摘要
      抗生素耐药性基因（ARG）污染是一个严重的环境问题，水平基因转移是进化的驱动力。理论上，由于真核生物和原核生物之间的系统发育距离，真核微藻可能是一种天然屏障，在共生细菌之间的ARG转移中发挥负面作用，从而降低废水处理过程中污泥中ARG的丰度。然而，这一假设远未得到证实，需要进行实验验证，因此本研究基于好氧颗粒反应器研究了真核微藻（Scenedesmus）对共生细菌ARG谱的影响。结果表明，Scenedesmus共生会影响细菌的ARG多样性，好氧颗粒污泥（AG）组和藻类-细菌颗粒群落（AAG）组的ARG检测数量分别为45–53和44–47。在相对丰度方面，在添加链霉素、阿奇霉素和万古霉素的系统中，目标微藻共生后，ARGs的总丰度分别从1.17×10°、2.69×10°和1.36×10−1显著降低到6.53×10−、9.64×10−和1.04×10–1（P<0.05），冗余分析表明，真核微藻是解释ARG相对丰度变化的重要因素（P<0.05），占ARG变异的15.3%。此外，结果表明，除四环素处理系统外，在其他五种抗生素的胁迫下，AAG中MGEs的总相对丰度为3.54×10−2-7.13×10−1，均显著低于AG（8.38×10−2-1.59×10°）。ARGs与移动遗传元件（MGEs）之间的正相关关系比ARGs和优势细菌之间的正相关性更显著。
Abstract
Antibiotic resistance gene (ARG) pollution is critical environmental problem, and horizontal gene transfer acts as a driving evolutionary force. In theory, due to the phylogenetic distance between eukaryotes and prokaryotes, eukaryotic microalgae can be a natural barrier that plays a negative role in ARG transfer among the symbiotic bacteria to decrease ARG abundance in sludge during wastewater treatment. However, this hypothesis is far from proven and needs to be tested experimentally, so this study investigated the influence of eukaryote microalgae (Scenedesmus) on the ARG profile of symbiotic bacteria based on aerobic granular reactor. The results indicated that Scenedesmus symbiosis could affect ARG diversity of bacteria, and the detected numbers of ARG in aerobic granular sludge (AG) group and algae-bacteria granular consortia (AAG) group were 45–53 and 44–47, respectively. In terms of relative abundance, after target microalgae symbiosis, the total abundance of ARGs significantly decreased from 1.17 × 10°, 2.69 × 10° and 1.36 × 10−1 to 6.53 × 10−1, 9.64 × 10−1 and 1.04 × 10−1 in the systems with the addition of streptomycin, azithromycin and vancomycin, respectively (P < 0.05), yet there was no significant difference between AG and AAG under the stress of ampicillin, sulfamethazine and tetracycline (P > 0.05). Redundancy analysis showed that the eukaryotic microalgae were significant factor explaining the change in ARG relative abundance (P < 0.05), which contributed 15.3% of ARG variation. Furthermore, the results show that, except for the tetracycline treatment system, the total relative abundances of MGEs in the AAG under the stress of the other five antibiotics were 3.54 × 10−2-7.13 × 10−1, which were all significantly lower than those in the AG (8.38 × 10−2-1.59 × 10°). There was a more significant positive correlation relationship between ARGs and mobile genetic elements (MGEs) than that between ARGs and dominated bacteria.

https://www.sciencedirect.com/science/article/abs/pii/S0269749122004353