摘要

       在淡水系统中，抗生素抗性基因 (ARG) 和蓝藻大量繁殖引起了全球公共卫生的关注。蓝藻大量繁殖可以极大地影响细菌分类群落，但关于大量繁殖对抗生素抗性功能群落的影响知之甚少。在这项研究中，使用高通量方法在亚热带水库中同时研究了水华和非水华条件下自由生活 (FL) 和颗粒附着 (PA) 细菌中的 ARG。总共检测到 145 个 ARG 和 9 个移动遗传元件 (MGE)。其中最多样化和占优势的（68.93%）是多药耐药基因和外排泵机制。与非开花期相比，开花期 FL 和 PA 细菌中 ARG 的丰富度显着降低。开花条件下FL细菌中ARGs的丰度显着低于非开花期，但PA细菌中ARGs的丰度保持不变。更重要的是，与 FL 细菌相比，PA 细菌中的抗性功能群落受蓝藻水华的影响更大，尽管 >96% 的 ARG 在 FL 和 PA 细菌或水华和非水华时期共享。我们还比较了分类学和功能之间的群落组成，发现抗生素抗性群落高度可变，开花期和非开花期之间的相似性低于分类学组成中的相似性，FL 细菌除外。总之，蓝藻大量繁殖似乎对 FL 细菌中的 ARG 丰度具有更强的抑制作用，并对 PA 细菌中的抗生素抗性群落组成产生更强的影响。我们的结果进一步表明，中性和选择性过程都会相互作用地影响 FL 和 PA 细菌的 ARG 组成动态。然而，FL 细菌的抗生素抗性群落在开花事件后表现出比 PA 细菌更高水平的时间随机性。因此，我们强调细菌生活方式是一种重要机制，导致抗生素抗性群落对蓝藻水华的不同反应。

       In freshwater systems, both antibiotic resistance genes (ARGs) and cyanobacterial blooms attract global public health concern. Cyanobacterial blooms can greatly impact bacterial taxonomic communities, but very little is known about the influence of the blooms on antibiotic resistance functional community. In this study, the ARGs in both free-living (FL) and particle-attached (PA) bacteria under bloom and non-bloom conditions were simultaneously investigated in a subtropical reservoir using high-throughput approaches. In total, 145 ARGs and 9 mobile genetic elements (MGEs) were detected. The most diverse and dominant of which (68.93%) were multidrug resistance genes and efflux pump mechanism. The richness of ARGs in both FL and PA bacteria was significantly lower during the bloom period compared with non-bloom period. The abundance of ARGs in FL bacteria was significantly lower under bloom condition than in the non-bloom period, but the abundance of ARGs in PA bacteria stayed constant. More importantly, the resistant functional community in PA bacteria was more strongly influenced by the cyanobacterial bloom than in the FL bacteria, although >96% ARGs were shared in both FL and PA bacteria or both bloom and non-bloom periods. We also compared the community compositions between taxonomy and function, and found antibiotic resistant communities were highly variable and exhibited lower similarity between bloom and non-bloom periods than seen in the taxonomic composition, with an exception of FL bacteria. Altogether, cyanobacterial blooms appear to have stronger inhibitory effect on ARG abundance in FL bacteria, and stronger influence on antibiotic resistant community composition in PA bacteria. Our results further suggested that both neutral and selective processes interactively affected the ARG composition dynamics of the FL and PA bacteria. However, the antibiotic resistant community of FL bacteria exhibited a higher level of temporal stochasticity following the bloom event than PA bacteria. Therefore, we emphasized the bacterial lifestyles as an important mechanism, giving rise to different responses of antibiotic resistant community to the cyanobacterial bloom.

https://www.sciencedirect.com/science/article/pii/S0160412018300886