Metal(loid)s can promote the spread and enrichment of antibiotic resistance genes (ARGs) in the environment through a co-selection effect. However, it remains unclear whether exposure of microorganisms to varying concentrations of selenium (Se), an essential but potentially deleterious metal(loid) to living organisms, can influence the migration and distribution of ARGs in forest soils. Precisely 235 ARGs conferring resistance to seven classes of antibiotics were detected along a Se gradient (0.06–20.65 mg kg−1) across 24 forest soils. (flor)/(chlor)/(am)phenicol resistance genes were the most abundant in all samples. The total abundance of ARGs first increased and then decreased with an elevated available Se content threshold of 0.034 mg kg−1 (P = 2E−05). A structural equation model revealed that the dominant mechanism through which Se indirectly influences the vertical migration of ARGs is by regulating the abundance of the bacterial community. In addition, the methylation of Se (mediated by tehB) and the repairing of DNA damages (mediated by ruvB and recG) were the dominant mechanisms involved in Se resistance in the forest soils. The co-occurrence network analysis revealed a significant correlated cluster between Se-resistance genes, MGEs and ARGs, suggesting the co-transfer potential. Lelliottia amnigena YTB01 isolated from the soil was able to tolerate 50 μg mL−1 ampicillin and 1000 mg kg−1 sodium selenite, and harbored both Se resistant genes and ARGs in the genome. Our study demonstrated that the spread and enrichment of ARGs are enhanced under moderate Se pressure but inhibited under severe Se pressure in the forest soil (threshold at 0.034 mg kg−1 available Se content). The data generated in this pilot study points to the potential health risk associated with Se contamination and its associated influence on ARGs distribution in soil.

中文翻译：

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自然硒胁迫对含硒森林土壤抗生素耐药性变化的影响

金属（样体）可以通过共选择效应促进抗生素抗性基因（ARG）在环境中的传播和富集。然而，目前尚不清楚微生物暴露于不同浓度的硒（Se），一种对生物体必不可少但可能有害的金属（类物质），是否会影响 ARGs 在森林土壤中的迁移和分布。在 24 个森林土壤中沿着硒梯度（0.06-20.65 mg kg-1）检测到 235 个 ARG，它们对七类抗生素具有抗性。(flor)/(chlor)/(am)phenicol 抗性基因在所有样品中是最丰富的。ARGs 的总丰度先增加后减少，有效硒含量阈值为 0.034 mg kg-1 (P = 2E-05)。结构方程模型显示，硒间接影响ARGs垂直迁移的主要机制是通过调节细菌群落的丰度。此外，Se 的甲基化（由 tehB 介导）和 DNA 损伤的修复（由 ruvB 和 recG 介导）是森林土壤中硒抗性的主要机制。共现网络分析揭示了硒抗性基因、MGEs 和 ARGs 之间的显着相关簇，表明共转移潜力。从土壤中分离出的 Lelliottia amnigena YTB01 能够耐受 50 μg mL-1 氨苄青霉素和 1000 mg kg-1 亚硒酸钠，并且在基因组中含有抗硒基因和 ARGs。我们的研究表明，ARGs 的扩散和富集在中等硒压力下得到增强，但在森林土壤中的严重硒压力下受到抑制（阈值为 0.034 mg kg-1 有效硒含量）。该试点研究中产生的数据指出了与硒污染相关的潜在健康风险及其对土壤中 ARGs 分布的相关影响。