Data from: Aquatic animals promote antibiotic resistance gene dissemination in water via conjugation: role of different regions within the zebra fish intestinal tract, and impact on fish intestinal microbiota

The aqueous environment is one of many reservoirs of antibiotic resistance genes (ARGs). Fish, as important aquatic animals which possess ideal intestinal niches for bacteria to grow and multiply, may ingest antibiotic resistance bacteria from aqueous environment. The fish gut would be a suitable environment for conjugal gene transfer including those encoding antibiotic resistance. However, little is known in relation to the impact of ingested ARGs or antibiotic resistance bacteria (ARB) on gut microbiota. Here, we applied the cultivation method, qPCR, nuclear molecular genetic marker and 16S rDNA amplicon sequencing technologies to develop a plasmid-mediated ARG transfer model of zebrafish. Furthermore, we aimed to investigate the dissemination of ARGs in microbial communities of zebrafish guts after donors carrying self-transferring plasmids that encode ARGs were introduced in aquaria. On average, 15% of faecal bacteria obtained ARGs through RP4-mediated conjugal transfer. The hindgut was the most important intestinal region supporting ARG dissemination, with concentrations of donor and transconjugant cells almost 25 times higher than those of other intestinal segments. Furthermore, in the hindgut where conjugal transfer occurred most actively, there was remarkable upregulation of the mRNA expression of the RP4 plasmid regulatory genes, trbBp and trfAp. Exogenous bacteria seem to alter bacterial communities by increasing Escherichia and Bacteroides species, while decreasing Aeromonas compared with control groups. We identified the composition of transconjugants and abundance of both cultivable and uncultivable bacteria (the latter accounted for 90.4%–97.2% of total transconjugants). Our study suggests that aquatic animal guts contribute to the spread of ARGs in water environments.水生环境是抗生素耐药基因（antibiotic resistance genes, ARGs）的众多储存库之一。鱼类作为重要的水生动物，拥有适于细菌生长繁殖的理想肠道微生境，可从水生环境中摄入耐药菌（antibiotic resistance bacteria, ARB）。鱼类肠道是接合型基因转移的适宜环境，此类转移可发生在编码抗生素耐药基因的遗传物质之间。然而，目前关于摄入的抗生素耐药基因或耐药菌对肠道微生物群的影响，相关研究仍较为匮乏。本研究采用培养法、实时定量PCR（qPCR）、核分子遗传标记及16S rDNA扩增子测序技术，构建了斑马鱼的质粒介导型抗生素耐药基因转移模型。此外，本研究旨在探究当向水族箱中引入携带编码抗生素耐药基因的自主转移性质粒的供体菌后，斑马鱼肠道微生物群落中抗生素耐药基因的传播扩散情况。平均有15%的粪便细菌通过RP4质粒介导的接合转移获得了抗生素耐药基因。后肠是支持抗生素耐药基因传播的最关键肠道区域，供体菌与接合子的细胞浓度几乎是其他肠段的25倍。此外，在接合转移最为活跃的后肠中，RP4质粒的调控基因trbBp与trfAp的mRNA表达水平显著上调。与对照组相比，外源菌似乎通过增加埃希氏菌属（Escherichia）和拟杆菌属（Bacteroides）的物种丰度、降低气单胞菌属（Aeromonas）的丰度来改变肠道细菌群落结构。本研究明确了接合子的群落组成，以及可培养与不可培养细菌的丰度特征，其中不可培养细菌占总接合子的90.4%~97.2%。本研究结果表明，水生动物肠道会促进抗生素耐药基因在水环境中的传播扩散。