| The reuse of reclaimed water will introduce trace toxic and harmful substances,which will lead to hidden dangers in the water environment,thus causing potential hazards to human health.According to long-term contaminated site investigation,this study selected sulfamethoxazole?SMX?as the primary control of pollutants,the concentration gradient of the common metabolic domesticated separation and screening of sulfamethoxazole degradation ability of the strains,using ultra high performance liquid chromatograph to determine the degradation ability of degrading bacteria and degradation was studied in the laboratory strain 2-T on the biodegradability of SMX,to clarify the optimal degradation conditions,the specific research results are as follows:?1?Monitoring and analysis of the 21 antibiotic contamination levels investigated in the polluted site sewage,and found that the highest concentration was SMX.The concentration of SMX in water is as high as 542.47 ng/L.According to the results of environmental ecological risk assessment,it shows that SMX is a high-risk substance in water.Therefore,SMX is the target pollutant for priority control.The 16S rDNA molecular sequencing method was used to determine the microbial community structure in the water environment.From the sequencing results,the microbial community structure diversity in the water environment was good,and there were obvious dominant genus.Thirty dominant genus were detected at the genus level,and there were 9dominant genus with an average abundance level greater than 1%,namely Pseudomonas?27.6%?and Opitutus?18.3%?,Methylotenera?9.3%?,Smithella?5.9%?,Simplicispira?5.5%?,Methyloversatilis?1.6%?,Arenimonas?1.6%?and Pseudoxanthomonas?1.3%?.?3?Seven strains isolated from the degrading microbial MX-3 without the addition of a co-metabolizing carbon source were able to synthesize biomass using SMX as a carbon source.The SMX was used as the sole carbon source to compare the ability of 7strains to degrade SMX.The results showed that 7 strains of single bacteria could survive with SMX as the sole carbon source,and all of them had certain degradation effects.The degradation effects of 2 and 2-T were better,and the degradation rates were62%and 69%,respectively.According to the first-order kinetics fitting of the 7 strains of degradation test data,strain 2-T with high-efficiency degradation ability was taken as an experimental strain according to the ratio constant and half-life comprehensive consideration in the fitting results.According to its morphological characteristics,physiological and biochemical characteristics observation and 16S rDNA gene sequence phylogenetic analysis,the strain was identified as Pseudoochrobactrum sp.?4?The optimal removal conditions for high-efficiency degradation bacteria 2-T are:;?1?lower initial concentration of SMX,the degradation effect of strain 2-T was good..;?2?high inoculation amount of bacterial suspension promoted the degradation of SMX by strain 2-T;?3?pH=7.0;?4?temperature is 25?;?5?the removal process of SMX by 2-T was consistent with the first order kinetic equation;?6?Ea=44.89 kJ/mol in the SMX degradation reaction of strain 2-T,which was a highly efficient degradation bacterium,indicating that the degradation of SMX by 2-T was easy to occur;?7?the degradation process of SMX by bacteria 2-t was consistent with Monod kinetics,the maximum specific degradation rate?max=0.285 min-1,and the partial saturation constant Ks=63.364 mg·L-1,which could be used as a highly efficient degradation bacteria with sulfamethoxazole as a single carbon source. |
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