摘要

       本研究旨在揭示抗生素抗性基因 (ARG) 及其水平和垂直转移相关项目（移动组和细菌宿主）如何通过一步升温来响应厌氧消化 (AD) 从嗜温转化为高温。使用宏基因组测序研究了嗜温和嗜热污泥的抵抗组和移动组，并使用定量 PCR 和 454-焦磷酸测序进一步跟踪了过渡期间属于三类、1 类整合子和细菌属的 24 个代表性 ARG 的变化。温度升高后，消化污泥中的抗性组丰度从 125.97 ppm（第 0 天，嗜温）下降到 50.65 ppm（第 57 天，嗜热），除氨基糖苷类抗性基因外，大多数 ARG 类型都减少了。与嗜温污泥相比，嗜热污泥还具有更小的移动组，包括质粒、插入序列和整合子，这表明在高温条件下 ARG 的水平转移潜力较低。另一方面，通过网络分析被认为是 13 个 ARG 可能宿主的 18 个细菌属的总丰度从中温污泥中的 23.27% 下降到高温污泥中的 11.92%，表明 ARG 垂直扩展的宿主较少温度升高后。这些结果表明，嗜热 AD 更好地降低抵抗组丰度可能与 ARG 水平和垂直可转移性的降低有关。

       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.

https://www.sciencedirect.com/science/article/abs/pii/S0043135416302226