Metal-based nanoparticles exhibiting antimicrobial activity are of emerging concern to human and environmental health. In addition to their direct adverse effects to plants and animals, indirect effects resulting from disruption of beneficial host-microbiota interactions may contribute to the toxicity of these particles. To explore this hypothesis, we compared the acute toxicity of silver and zinc oxide nanoparticles (nAg and nZnO) to zebrafish larvae that were either germ-free or colonized by microbiota. Over two days of exposure, germ-free zebrafish larvae were more sensitive to nAg than microbially colonized larvae, whereas silver ion toxicity did not differ between germ-free and colonized larvae. Using response addition modeling, we confirmed that the protective effect of colonizing microbiota against nAg toxicity was particle-specific. Nearly all mortality among germ-free larvae occurred within the first day of exposure. In contrast, mortality among colonized larvae increased gradually over both exposure days. Concurrent with this gradual increase in mortality was a marked reduction in the numbers of live host-associated microbes, suggesting that bactericidal effects of nAg on protective microbes resulted in increased mortality among colonized larvae over time. No difference in sensitivity between germ-free and colonized larvae was observed for nZnO, which dissolved rapidly in the exposure medium. At sublethal concentrations, these particles moreover did not exert detectable bactericidal effects on larvae-associated microbes. Altogether, our study shows the importance of taking host-microbe interactions into account in assessing toxic effects of nanoparticles to microbially colonized hosts, and provides a method to screen for microbiota interference with nanomaterial toxicity.

中文翻译：

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菌落定殖可保护斑马鱼幼虫免受银纳米颗粒的毒性。

表现出抗微生物活性的基于金属的纳米颗粒已成为人类和环境健康关注的焦点。除了对植物和动物的直接不利影响外，有益宿主微生物群相互作用的破坏所产生的间接影响也可能导致这些颗粒的毒性。为了探究这一假设，我们比较了氧化银和氧化锌纳米粒子（nAg和nZnO）对斑马鱼幼虫的急性毒性，这些斑马鱼幼虫是无菌的或被微生物群定殖。在暴露的两天中，无菌的斑马鱼幼虫比微生物定居的幼虫对nAg更为敏感，而无菌的和定居的幼虫之间的银离子毒性没有差异。使用响应添加模型，我们确认了定居微生物群对nAg毒性的保护作用是颗粒特异性的。无菌幼虫中几乎所有的死亡率都在接触的第一天发生。相反，在两个接触日中，定居幼虫的死亡率逐渐增加。与死亡率的逐渐增加同时，与宿主宿主相关的活菌的数量也明显减少，这表明nAg对保护性微生物的杀菌作用会导致定居幼虫的死亡率随时间增加。对于在暴露介质中迅速溶解的nZnO，未观察到无菌幼虫和定居幼虫之间的敏感性差异。在致死浓度下，这些颗粒还没有对幼虫相关微生物产生可检测的杀菌作用。共，