Investigation On The Main Antibiotic Residues And The Abundance Of Drug Resistance Genes In The Ecological Environment Of Jiangsu Coastal Aquaculture

The purpose of this study was to analyze the diversity and distribution characteristics of antibiotic distribution,drug resistance gene level,and microbial community structure in key areas of mariculture in Jiangsu coastal area.The concentration levels of 14 antibiotics in three major categories in water samples were studied by high-performance liquid chromatography tandem mass spectrometry,and their ecological risks were evaluated using risk quotient method.Four cultivation modes were selected,namely,the warming shed culture of Litopenaeus vannamei(LV),the mixed culture of Exopalaemon carinicauda and Portunus trituberculatus(EP),the mixed culture of Penaeus japonicus and Portunus trituberculatus(PP),and the pond culture of Fenneropenaeus chinensis and Sinonovacula constricta(FS).Macrogenomic sequencing was used to explain the abundance and diversity of antibiotic resistance genes in microorganisms,as well as the distribution characteristics of movable genetic elements,The diversity and structure of microbial communities in the aquaculture environment were analyzed using 16 S r RNA amplification sequencing.The main results are as follows:1.The overall detection rate of 14 antibiotic residues in three major categories of water samples from key areas of seawater ponds in three coastal cities in Jiangsu Province is not high,with over half of the antibiotics not detected(ND).The antibiotic pollution and ecological risk quotient values of each sampling point in the mariculture area of the coastal area of Jiangsu Province are very low,with the lowest antibiotic risk quotient value(0<RQ<0.01)for aquaculture pond water,and the highest risk quotient value for estuaries.2.The abundance and diversity of microorganisms in the culture mode decreased in turn in the warming shed culture of LV,the pond culture of FS,the mixed culture of PP,and the mixed culture of EP.Bacteroides is the most abundant in the warm water culture of LV,while Proteobacteria is the most abundant in the mixed culture of PP and FS,while Actinomyces are the main species in the mixed culture of EP.After macrogenomic analysis,the abundance of various antibiotic resistance genes in the four groups of samples is very low,but multiple antibiotic resistance genes such as tetracyclines,fluoroquinolones,and macrolides have already existed in water samples.3.The analysis of water samples using macro genomic high throughput sequencing technology showed that the abundance of various drug resistance genes was relatively low,mainly including tetracyclines,fluoroquinolones,sulfonamides,and macrolides.Drug resistant genes can be transferred horizontally between bacteria through mobile elements,and the frequency of transfer is higher than other genes.This study also found that the relative abundance of drug resistant genes is also higher in mobile element samples with higher relative abundance,which may be one of the reasons for the widespread spread of drug resistant genes in the aquaculture environment.