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(antibiotic resistance genes, 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(P<0.05)。四环素类ARGs绝对丰度为8.91×103 (tetM)~8.42×107 (tetX) copies∙g−1 (干土), 磺胺类ARGs绝对丰度为9.63×105 (sul2)~2.62×107 (sul1) 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), 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。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、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: Escalating research is currently focused on the ecological safety and health risks associated with the dissemination of antibiotic resistance genes (ARGs) in the environment. The wetland ecosystems possess significant ecological, social, and economic values as a crucial ecological barrier that effectively separates anthropogenic activities from the natural environment. The propagation of ARGs whithin wetland ecosystems poses a significantly threat to both ecosystem integrity and human well-being, thus garnering increasing attention. In this study, we conducted an analysis of the distribution characteristics of ARGs and their influencing factors in representative coastal wetlands (Caofeidian and Nandagang) as well as inland freshwater wetlands (Baiyangdian Lake and Hengshui Lake) located in Hebei Province, utilizing quantitative PCR and high-throughput sequencing techniques. The presence and abundance of ten ARGs, including two sulfonamide resistance genes (sul1 and sulII), eight tetracycline resistance genes (tetA, tetC, tetG, tetL, tetM, tetQ, tetW, tetX), as well as one integrase gene (intI1) were detected and quantified in wetland sediments. The total absolute abundance of ARGs in Nandagang sediments (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) sediments (P<0.05). The absolute abundance of tetracycline resistance genes ranged from 8.91 ×103 (tetM) to 8.42 ×107 (tetX) copies∙g−1 dry soil, while the absolute abundance of sulfonamide resistance genes ranged from 9.63 ×105 (sul2) to 2.62 ×107 (sul1) copies∙g−1 dry soil. Notably, the distribution of ARGs in sediments varied even in 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 and the tetA, tetL, sul1 and sul2 genes (P<0.05). These findings suggested that intI1 gene may play a crucial role in facilitating the dissemination of sediment ARGs. In addition, high-throughput sequencing results revealed that Proteobacteriota, Chloroflexi, Bacteroidota, Actinobacteriota, Acidobacteriota, Firmicutes, Desulfobacterota, Gemmatimonadota, Planctomycetota, Verrucomicrobiota, Nitrospirota, Myxococcota were the predominant bacterial phyla in the sediment samples. These phyla collectively accounted for 89.57% (NDG1)~96.05% (CFD1) of the total sediment bacterial community composition in the sediments. Lower relative abundances of Proteobacteriota and Firmicutes were observed in coastal wetlands compared to freshwater wetlands (P<0.05), while Planctomycetota exhibited an opposite trend. The Shannon and Simpson indices indicated significantly higher Alpha diversity of sediment bacteria communities in Caofeidian and Nandagang compared to Hengshui Lake. However, NMDS analysis showed no significant differences in Beta diversity among Caofeidian, Nandagang, Baiyangdian Lake, and Hengshui Lake sediments (P>0.05). Variation partitioning analysis demonstrated that sediment physicochemical properties and bacterial community explained a total of 60.78% of ARGs distribution variance, with bacterial community accounting for 37.42%, indicating its dominant role as a driving factor. The distribution of bacterial community was also significantly influenced by sediment physicochemical properties including SOM, TN, and TP. The findings of our study offer valuable data and scientific insights for the assessment of ARG pollution in typical wetland sediments, as well as for the preservation of wetland ecosystem security.

     

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