摘要
      目前，对无抗生素水产养殖的需求有所增加，但在没有抗生素添加剂的情况下，AMR在水产养殖中的传播范围还有待阐明。因此，我们旨在揭示在无抗生素水产养殖系统中影响AMR的潜在因素。作为一个模型系统，我们使用了含有非洲鲶鱼（Clarias gariepinus）的封闭循环水产养殖。我们在不同的饲养期对水和生物膜进行了采样，并对六个抗生素抗性基因（ARGs）、1类整合子整合酶基因intI1和16S rRNA基因进行了16S核糖体RNA（rRNA）高通量测序和qPCR。同时，我们监测了水产养殖应用期间的物理化学水参数。在饲养过程中，氮化合物积累到42.00±18.17mg/L的铵、153.0±7.5mg/L的硝酸盐和2.9±0.9mg/L的亚硝酸盐。然而，这并没有影响生物膜或水生样品中的优势细菌群落或ARG丰度。尽管没有使用抗生素，但在饲养过程中，ARGs始终以高相对丰度出现，但水平不变（例如sul1:−2.0±1.5 log10拷贝/16S rRNA）。此外，一种ARG，即β-内酰胺酶基因blaTEM与细菌生物膜的生活方式显著相关。其丰度进一步与微生物群落的分类组成和α-多样性相关。总之，ARGs以较高的相对丰度存在，但在循环水产养殖期间保持稳定。因此，尽管没有选择性压力，但细菌群落在水产养殖过程中仍能保持高ARG丰度。
Abstract
Currently the demand for antibiotic free aquaculture has increased, but to which extend AMR spreads in aquaculture in the absence of antibiotic additives remains to be elucidated. Therefore, we aimed to reveal potential factors that affect AMR in antibiotic free aquaculture systems. As a model system, we utilized enclosed recirculating aquaculture containing African catfish (Clarias gariepinus). We sampled water and biofilms during various rearing periods and performed 16S ribosomal RNA (rRNA) high-throughput sequencing and qPCR for six antibiotic resistance genes (ARGs), the class 1 integron integrase gene intI1 and the 16S rRNA gene. In parallel, we monitored the physicochemical water parameters during the duration of aquaculture application. During the rearing operation nitrogen compounds accumulated to 42.00 ± 18.17 mg/L ammonium, 153.0 ± 7.5 mg/L nitrate and 2.9 ± 0.9 mg/L nitrite. However, this did not influence the dominant bacterial communities or ARG abundance in either biofilm or aquatic samples. Despite the absence of antibiotic use, ARGs consistently occurred in high relative abundance, but at constant levels (e.g. sul1: −2.0 ± 1.5 log10 copies/16S rRNA) during rearing. Moreover, one ARG, the β-lactamase gene blaTEM was significantly associated with the bacterial biofilm lifestyle. Its abundance further correlated with the taxonomic composition and α-diversity of the microbial communities. In conclusion, ARGs, were present in high relative abundance, but remained stable during the period of recirculating aquaculture. Consequently, bacterial communities were able to retain high ARG abundance during aquaculture operations, despite the absence of selective pressures.

https://www.sciencedirect.com/science/article/pii/S2772416622001577