Thermal hydrolysis pretreatment (THP) can effectively remove the antibiotic resistance genes (ARGs) from sewage sludge, but the rebounding effects in the subsequent anaerobic fermentation are often observed. The purpose of this study was to elucidate the distribution and fate of intracellular and extracellular ARGs (iARGs and eARGs) in the sludge acidogenic fermentation process coupled with THP. Our results revealed that THP significantly reduced the absolute abundance of total ARGs in raw sludge but increased eARGs by 0.3–1.4 log units under practical conditions (140 °C for 30 min). There is no significant difference in the removal of total ARGs between the two acidogenic fermenters receiving raw and hydrolyzed sludge, with iARGs prevailing in the produced biosolids. The succession of bacterial community and the co-occurrence relationships among ARG type, mobile genetic elements and bacterial taxa were observed, suggesting a phylogenetic basis for the iARGs patterns in fermented sludge. However, eARGs were susceptible to biodegradation with a half-life of 2.34 h and they contributed limitedly to the ARGs propagation through transformation. These findings suggest an emphasis on the mitigation of iARGs during the acidogenic fermentation of sludge, which would be achieved by lowering the richness and physicochemical destruction of potential hosts.

热水解预处理（THP）可以有效去除污水污泥中的抗生素抗性基因（ARG），但在后续的厌氧发酵中经常会出现反弹效应。本研究的目的是阐明细胞内和细胞外 ARG（iARG 和 eARG）在与 THP 结合的污泥产酸发酵过程中的分布和命运。我们的结果表明，在实际条件下（140℃，30分钟），THP显着降低了原污泥中总ARG的绝对丰度，但使eARG增加了0.3-1.4个对数单位。接收原始污泥和水解污泥的两个产酸发酵罐之间的总 ARG 去除率没有显着差异，iARG 在产生的生物固体中占主导地位。观察到细菌群落的演替以及ARG类型、移动遗传元件和细菌类群之间的共现关系，提示发酵污泥中iARGs模式的系统发育基础。然而，eARG 易于生物降解，半衰期为 2.34 小时，并且它们通过转化对 ARG 传播的贡献有限。这些发现表明，应强调在污泥产酸发酵过程中减轻 iARG，这可以通过降低潜在宿主的丰富度和物理化学破坏来实现。