摘要

      蚯蚓堆肥能显著降低剩余活性污泥中的抗生素抗性基因（ARGs）。然而，蚯蚓的作用，特别是作为蚯蚓堆肥过程中一个关键步骤的肠道消化作用，仍未得到证实。本研究旨在通过定量聚合酶链式反应（q-PCR）和高通量测序，从细菌群落的角度，研究EAS中的ARGs（无细胞和相关）对蚯蚓肠道消化的反应，并阐明其可能的机制。与初始污泥相比，蚯蚓粪中ARGs的绝对丰度明显降低，尤其是qnrS、tetM和tetX的去除率均超过90%。无细胞和相关的ARGs（sul1和tetG除外）对每个ARG的衰减都有相同的贡献。铸型中的细菌数量和α多样性（chao1和Shannon）显著减少。Spearman相关分析表明，12个不同的菌门，主要包括酸杆菌、广裂孔菌、热脱隐球菌、氯仿、厚壁菌、纤维性杆菌和蛋白细菌是潜在的ARGs宿主，提示蚯蚓消化EAS过程中宿主的命运和行为在很大程度上决定了ARGs的动态。这些发现增加了我们对蚯蚓肠道消化的理解，认为这是减少EAS中ARGs的一个重要过程，有助于防止它们释放到整个环境中。

      Vermicomposting can significantly attenuate antibiotic resistance genes (ARGs) in the excess activated sludge (EAS). However, the effect of earthworms, especially the effect of gut digestion as a critical step in the vermicomposting process, remains unclarified. The purpose of this study was to investigate the response of ARGs (cell-free and -associated) in EAS to gut digestion of earthworms and to clarify the possible mechanism from the viewpoint of bacterial community through quantitative polymer chain reaction (q-PCR) and high throughput sequencing. Compared to the initial sludge, the earthworm casts were observed to have significantly lower absolute abundances of ARGs, especially qnrS, tetM, and tetX with the removal exceeding 90%. Cell-free and -associated ARGs (except sul1 and tetG) had equivalent contributions to the attenuation of each ARG. Remarkable reductions of bacterial number and alpha diversity (chao1 and Shannon) were detected in the casts. Spearman correlation analysis between the targeted genes and bacterial community indicates that twelve different phyla mainly including Acidobacteria, Euryarchaeota, Deinococcus-Thermus, Chlorobi, Firmicutes, Fibrobacteres, and Proteobacteria are the potential ARGs hosts, suggesting that the fate and behaviour of these hosts during gut digestion of EAS by earthworms substantially determined the dynamics of the ARGs. These findings increase our understanding of earthworm gut digestion as an important process for the attenuation of ARGs in EAS, and contribute towards preventing their release into the total environment.

      https://www.sciencedirect.com/science/article/pii/S0048969719332917?via%3Dihub