Isolation,Classification And Degradation Characteristic Of Sulfamethoxazole Degrading Bacteria

The amount of aquaculture in China ranks first in the world all the year round.The huge output mainly depends on intensive and high-density aquaculture,which increases the risk of aquatic animal diseases.Sulfamethoxazole is one of the most commonly used broad-spectrum antimicrobial agents to treat a series of bacterial diseases in aquatic animals.However,with the extensive use of the drug,the food safety hazards caused by its residues are becoming more and more serious.Therefore,it is of great value to study and solve the frequent sulfonamides residues in current aquaculture production to ensure the quality and safety of aquatic products and the green and sustainable development of China's fishery.Existing research results show that microbial degradation is an effective means to remove sulfamethoxazole residues.In this study,with the antibacterial drug sulfamethoxazole as the only carbon source,high efficiency sulfamethoxazole-degrading bacteria were obtained through four successive passage enrichment,and the following research results were obtained.1.The community composition and abundance of each generation of degrading bacteria were analyzed by high-throughput sequencing,and the bacterial strains related to the degradation of sulfamethoxazole were speculated.It was found that strain Sphingobacterium might play an important role in the degradation of sulfamethoxazole.2.Five strains of sulfamethoxazole-degrading bacteria were isolated and purified from the fourth generation of degrading bacteria group SMX4 by different medium.One of the most effective degradation strains LLE3 was studied in depth.Based on 16S r RNA and physiological and biochemical identification,LLE3 was identified as Sphingobacterium mizutaii.3.The whole genome of strain LLE3 was sequenced and bioinformatics analysis was performed.The LLE3 gene was annotated by GO,KEGG and other databases,and 12 genes that may be related to sulfamethoxazole degradation were found.4.The optimal degradation condition is 29.5?,p H 6.8,inoculation concentration of5.4×10~7 cfu/m L of the strain LLE3 were determined by response surface methodology.Under these conditions,the degradation efficiency of the strain LLE3 to 50 mg/L sulfamethoxazole could reach 93.7%within 7 days.5.The strain LLE3 after degradation was identified as N-[4-(1,2-oxazol-3-yl sulfamoyl)phenyl]acetamide by high performance liquid chromatography and mass spectrometry.These results provide excellent microbial resources for remediation of sulfamethoxazole-polluted water and soil environment at the same time.