）,命名为Burkholderia sp.CQ001。该菌对地塞米松磷酸钠及地塞米松的降解率分别为84.8%和77.11%。全基因组测序表明Burkholderia sp.CQ001包含2条染色体和4个巨型质粒,与代谢相关基因大部分集中在2号染色体上,共3 260 157 bp。生物信息学分析表明,该菌含有甾体代谢通路中许多重要酶类的编码基因,其中与地塞米松降解相关的有ABC转运子,3-甾酮-9α-脱氢酶等,这些基因在以地塞米松磷酸钠为碳源的培养条件下表达量不同程度地高于以蔗糖为碳源的培养条件。结论 Burkholderia sp.CQ001是一株具有强大的代谢功能和代谢途径丰富的细菌,具有降解地塞米松类甾体激素的性能,该菌株为后续研究甾体激素的降解机制和构建清除水环境医源性地塞米松类药物污染的工程菌提供了菌种。

英文摘要：

Objective To investigate the degradation effect and molecular mechanism of bacteria on dexamethasone steroid hormones, in order to lay the foundation for the construction of engineering bacteria to eliminate the pollution of iatrogenic dexamethasone drugs in water environment. Methods By enrichment culture method, dexamethasone degradation bacteria were isolated from hospital waste water. The degradation rates of dexamethasone were determined by using high performance liquid chromatography （HPLC）. The dexamethasone degradation bacterium was identified with 16S rDNA sequencing. The whole genome sequencing was performed using Illumina Hiseq4000 combined with third generation sequencing technology, and sequence assembly, annotation and analysis. Some degradation of dexamethasone related genes were further verified by real time RT-qPCR. Results A strain of bacteria with higher degradation to dexamethasone were isolated, and then identified as Burkholderia, which was named Burkholderia sp. CQ001. The degradation rates were 84.8% to dexamethasone sodium phosphate and 77. 11% to dexamethasone. Genome sequencing results demonstrated that the bacterium contained 2 chromosomes and 4 giant plasmids.Most of the metabolic retated genes were concentrated in chromosome 2, accounting for 3 260 157 bp. Bioinformatic analysis results showed that Burkholderia sp. CQ001 had some significant genes that encoded enzymes working in the steroid degradation pathways, including asABC transporter, 3-ketosteroid-9alpha- monooxygenase,etc, which are involved in the dexamethasone degradation. The expression levels of these genes were higher when Burkholderia sp. CQ001was grown in a medium with dexamethasone sodium phosphate as the unique carbon source than in a medium with glucose as the unique carbon source. Conclusion Burkholderia sp. CQ001 is a strain of bacterium with strong metabolic function and metabolic pathway. It has the properties of degrading dexamethasone steroid hormones. Our findings may provide new strain and much evidence