Distribution And Propagation Of Antibiotic Resistance Genes In The Coastal Sediment Of The East China Sea

Due to advanced economy development and serried population in the coastal area,coastal environment is greatly influenced by land-based pollution sources.To explore the pollution status and spread behavior of antibiotic resistance genes(ARGs)in the coastal sediment environment,this study chose the coast of the East China Sea as research area.Firstly,the study investigated the distribution pattern of ARGs in the sediments of Hangzhou Bay,Xiangshan Bay and Taizhou Bay,while explored the effects of class 1 integron(int I-1)and environmental factors on the distribution of ARGs.Then,the study focused on the inshore effluent receiving areas and offshore bay area of Hangzhou Bay,clearing the distribution pattern of ARGs and exploring the effect of WWTPs' effluent discharge on the distribution of ARGs in the coastal sediment.Lastly,the study analyzed the distribution rules of mobile genetic elements(MGEs),environmental factors and microbial community in the sediment of Hangzhou Bay,exploring the effects of MGEs,environmental factors and microbial community on the propagation of ARGs.The main results are as follows:(1)The abundance of ARGs in the sediment of Taizhou Bay was much higher than that of Hangzhou Bay and Xiangshan Bay.A total of 11 ARGs,including 6ARGs types and 5 resistance mechanisms were detected in all the bay sediments,mainly the sul I,tet W and dfr A13.Sulfanilamide and tetracycline resistance genes were the most abundant ARGs,while antibiotic target replacement and antibiotic target protection were the most general resistance mechanisms.int I-1,Hg,Cd and oil in the bay sediment correlated positively with multiple ARGs,the influences of metals and synergy of environmental factors on the distribution of ARGs were particularly important.(2)A total of 122 ARGs,including 9 ARGs types and 4 resistance machines were detected in the sediment of Hangzhou Bay,mianly the mex F,mph A-01,qac Edelta1-01 and so on.Multiple-drug resistance genes were the most widespread ARGs in the sediment of Hangzhou Bay,while antibiotic efflux pump was the most universal resistance mechanism.The diversity and abundance of ARGs in the inshore effluent receiving areas of Hangzhou Bay were much higher than that of offshore bay area,and there was significant difference of the distribution of ARGs and MGEs between the two areas.Specifically,the abundances of aminoglycoside,MLSB,multi-drug,sulfonamides,and vancomycin were the major ARGs types,which had significant differences between the inshore effluent receiving area and offshore bay area in the Hangzhou Bay;furthermore aac C,aad A2-03,mex F,ole C and sul2 were the significant differentiated ARGs subtypes.MGEs in the sediments were an important factor to affect the distribution of ARGs,especially tnp A-04,tnp A-05 and int I-1,which showed significant positive correlation with 53 ARGs subtypes.(3)In Hangzhou Bay,concentrations of the most environmental contaminants in the inshore effluent receiving area were higher than those in the offshore bay area.There was also significant difference of the sediment environmental factors between the two districts of Hangzhou Bay,Cr and Hg were the significant different environmental factors.In addition,environmental factors such as oil,Zn and Hg in the sediments were an important factor to affect the distribution of ARGs.(4)There was significant difference on the microbial communities between the inshore effluent receiving area and offshore bay area of Hangzhou Bay.A variety of genera,including some functional bacteria were strongly correlated with environmental factors,such as Cr and Hg.The relative abundance of these genera in the inshore effluent receiving area was significantly higher than that in the offshore bay area.Microbail community in the sediments was an important factor to affect the distribution of ARGs.There were 12 potential bacterial carriers of ARGs identified in the sediment of Hangzhou Bay,while multi-drug and ?-lactam ARGs were the most associated with bacterial genera.This study systematacially analyzes the distribution and spread of ARGs in the coast of the East China Sea,the research results strengthen the existing findings of ARGs in the polluted coastal environment,which also lays the ground for the future environmental risk assessment and control of ARGs in the environment.