Changes Of Antibiotic Resistance Genes In Lactose-Fermenting Enterobacteriaceae During Wastewater Treatment

Nowdays,antibiotic resistance genes(ARGs)have attracted wide attention as a new type of environmental pollutants.Although the changes of ARGs and ARB contained in wastewater treatment processes have been one of the research hotspots,there has been still a lack of understanding of the changes in ARGs contained in different microorganisms in the process,little changes of ARGs has been known in Enterobacteriaceae that are closely related to humans,especially.In this study,Lactose-Fermenting Enterobacteriaceae(LFE)and their ARGs in a municipal wastewater treatment plant and an antibiotic pharmaceutical plant were selected as main research subjects.With high-throughput sequencing technology and isolation and culture of traditional bacteria,a comprehensive analysis about the changes of the types and abundance of ARGs in 160 strains of LFEs and tetracycline resistant Lactose-Fermenting Enterobacteriaceae(TR-LFE)in influent,activated sludge and effluent water samples,focusing on analyzing tetracycline resistance types and abundance changes.Get the following conclusions:1.The quantity of LFE and TR-LFE in the effluent water samples of the two sewage treatment plants was reduced by 1 to 3 orders of magnitude compared with the influent water samples,and the reduction effect was obvious.However,the proportion of resistant bacteria increased,the ratio of TR-LFE to LFE in the municipal sewage treatment plant increased from 10% to 33%,and the ratio of TR-LFE to LFE in wastewater treatment stations of antibiotic pharmaceutical plant was increasing from 3 % to 12%.2.From municipal sewage treatment plant,17 types of ARGs and 14 kinds of tetracycline resistance genes were detected in LFEs(480 total)screened and isolated from water samples.TR-LFE(480 total)obtained with the same way had 17 types of ARGs and 15 kinds of tetracycline resistance genes.20 types of ARGs and 31 kinds of tetracycline resistance genes were detected from three water samples: influent,activated sludge and effluent.After treatment,the total abundance of ARGs in water samples,LFE and TR-LFE isolated from them had reduced by 9% to 44%.3.From wastewater treatment station of antibiotic pharmaceutical factory,17 types of ARGs and 11 kinds of tetracycline resistance genes were detected in the LFE(a total of 480 strains)isolated and screened from the station.From three water samples,influent,activated sludge and effluent,17 types of ARGs and 28 kinds of tetracycline resistance genes were detected.After treatment,the total abundance of ARGs in the water samples and LFE isolated from them had reduced by 21% to 72%.4.Through comparative analysis,it was found that the type of ARGs in the municipal sewage treatment plant was more than that in the antibiotics factory wastewater treatment station,but the abundance of ARGs was lower than that in antibiotics pharmaceutical wastewater treatment station.Drug-resistant bacteria and antibiotic resistance genes existed in the effluent water samples of the two sewage plants.It can be seen that the sewage treatment plant is one of the sources of contamination of drug-resistant bacteria and resistance genes.