The Production And Variation Of Tetracycline Resistance Gene In Biological Wastewater Treatment System

At present, an increasing number of antibiotics is used into the medical treatmentindustry around the world. The massive antibiotics were produced and used with thelack of effective management, making abuse of the medical antibioticsextremely serious, even the post-antibiotic effect appears. Antibiotics and resistancegenes come into the sewage system along with medical wastewater, pharmaceuticalwastewater and aquaculture wastewater, however the existing water treatmenttechnologies have no effect on most antibiotic material or resistance genes. Therefore itis significant and urgent to carry on the study of the production and variation ofresistance gene in wastewater treatment system.Tetracycline is a typical broad-spectrum antibiotics. The study discussed in thispaper adopted MBR and SBR to process the tetracycline pharmaceutical wastewaterwhich is refractory and at high concentration. Firstly, tetracycline was selected as thetarget pollutant and glucose as co-metabolism substrate in study. The treatment effectfor the simulating of tetracycline was studied under different load conditions in MBRand SBR. Four kinds of tetracycline resistance genes were selected and analyzed byPCR and quantitative real-time PCR. Finally, The production and distribution oftetracycline resistance gene were investigated by use of the actual pharmaceuticalwastewater in hydrolysis acidification aerobic treatment process.The results of experiment showed that the tetracycline resistance gene turned upin the MBR and SBR process, and the detection rate of tetracycline resistance gene reached more than86.13%. In Experiment, the change of load and concentration oftetracycline was divided into three stages in influent. The removal efficiency of CODwas more than80%, the removal efficiency of tetracycline was more than74%, and theremoval efficiency of NH4+-N was more than89％in every stage. The change of thetetracycline resistance gene has a certain relevance with the changes of COD andNH4+-N. In MBR and SBR reactor, the tetracycline resistance genes of tet(A)、tet(C)、tet(M) and tet(X) were removed to some extent, and the relative gene copy numberdecreased2to3orders of magnitude in effluent. The relative gene copy number ofresistance gene in the sludge was higher1to2orders of magnitude than that in theeffluent.The removal efficiency of COD was more than78.2%, and that of the NH4+-Nwas up to99.3％in Hydrolysis acidification-oxidation process adopted bypharmaceutical wastewater treatment process. The comparison results of the four kindsof resistant genes showed that there is the most abundance in the tet(A) and tet(C),followed by enzymatic modification class resistant gene tet(X). The resistant genecontent of sewage is higher than that of the sludge, and the abundance of the tet(A) andtet(C) is the highest.