Elimination Of Antibiotics And Antibiotics Resistance Genes In Sewage Treatment Plants And Preliminary Study On The Degradation Of Antibiotics By Microorganisms

Antibiotics are bioactive substances produced by microorganisms,plants and animals,as their secondary metabolites.The first antibiotic used in humans was penicillin,in world war II in 1940,as a specific medicine to treat bacterial infections.With the development of science and technology,people can use more and more kinds of antibiotics.The long use of antibiotics has brought us convenience and problems,such as antibiotic pollution,which has attracted extensive attention.Antibiotics contamination may has a number of consequences,most notably the induction of antibiotic-resistant bacteria.Human beings have many diseases caused by bacterial infections.Although antibiotics can kill bacteria,antibiotics abuse can cause antibiotics resistance in bacteria.And then,drug-resistant genes may be spread through the environment,making it easier to develop multidrug-resistant bacteria.There is an urgent need for people to find new antibiotics.The sewage plant is an important repository of antibiotics in the environment.This paper studies the Jinan Everbright Water(a plant)to explore the treatment effect of several major antibiotics and antibiotic resistance genes between each process.This work has positive significance for improving the wastewater treatment process of sewage treatment plants and improving the treatment capacity of antibiotics and antibiotic resistance genes.At the same time,this paper also makes a preliminary study on microbial degradation of antibiotics,and provides support for further study on the mechanism of microbial degradation of antibiotics.The wastewater treatment process of Everbright Water can be divided into five steps:water inlet,anaerobic treatment,aerobic treatment,silt precipitation and water discharge.With the intake,anaerobic pool,aerobic pool,second sink and outlet as the sampling points,the experimental materials were investigated with samples of sewage samples from each sampling point and the active sludge of the second sink.A total of 34 antibiotics resistant genes and integrase genes were tested.Results found seven commonly used antibiotics including beta lactam antibiotics,tetracycline antibiotics,quinolones,chloramphenicol antibiotics,aminoglycoside antibiotics,large ring lactone class antibiotics,sulfa antibiotics and related resistance genes,integrase genes can be detected at least one in five sampling points.The water intake has the most resistance genes and the water outlet has the least resistance genes.According to the result of the resistance gene detection,I selected the beta-lactam antibiotic resistance genes blaTEM,tetracycline antibiotic resistance genes tetW,quinolones resistance gene qnrS,chloramphenicol antibiotic resistance genes cmlA and floR,large ring lactone class antibiotic resistance genes ermB,sulfa antibiotic resistance genes sull,intll integrase gene and 16S rDNA and measured the abundance of the resistance genes.The ratio of copies of drug-resistant genes and copies of 16S rDNA represents the content of antibiotic resistance genes in the unit bacteria.It is used as the standard to measure the elimination of drug-resistant genes in sewage treatment system.Based on the results,the relative content of various resistant genes was basically unchanged after treatment,indicating that the wastewater treatment system could not remove the antibiotic resistance genes in the sewage.In this paper,the removal of cefalexin,sulfamethoxazole and erythromycin in the wastewater treatment process was analyzed by ultra performance liquid chromatography tandem mass spectrometry.According to the results,all four antibiotics have been detected,and the content is between 10 ng/L and 100 ng/L,indicating that antibiotics pollution in the domestic sewage is already very serious.After sewage treatment,the content of four kinds of antibiotics is reduced.The content of erythromycin was reduced by 87.5%.The content of cefalexin was reduced by 28%.The content of sulfamethoxazole and erythromycin has dropped below detection limit.It indicated that the treatment process of wastewater treatment plant can high efficiently eliminate the residue of antibiotics,but the specific mechanism needs to be further explored.A bacterium that can efficiently degrade cephalexin from chicken farm wastewater has been identified as Proteus mirabilis.Under the laboratory conditions for the degradation efficiency of cephalexin in 24h can reach 60%.Its degradation occurred in 12h.The bacteria can degrade cephalexin substances after experimental verification in bacterial cells.I conducted an experiment that explores the tolerance of bacteria with experimental drugs in 6 categories of 12 kinds of antibiotics.The result shows that the bacteria can resist 11 kinds of antibiotics,called multi-drug resistant bacteria.