摘要

      在淡水系统中，抗生素抗性基因（ARGs）和蓝藻水华引起了全球公共卫生关注。蓝藻水华对细菌分类群落的影响很大，但对其对抗生素抗性功能群落的影响知之甚少。本研究以亚热带水库为研究对象，采用高通量的方法，同时研究了水华和非水华条件下自由生活菌（FL）和颗粒附着菌（PA）的ARGs。共检测到145个精氨酸和9个流动基因元件。其中以多药耐药基因和外排泵机制最具多样性和优势（68.93%）。开花期FL和PA细菌ARGs含量均显著低于非开花期。在开花条件下，FL菌的ARGs含量显著低于非开花期，但PA菌的ARGs含量保持恒定。更重要的是，PA细菌的抗性功能群落受蓝藻水华的影响比FL细菌的更大，尽管FL和PA细菌或水华和非水华细菌共有超过96%的arg。我们还比较了分类学和功能学之间的群落组成，发现抗菌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，但FL细菌除外。综上所述，蓝藻水华似乎对FL细菌中的精氨酸丰度有更强的抑制作用，对PA细菌中的抗生素抗性群体组成有更强的影响。我们的结果进一步表明，中性和选择性过程都会交互影响FL和PA细菌的ARG组成动态。然而，FL菌的抗菌素抗性群体在开花事件后表现出比PA菌更高的时间随机性。因此，我们强调细菌的生活方式是一个重要的机制，导致耐药群体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?via%3Dihub