摘要
      好氧堆肥被认为是一种安全的污泥回收方式，提供了一个节约资源的绿色回收系统。污水处理厂的污泥已被确定为ARGs的重要蓄水池。然而，目前尚不清楚污泥中残留的抗生素是否会影响堆肥中细胞内和细胞外抗生素抗性基因（iARGs，eARGs）的水平转移机制。本文在磺胺甲恶唑（SMX）选择性压力污泥堆肥过程中提取了细胞内、细胞外和总基因组DNA。堆肥后，污泥中的大部分sul被去除，iARGs和eARGs的去除率分别在80%和90%左右。污泥中抗生素胁迫的存在将促进ARGs的水平转移。宏基因组测序证实，sul基因簇由多种可移动的遗传元件携带，如Tn3转座子和intl1，这促进了iARGs的水平转移。SMX选择性压力增加了负责SOS反应（29.52%）、IV型分泌系统（28.09%）和IV型菌毛（40.45%）的基因的表达。结合KEGG注释分析，SMX促进宿主（如假单胞菌）通过IV型菌毛摄入eARGs。总的来说，这是第一项验证iARGs和eARGs的水平转移是由堆肥过程中污泥中抗生素残留物的存在促进的研究。
Abstract
Aerobic composting has been considered a safe way to recycle sludge, providing a green recycling system that conserves resources. Sludge from sewage treatment plants has been identified as a significant reservoir for ARGs. However, it remains unclear whether the residual antibiotics in sludge affect the horizontal transfer mechanism of intracellular and extracellular antibiotic resistance genes (iARGs, eARGs) in compost. Here, intracellular, extracellular and total genomic DNA was extracted during sulfamethoxazole (SMX) selective pressure sludge composting. After composting, most of the sul in the sludge was removed, the removal rate of iARGs and eARGs was around 80 % and 90 %. The presence of antibiotic stress in sludge would promote the horizontal transfer of ARGs. Metagenomic sequencing confirmed that the sul gene cluster was carried by multiple mobile genetic elements, such as the Tn3 transposon and intl1, which promoted the horizontal transfer of iARGs. SMX selective pressure increased the expression of genes responsible for SOS response (29.52 %), type IV secretion systems (28.09 %) and type IV pili (40.45 %). Combined with the KEGG annotation analysis, SMX facilitated intake to eARGs by hosts, such as Pseudomonas, via type IV pili. Overall, this is the first study to verify that the horizontal transfer of iARGs and eARGs is promoted by the presence of antibiotic residues in sludge during composting.

https://www.sciencedirect.com/science/article/abs/pii/S1385894722054481