摘要
      细胞内和细胞外抗生素抗性基因（iARGs和eARGs）共同构成污泥中的抗性组。然而，iARGs和eARGs在污泥厌氧消化（AD）和预处理过程中的各自命运尚不清楚。本研究首先比较了碱预处理（ALP）、热预处理（THP）和酶促预处理（ENP）三种预处理方法对污泥中iARGs和eARGs的去除效果。然后研究了iARGs和eARGs在随后的30天批量AD中的变化和机制。采用定量PCR测定7种ARG（tet（A）、tet（O）、tet（X）、sul1、sul2、blaSHV和blaTEM）的细胞内和细胞外绝对丰度。THP对iARGs和eARGs的去除效果最强（1.3–5.1 log），其次是ALP（0.3–1.0 log），而ENP对它们的去除影响较小（蛋白酶预处理0.05 log）。在随后的AD中，iARGs和eARGs的绝对丰度在伴有THP的AD期间回升。在有ALP和ENP和无预处理的AD期间，细胞内tet（O）的丰度增加，而其他iARG和所有eARG的绝对丰度降低。eARGs的去除量高于iARGs。从整个预处理AD过程的角度来看，与未经预处理的AD相比，在去除iARGs和eARGs方面没有观察到任何优势。冗余分析和偏最小二乘路径建模结果表明，细菌群落组成直接影响iARGs的变化。iARGs和污泥理化性质的变化共同直接影响eARGs的变化。
Abstract
Intracellular and extracellular antibiotic resistance genes (iARGs and eARGs) together constitute the resistome in sludge. However, the respective fates of iARGs and eARGs during sludge anaerobic digestion (AD) with pretreatments are unclear. In this study, the removal effects of three kinds of pretreatment methods including alkaline pretreatments (ALP), thermal pretreatments (THP), and enzymatic pretreatments (ENP) on iARGs and eARGs removal in sludge were first compared. Then the variations and mechanisms of iARGs and eARGs during the subsequent 30-day batch AD were investigated. Quantification PCR was adopted to determine the intracellular and extracellular absolute abundances of seven ARGs (tet(A), tet(O), tet(X), sul1, sul2, blaSHV, and blaTEM). THP showed the most potent removal effects for iARGs and eARGs (1.3–5.1 log), followed by ALP (0.3–1.0 log), while ENP had a minor impact on their removal (0.05 log by protease pretreatment). In the subsequent AD, the absolute abundances of iARGs and eARGs rebounded during AD with THP. Intracellular tet(O) increased its abundances while the absolute abundances of other iARGs and all eARGs decreased during AD with ALP and ENP and without pretreatments. The removal amounts of eARGs were higher than those of iARGs. From the perspective of the whole pretreatment-AD process, no advantages were observed in the removal of both iARGs and eARGs than AD without pretreatments. Redundancy analysis and partial least squares path modelling results revealed that bacterial community composition directly influenced the iARGs variations. The variations in iARGs and sludge physicochemical properties together directly influenced the eARGs variations.

https://www.sciencedirect.com/science/article/abs/pii/S1385894722058363