摘要
      抗生素抗性基因（ARGs）的形成和传播越来越受到人们的关注。目前尚不清楚抗生素在厌氧消化（AD）过程中影响ARGs水平基因转移（HGT）的内在机制是否受到剂量和类型的影响。我们根据牲畜废水中的抗生素浓度，研究了两种主要抗生素（土霉素、OTC和磺胺甲恶唑、SMX）对AD期间ARGs的影响。低剂量抗生素（0.5 mg/L）增加了ROS和SOS反应，促进了ARGs的形成。同时，低剂量抗生素也可以通过促进菌毛、交流反应和IV型分泌系统（T4SS）来促进ARGs的传播。然而，不同类型和剂量的抗生素会导致上述功能模块发生变化，进而影响ARGs的富集。随着SMX剂量的增加，菌毛和交流反应的优势将逐渐改变。在OTC系统中，低剂量对菌毛和交流反应的促进能力最强。类似地，SMX剂量的增加将使T4SS从促进变为抑制，而OTC则完全抑制T4SS。微生物和网络分析还表明，低剂量抗生素更有利于宿主细菌的生长。
Abstract
The formation and transmission of antibiotic resistance genes (ARGs) have attracted increasing attention. It is unclear whether the internal mechanisms by which antibiotics affect horizontal gene transfer (HGT) of ARGs during anaerobic digestion (AD) were influenced by dose and type. We investigated the effects of two major antibiotics (oxytetracycline, OTC, and sulfamethoxazole, SMX) on ARGs during AD according to antibiotic concentration in livestock wastewater influent. The low-dose antibiotic (0.5 mg/L) increased ROS and SOS responses, promoting the formation of ARGs. Meanwhile, low-dose antibiotics could also promote the spread of ARGs by promoting pili, communication responses, and the type IV secretion system (T4SS). However, different types and doses of antibiotics would lead to changes in the above functional modules and then affect the enrichment of ARGs. With the increasing dose of SMX, the advantages of pili and communication responses would gradually change. In the OTC system, low-dose has the strongest promoting ability in both pili and communication responses. Similarly, an increase in the dose of SMX would change T4SS from facilitation to inhibition, while OTC completely inhibits T4SS. Microbial and network analysis also revealed that low-dose antibiotics were more favorable for the growth of host bacteria.

https://www.sciencedirect.com/science/article/abs/pii/S0304389422016636