Liu Shujing, Chen Quanrui, Dong Changjie, Qiu Xuanyun, Li Wenhao, Tang Kai
State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, China.
State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, China.
Mar Pollut Bull. 2025 Jul 15;220:118445. doi: 10.1016/j.marpolbul.2025.118445.
Oxygen loss disrupts marine ecosystems, threatening biodiversity and causing mass mortality of marine life. Antibiotic resistance genes (ARGs) pose a significant threat to human health by promoting the spread of resistant pathogens, making infections harder to treat and increasing mortality risks. However, the interplay between deoxygenation and ARG dynamics remains poorly understood. In this study, we employed time-series metagenomics to investigate the responses of ARG profiles in free-living (FL) and particle-associated (PA) fraction to oxygen loss during a 22-day summer deoxygenation event in the East China Sea. In total, we identified 1,186 ARG subtypes and 2,279 mobile genetic element (MGE) subtypes. The most dominant resistance classes of antibiotics were multidrug (23.5%), followed by tetracycline (15%), macrolide-lincosamide-streptogramin (13.4%), peptide (10.3%), glycopeptide (8.7%), aminoglycoside (7.3%), and beta-lactam (4.9%). We found that ARG richness in FL fraction increased with declining oxygen levels, particularly for beta-lactam and multidrug class, while no significant relationship was observed in the PA fraction. Although the total relative abundance of ARGs in both fraction showed no significant oxygen dependence, beta-lactam and multidrug resistance genes in FL fraction significantly increased with oxygen loss. Co-occurrence network analysis revealed stronger positive associations between ARGs and MGEs in the FL fraction, suggesting enhanced gene transfer among environmental bacteria. Furthermore, neutral community model analysis indicated that stochastic processes also played an interactive role in shaping ARG composition dynamics in both bacterial fractions. Our findings provide evidence that coastal deoxygenation preferentially enriches high-risk ARGs (e.g., beta-lactamase genes) in FL bacteria through MGE-mediated transfer, highlighting escalating antibiotic resistance risks that threaten both ecosystem and human health under climate warming. This study offers a framework for size-fractionated ARG monitoring and targeted mitigation strategies in coastal ecosystems.
氧气流失破坏海洋生态系统，威胁生物多样性并导致海洋生物大量死亡。抗生素抗性基因（ARGs）通过促进耐药病原体的传播，对人类健康构成重大威胁，使感染更难治疗并增加死亡风险。然而，脱氧与ARGs动态之间的相互作用仍知之甚少。在本研究中，我们采用时间序列宏基因组学方法，调查了在东海为期22天的夏季脱氧事件中，自由生活（FL）和颗粒相关（PA）部分的ARGs谱对氧气流失的响应。我们总共鉴定出1186种ARGs亚型和2279种移动遗传元件（MGEs）亚型。最主要的抗生素抗性类别是多药抗性（23.5%），其次是四环素（15%）、大环内酯-林可酰胺-链阳霉素（13.4%）、肽（10.3%）、糖肽（8.7%）、氨基糖苷（7.3%）和β-内酰胺（4.9%）。我们发现，FL部分的ARGs丰富度随氧气水平下降而增加，特别是β-内酰胺类和多药抗性类别，而在PA部分未观察到显著关系。尽管两个部分中ARGs的总相对丰度均未显示出明显的氧气依赖性，但FL部分中的β-内酰胺和多药抗性基因随氧气流失显著增加。共现网络分析表明，FL部分中ARGs与MGEs之间的正相关更强，表明环境细菌之间的基因转移增强。此外，中性群落模型分析表明，随机过程在塑造两个细菌部分的ARGs组成动态中也发挥了交互作用。我们的研究结果证明，沿海脱氧通过MGE介导的转移优先富集FL细菌中的高风险ARGs（如β-内酰胺酶基因），突出了在气候变暖下威胁生态系统和人类健康的抗生素抗性风险不断升级。本研究为沿海生态系统中按大小分级的ARGs监测和有针对性的缓解策略提供了框架。
