high-risk antibiotic resistance genes and pathogens in different water types
Animal carcass decay produced many poisonous metabolites and chemical pollutants, which pose potential ecological risks to the water environment and human health. However, the effects of animal cadaver decomposition on high-risk antibiotic resistance genes (ARGs) and potential pathogens in different water types are still unknown. In this study, fifteen freshwater economic fish (Carassius auratus) corpses were put into three types of water (i.e., pond water, tap water, and domestic sewage) for a 100-days decomposition. 16S rRNA gene sequencing and high-throughput quantitative PCR were used to illustrate how corpse decomposition affects microbial communities and ARG profiles. Our results revealed that the relative abundance of the potential pathogen Bacteroidetes was more than 37 times in carcass groups than that in control groups. For the ARG profiles, ß-lactamase, MLSB (Macrolide-Lincosamide-Streptogramin B), Sulfonamide, tetracycline resistance genes and transposase genes in the experimental groups were increased. Among them, tetracycline resistance genes were enriched 224 to 136,218-fold during the process of corpse degradation. Furthermore, high-risk ARGs (ermB, floR and dfrA1), which resist to MLSB, multidrug and sulfonamide respectively, were significantly enriched in the cadaver groups and had co-occurrence patterns with opportunistic pathogens. The study was able to draw a general conclusion that cadaver decomposition of freshwater economic fish deteriorates the aquatic environment by affecting high-risk ARGs and pathogenic microorganisms, which pose potential threats to human health.