摘要

这项研究旨在揭示抗生素抗性基因（ARGs）及其横向和纵向转移相关基因（mobilome和细菌宿主）对厌氧消化（AD）从嗜温到嗜热转化的反应。利用宏基因组测序技术研究了嗜温污泥和嗜热污泥的抗性和流动性，并用定量PCR和454-焦磷酸测序技术进一步的研究了24个代表性过氧化氢酶在过渡期属于1类整合子和细菌属的变化。温度升高后，消化污泥中的抗氧化剂丰度从125.97ppm（第0天，嗜温）降至50.65ppm（第57天，嗜热），除了氨基糖苷类抗性基因外，大部分ARG类型减少。嗜热性污泥中的嗜热菌污泥也有较小的流动性，包括质粒，插入序列和整合子，这表明嗜热性条件下ARG的水平转移潜能较低。另一方面，通过网络分析表明，13个细菌属的总数量可能是嗜热菌污泥中的23.27％，而嗜热菌泥中则为11.92％，表明ARGs垂直扩展的宿主数量较少温度升高后。这些结果表明，嗜热性AD的抵抗素丰度降低可能与ARGs水平和垂直转移能力的下降有关。

This study aimed to reveal how antibiotic resistance genes (ARGs) and their horizontal and vertical transfer-related items (mobilome and bacterial hosts) respond to the transformation of anaerobic digestion (AD) from mesophilic to thermophilic using one-step temperature increase. The resistomes and mobilomes of mesophilic and thermophilic sludge were investigated using metagenome sequencing, and the changes in 24 representative ARGs belonging to three categories, class 1 integron and bacterial genera during the transition period were further followed using quantitative PCR and 454-pyrosequencing. After the temperature increase, resistome abundance in the digested sludge decreased from 125.97 ppm (day 0, mesophilic) to 50.65 ppm (day 57, thermophilic) with the reduction of most ARG types except for the aminoglycoside resistance genes. Thermophilic sludge also had a smaller mobilome, including plasmids, insertion sequences and integrons, than that of mesophilic sludge, suggesting the lower horizontal transfer potential of ARGs under thermophilic conditions. On the other hand, the total abundance of 18 bacterial genera, which were suggested as the possible hosts for 13 ARGs through network analysis, decreased from 23.27% in mesophilic sludge to 11.92% in thermophilic sludge, indicating fewer hosts for the vertical expansion of ARGs after the increase in temperature. These results indicate that the better reduction of resistome abundance by thermophilic AD might be associated with the decrease of both the horizontal and vertical transferability of ARGs.

http://www.sciencedirect.com/science/article/pii/S0043135416302226