土壤环境科学实验室知识库

       环境和医疗实践中广泛存在的细菌抗生素抗性已经成为食品安全和人类健康领域的主要威胁。 纳米颗粒 在生活生产中的广泛应用不可避免地 会 释放 纳米颗粒至环境中，引起环境中 累积 纳米颗粒的潜在危险。 本研究 旨在 讨论 纳米颗粒是否共选择 诱导土壤 中 抗生素抗性基因（ antibiotic resistance gene ARG 并 提出以下假设： 1 ）土壤中积累的 纳米颗粒 可以促进土壤微生物抗生素抗性， 2 纳米颗粒 诱 导的土壤微生物抗生素抗性的增强与 纳米颗粒 添加 土壤中 ARG 丰度和 丰富度 的增加有关。
        为了验证这些假设，本研究采用3 种稀土氧化物 纳米 颗粒 rare earth oxidenanoparticle 纳米 氧化镧（ nano La 2 O 3 、 纳米 氧化钕（ nano Nd 2 O 3 ）和 纳米 氧化钆nano Gd 2 O 3 3 种典型农田土壤类型 东北黑土 Mollisol ）、 华北潮土Inceptisol ）和 南方红壤 Ultisol 。 微宇宙 培养 60 天 ，在 5 个时间点采样，分别为0 、 1 、 7 、 30 、 60 天。 通过 土壤呼吸和高通量 定量 P CR 的方法测定了土壤微生物 抗生素 抗性的 响应 ，包括所有 大类 抗生素 ARG 的相对丰度和 丰富度 。
        结果表明：在 检测到的 168 个 ARG s （如四环素 类 和多重耐药类 抗性 基因） 中，40 个 ARG s nano La 2 O 3 处理 8 个， nano Nd 2 O 3 处理 21 个， nano Gd 2 O 3 处理 23 个）丰度 在纳米颗粒 暴露条件 下显 著增加 P < 0.05 ）），表明纳米 颗粒 对土壤微生物群落中抗生素抗性基因 具有选择性 诱导 作用。 可移动遗传元件 mobile gene element MGE的相对丰度与 ARG s 之间存在 显著 正相关 关系 P 0 .05 ），表明水平基因转移horizontal gene transfer HGT 可能有助于 ARG s 在纳米颗粒 处理 土壤中的 增加与 扩散。总之，nano La 2 O 3 nano Nd 2 O 3 和 nano Gd 2 O 3 可以通过共选择和水平基因转移 机制 增加 ARGs ，从而 增强 土壤微生物抗生素抗性 。本 研究结果 预示 稀土氧化物纳米颗粒在 土壤生态系统中的环境和健康风险。

        The booming application of manufactured nanoparticles raises concerns about their unintentionally environmental consequences, one of which is whether nanoparticles will coselectively enrich soil antibiotic resistance genes (ARGs) which may be transferred to human pathogens through food chai n. In order to discuss whether nanoparticles will selectively induce soil antibiotic resistance gene (ARG), the following hypotheses are proposed: 1)Nanoparticles accumulated in soil can promote soil microbial antibiotic resistance, 2)Nanoparticle induce d enhancement of soil microbial antibiotic resistance is associated with increased ARG abundance and diversity in nanoparticle added soil.
         To verify these hypotheses, three rare earth oxide nanoparticles were used in this study: nano La 2 O 3 , nano Nd 2 O 3 , and nano Gd 2 O 3 , three typical farmland black soil ( Mollisol )),fluvo aquic soil ( Inceptisol and r ed s oil (Ultisol). Under pure soil culture conditions, after 60 days of darkroom culture, samples were taken at 5 time points, which were 0, 1, 7, 30, and 60 days, respectively. We examined soil microbial resistance to tetracycline in three agricultural soils after pre exposure to 0 100 mg kg 1 of nanoparticulate La 2 O 3 , Nd 2 O 3 , and Gd 2 O 3 for up to 60 days. Soil microbial responses to antibiotic resistance wer e determined by high
throughput quantitative PCR, including the relative abundance and diversity of all major antibiotic types of ARGs.
         Nanoparticle preexposure promoted soil microbial antibiotic resistance, as reflected by the decreased effects of tetra cycline on soil microbial biomass and activity. Quantification of ARGs by high capacity quantitative polymerase chain reaction revealed that the enhanced antibiotic resistance was attributed to the increased relative abundance and diversity of total ARGs w hich targeted all major classes of antibiotics. Among the 168 observed ARGs, 40 ARGs (8 for nao La 2 O 3 , 21 for Nd 2 O 3 , and 23 for Gd 2 O 3 ) were significantly enriched in the presence of nanoparticles (e.g., tetracycline, and multidrug resistance genes, P < 0.0 5),indicating the selective pressure imposed by nanoparticles in promoting the proliferation of antibiotic resistance genes in soil microbial communities . There was a significantly positive correlation between the relative abundance of mobile gene element s and ARGs ( P < 0.05), suggesting that horizontal gene transfer may have aided the spread and proliferation of ARGs in nanoparticle amended soils. Taken together, these findings demonstrate that nanoparticulate La 2 O 3 , Nd 2 O 3 , and Gd 2 O 3 can aggravate soil mi crobial antibiotic resistance by enriching ARGs through co selection and horizontal gene transfer, and thus forewarn of the environmental and health risks of the rare earth oxide nanoparticles in soil ecosystems.