Ocean contamination by micro- and nanoplastics represents a potential threat to marine biota, from bacterial communities to higher organisms. In this work, the effect of in vivo exposure of Mytilus galloprovincialis to amino modified nanopolystyrene (PS–NH2) (10 μg/L, 96 h) on hemolymph immune parameters and microbiota composition were investigated. Nanoplastics significantly affected immune parameters (decreased phagocytosis, increased ROS and lysozyme activity, inhibition of NO production). These changes were associated with a shift in hemolymph microbiota composition, with increase in some genera (Arcobacter-like, Psychrobium, Vibrio), and decreases in others (Shewanella, Mycoplasma). The results indicate that exposure to nanoplastics can impact on the microbiome of marine bivalves, and suggest that downregulation of immune defences induced by PS-NH2 may favour potentially pathogenic bacteria. These data underline how exposure to nanoplastics may represent a potential threat to the complex interplay between innate immunity and host microbiota, thus affecting the homeostatic processes involved in maintenance of organism health.

微生物和纳米塑料对海洋的污染代表了从细菌群落到高等生物对海洋生物群的潜在威胁。在这项工作中，研究了盖洛米氏菌在氨基修饰的纳米聚苯乙烯（PS-NH2）（10μg/ L，96 h）的体内暴露对淋巴免疫参数和微生物群组成的影响。纳米塑料显着影响免疫参数（吞噬作用降低，ROS和溶菌酶活性增加，NO生成抑制）。这些变化与血淋巴微生物群组成的变化有关，某些属增加（类杆菌属，Psychrobium，弧菌），而另一些属减少（Shewanella，支原体））。结果表明，暴露于纳米塑料可能会影响海洋双壳类动物的微生物组，并表明PS-NH2诱导的免疫防御的下调可能有利于潜在的致病细菌。这些数据强调了纳米塑料的暴露如何可能会对先天免疫力和宿主微生物群之间复杂的相互作用造成潜在威胁，从而影响维持生物体健康的体内平衡过程。