河北省典型湿地沉积物中抗生素抗性基因分布特征及其影响因素

Distribution patterns and influencing factors of antibiotic resistance genes in sediments from representative wetlands in Hebei Province

  • 摘要: 抗生素抗性基因(ARGs)在环境中的污染扩散导致的生态安全和健康风险已成为全球关注的热点问题。湿地生态系统作为人类活动与自然环境之间重要的生态屏障, 具有较高的生态、社会和经济价值。本文以河北省典型滨海湖泊湿地(曹妃甸和南大港)和内陆淡水湿地(白洋淀和衡水湖)为研究区域, 采集表层沉积物样品, 采用定量PCR和高通量测序技术, 解析了河北省典型湿地沉积物ARGs的分布特征及其影响因素。结果表明, 在所有湿地沉积物中均检出2种磺胺类、8种四环素类ARGs和1种整合酶基因(intI1)。南大港湿地沉积物中ARGs总丰度均值4.14×108 copies∙g−1 (干土)显著高于曹妃甸1.21×108 copies·g−1 (干土)、白洋淀1.11×108 copies·g−1 (干土)和衡水湖1.97×108 copies·g−1 (干土)沉积物ARGs总丰度(衡水湖采样点1除外) (P<0.05)。四环素类ARGs绝对丰度为8.91×103~8.42×107 copies∙g−1 (干土), 磺胺类ARGs绝对丰度为9.63×105~2.62×107 copies∙g−1 (干土)。intI1基因检出丰度为3.26×105~1.11×108 copies·g−1 (干土), 且intI1基因与tetAtetLsul1sul2基因显著正相关(P<0.05或P<0.01或P<0.001), 说明intI1基因在湿地沉积物ARGs的传播中起着重要作用。此外, 高通量测序结果表明, 曹妃甸和南大港沉积物细菌的Shannon和Simpson指数显著高于衡水湖(P<0.05)。非度量多维度分析(NMDS)结果表明, 曹妃甸、南大港、白洋淀和衡水湖沉积物细菌Beta多样性无显著差异(Anosim: P>0.05)。进一步通过方差分解分析发现, 沉积物理化性质(pH和TP等)和细菌群落对ARGs分布的总解释率为60.78%, 其中细菌群落解释率为37.42%, 说明细菌群落是影响ARGs分布的重要因素。本研究为评估河北省典型湿地沉积物中ARGs的污染现状提供了数据参考, 为保护湿地生态系统安全提供了科学依据。

     

    Abstract: Increasing research is currently focused on the ecological safety and health risks associated with the dissemination of antibiotic resistance genes (ARGs) in the environment. Wetland ecosystems possess significant ecological, social, and economic value as crucial ecological barriers that effectively separate anthropogenic activities from the natural environment. The propagation of ARGs in wetland ecosystems poses a significant threat to both ecosystem integrity and human well-being, and has thus garnered increasing attention. In this study, we analyzed the distribution characteristics of ARGs and their influencing factors in representative coastal wetlands (Caofeidian and Nandagang) as well as inland freshwater wetlands (Baiyangdian and Hengshui lakes) located in Hebei Province using quantitative PCR and high-throughput sequencing techniques. The presence and abundance of ten ARGs, including two sulphonamide resistance genes (sul1 and sul2), eight tetracycline resistance genes (tetA, tetC, tetG, tetL, tetM, tetQ, tetW, and tetX), and one integrase gene (intI1), were detected and quantified in wetland sediments. The average total absolute abundance of ARGs detected in sediments in Nandagang 4.14×108 copies∙g−1 (dry soil) was significantly higher than that in Caofeidian 1.21×108 copies·g−1 (dry soil), Baiyangdian Lake 1.11×108 copies·g−1 (dry soil) and Hengshui Lake 1.97×108 copies·g−1 (dry soil) (not including sampling site 1 in Hengshui Lake) (P<0.05). The absolute abundance of tetracycline resistance genes ranged from 8.91 ×103 to 8.42 ×107 copies∙g−1 (dry soil), while the absolute abundance of sulfonamide resistance genes ranged from 9.63 ×105 to 2.62 ×107 copies∙g−1 (dry soil). Notably, the distribution of ARGs in sediments varied even within the same lake. The absolute abundance of intI1 gene ranged from 3.26×105 to 1.11×108 copies·g−1 (dry soil), and a significant positive correlation was observed between the intI1 gene with tetA, tetL, sul1 and sul2 genes (P<0.05 or P<0.01 or P<0.001). These findings suggest that intI1 plays a crucial role in facilitating the dissemination of sediment ARGs. In addition, high-throughput sequencing revealed that Proteobacteria, Chloroflexi, Bacteroidota, Actinobacteriota, Acidobacteriota, Firmicutes, Desulfobacterota, Gemmatimonadota, Planctomycetota, Verrucomicrobiota, Nitrospirota, and Myxococcota were the predominant bacterial phyla in the sediment samples. These phyla collectively accounted for 89.57%~96.05% of the total sediment bacterial community composition. Lower relative abundances of Proteobacteria and Firmicutes were observed in the coastal wetlands than that in the inland freshwater wetlands (P<0.05), whereas Planctomycetota exhibited the opposite trend. The Shannon and Simpson indices indicated a significantly higher alpha diversity of sediment bacterial communities in Caofeidian and Nandagang compared to Hengshui Lake. However, the NMDS analysis showed no significant differences in beta diversity among the Caofeidian, Nandagang, Baiyangdian Lake and Hengshui Lake sediments (Anosim: P>0.05). Variance partitioning analysis demonstrated that sediment physicochemical properties and bacterial community explained 60.78% of the ARGs distribution variance, with the bacterial community accounting for 37.42%, indicating its dominant role as a driving factor. The distribution of the bacterial community was also significantly influenced by the sediment physicochemical properties, including SOM, TN, and TP. The findings of our study offer valuable data and scientific insights for the assessment of ARGs pollution in typical wetland sediments as well as for the preservation of wetland ecosystem security.

     

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