Characterizing the impact of nanoplastics to organism health is important to understand the consequences of the environmental plastic waste problem. This article examines the impact of nano-polystyrene (nano-PS; 159 ± 0.9 nm diameter) to ecologically relevant bacteria Shewanella oneidensis. Bacterial viability was evaluated using a growth-based assay. Riboflavin secretion is a critical cell function of S. oneidensis, serving as an electron mediator in anaerobic respiration and/or as a signaling molecule when the bacteria are under stress. Thus, changes in cellular function were monitored through riboflavin secretion in order to evaluate toxic responses that may not result in cell death. Under aerobic and anaerobic exposures (4, 8, or 12 h), the viability of the S. oneidensis was minimally changed as compared to the control, while the concentration of riboflavin secreted varied with exposure dose. In order to determine if this was a specific response to nanoplastic particles, opposed to a response to either particles or plastic more generally, we exposed the system to colloidal TiO2 nanoparticles and polystyrene and polyethylene thin films. We confirmed that riboflavin secretion trends were specific to nano-PS and not to these other materials, which showed no significant changes. We investigated the association of the nano-PS with ICP-MS using Pd that was chemically incorporated into the model nanoplastics. While 59.2% of the nano-PS were found in the non-cellular culture media, 7.0 and 6.6% was found associated with the loosely and tightly bound extracellular polymeric substance, respectively. There was significantly more nano-PS (10.9%) strongly associated with the cells. Taken together, we found that nano-PS had minimal impacts to viability but caused a significant change in the function of S. oneidensis that can be related to the nano-PS attached or in proximity to the bacterium. These trends are consistent between aerobic and anaerobic cultures, signifying that the stress response of S. oneidensis can be generalized between different environmental compartments. This work highlights that the association of nanoplastic materials with microorganisms may modify the cellular function that could ultimately be an impact to ecosystem health.

中文翻译：

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纳米塑料对模型细菌 Shewanella oneidensis 活力和核黄素分泌的影响

表征纳米塑料对生物体健康的影响对于了解环境塑料废物问题的后果很重要。本文研究了纳米聚苯乙烯（纳米 PS；直径 159 ± 0.9 nm）对生态相关细菌 Shewanella oneidensis 的影响。使用基于生长的测定法评估细菌活力。核黄素分泌是 S. oneidensis 的关键细胞功能，在无氧呼吸中充当电子介质和/或在细菌处于压力下时充当信号分子。因此，通过核黄素分泌监测细胞功能的变化，以评估可能不会导致细胞死亡的毒性反应。在有氧和无氧暴露（4、8 或 12 小时）下，与对照相比，S. oneidensis 的生存力变化很小，而分泌的核黄素浓度随暴露剂量而变化。为了确定这是否是对纳米塑料颗粒的特定反应，而不是更普遍地对颗粒或塑料的反应，我们将系统暴露于胶体 TiO2 纳米颗粒以及聚苯乙烯和聚乙烯薄膜。我们证实核黄素的分泌趋势是特定于纳米 PS 而不是这些其他材料，这表明没有显着变化。我们使用化学结合到模型纳米塑料中的 Pd 研究了纳米 PS 与 ICP-MS 的关联。虽然在非细胞培养基中发现了 59.2% 的纳米 PS，但分别发现 7.0% 和 6.6% 与松散和紧密结合的细胞外聚合物相关。有明显更多的纳米 PS（10. 9%) 与细胞密切相关。综上所述，我们发现纳米 PS 对生存力的影响很小，但导致 S. oneidensis 的功能发生显着变化，这可能与附着或靠近细菌的纳米 PS 相关。这些趋势在好氧和厌氧培养之间是一致的，这表明 S. oneidensis 的应激反应可以在不同的环境隔间之间推广。这项工作强调，纳米塑料材料与微生物的关联可能会改变最终可能对生态系统健康产生影响的细胞功能。这些趋势在需氧和厌氧培养之间是一致的，这表明 S. oneidensis 的应激反应可以在不同的环境区室之间推广。这项工作强调，纳米塑料材料与微生物的关联可能会改变最终可能对生态系统健康产生影响的细胞功能。这些趋势在好氧和厌氧培养之间是一致的，这表明 S. oneidensis 的应激反应可以在不同的环境隔间之间推广。这项工作强调，纳米塑料材料与微生物的关联可能会改变最终可能对生态系统健康产生影响的细胞功能。