Diverse and abundant antibiotic resistance genes from mariculture sites of China's coastline

With the rapid development of mariculture in China, large amounts of antibiotics are being discharged into the aquatic environment. Little information is available regarding antibiotics and corresponding antibiotic resistance genes (ARGs) associated with maricultural environments in China. Sediments from eleven typical mariculture areas along the whole coastline of China were collected, and the sediment in Meijijiao in southern China was used as a non-mariculture control. The results revealed that antibiotics and their corresponding ARGs were widely distributed in most maricultural sediments, and present at low concentrations in samples from Meijijiao. The sulfonamide-resistance genes were prevalent, and the sul1 and sul2 in Penglai were the highest detected by using quantitative PCR. Moreover, remarkable differences in ARGs among different sites were observed. Due to the limited availability of primers to detect ARGs, illumina high-throughput sequencing was also used for profiling ARGs, and the results showed that the abundance of bacA in all samples was the highest compared to other ARGs, followed by mexF and mexB. This is the first study to comprehensively investigate the antibiotic resistance profile in typical mariculture areas along the whole coast of China. This study provides insights into the impacts of mariculture on the profiles of bacterial and ARG compositions in China. (C) 2018 Published by Elsevier B.V.