Key Laboratory of Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, China.
Key Laboratory of Three Gorges Reservoir Region's Eco-environment, Ministry of Education, Chongqing University, Chongqing, 400045, China.
Environ Pollut. 2024 Dec 15;363(Pt 2):125214. doi: 10.1016/j.envpol.2024.125214. Epub 2024 Oct 30.
As the intrinsic property of microorganisms, antibiotic resistance genes (ARGs) are fundamentally coupled to microbially-linked biogeochemical processes within ecosystems. However, human activities often obscure the natural distribution of ARGs through deterministic selective pressures. The deep-sea basin of the western Pacific Ocean is one of the least disturbed areas globally by human activities, providing a natural laboratory to investigate the intrinsic mechanisms governing ARGs in natural environments. In this study, we analyzed bacterial community and ARG diversity in 15 surface sediment samples from three deep-sea basins in the western Pacific Ocean. The relative abundance of ARGs in the surface sediments ranged from 3.10 × 10 to 5.37 × 10 copies/16S rRNA copies, with multidrug and β-lactam resistance genes dominated in all samples (49.06%-100%). The bacteria were mainly dominated by the Proteobacteria. The principal coordinate analysis (PCoA) showed significant spatial heterogeneity of ARGs and bacteria among the three basins. Null model, neutral community models (NCM), and normalized stochasticity ratio (NST) indicated that bacterial community was dominated by stochastic assembly, driven by geographic barriers leading to independent evolution. Conversely, the NST revealed that the ARGs profile was mainly shaped by deterministic processes. Environmental factors are more crucial than geographical factors and bacterial community for ARG occurrence among the selected factors. Meanwhile, we found that the spread of ARGs was mainly through vertical gene transfer in the pre-antibiotic era. The disparity between the assembly processes of bacterial community and ARGs may be attributed to the fact that ARG hosts were not the dominant bacteria in the community. This study first reported the distribution and assembly processes of ARGs and bacterial community in surface sediments of the western Pacific.
作为微生物的固有特性，抗生素耐药基因（ARGs）与生态系统中微生物相关的生物地球化学过程密切相关。然而，人类活动常常通过确定性的选择压力掩盖 ARGs 的自然分布。西太平洋深海盆地是受人类活动干扰最小的地区之一，为研究自然环境中 ARGs 的内在机制提供了一个天然实验室。在这项研究中，我们分析了来自西太平洋三个深海盆地的 15 个表层沉积物样本中的细菌群落和 ARG 多样性。表层沉积物中 ARGs 的相对丰度范围为 3.10×10 至 5.37×10 拷贝/16S rRNA 拷贝，所有样本均以多药和β-内酰胺耐药基因为主（49.06%-100%）。细菌主要以变形菌门为主。主坐标分析（PCoA）显示，三个盆地之间的 ARGs 和细菌具有明显的空间异质性。零模型、中性群落模型（NCM）和归一化随机比（NST）表明，细菌群落主要由随机组装主导，由地理障碍驱动，导致独立进化。相反，NST 表明 ARGs 谱主要由确定性过程塑造。在所选因素中，环境因素比地理因素和细菌群落对 ARG 出现更为重要。同时，我们发现 ARGs 的传播主要是通过前抗生素时代的垂直基因转移。细菌群落和 ARGs 的组装过程之间的差异可能归因于 ARG 宿主不是群落中的优势细菌。本研究首次报道了西太平洋表层沉积物中 ARGs 和细菌群落的分布和组装过程。
