| Objective:To study the degradation effect and molecular mechanism of bacteria on dexamethasone steroid hormones,and 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-degrading bacterium was isolated from hospital wastewater.The degradation rates of dexamethasone were determined by using high performance liquid chromatography(HPLC)method.The dexamethasone-degrading bacterium was identified with 16 S 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 RT-q PCR.Results:A strain of bacteria with higher degradation to dexametha sone were isolated and identified as Burkholderia,named Burkholderia sp.CQ001.The degradation rates of dexamethasone sodium phosphate and dexamethasone were 84.8% and 77.11% respectively.Genome sequ encing results demonstrated that the bacteria contains 2 chromosomes a nd 4 giant plasmids.Bioinformatic analysis results showed that Burkhold eria sp.CQ001 has some significant genes that encode enzymes working in the dexamethasone degradation pathway,such as ABC transporter,3-ketosteroid-9-alpha-monooxygenase,etc.The expression levels of these genes were higher when Burkholderia sp.CQ001 was grown in a medi um 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 kind of bacteria with strong metabolic function and metabolic pathway.It has the properties of degrading dexamethasone steroid hormones.Our findings may provide new strain and more evidence for the further studies concerning dexamethasone degradation mechanisms and establishment of bioremediation engineering bacteria for eliminating dexamethasone pollution. |
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