Extracellular polymeric substance mediating nanoplastics-promoted short-term Porphyridium growth disrupts marine carbon and phosphorus migration

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-05-18 DOI:10.1016/j.watres.2025.123860

Huankai Li , Wei Wang , Feng Zhang , Leijian Chen , Fangfang Miao , Hongzhi Zhao , Zhu Yang , Zongwei Cai

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Abstract

The ecotoxicity of nanoplastics (NPs) on marine microalgae has been extensively explored recently, yet the mechanisms driving short-term growth improvement caused by NPs remain poorly understood. In the present study, we observed that a relatively high concentration (10 mg/L) of the green fluorescently labeled fresh polyamide-polymethyl methacrylate polymer blend (w/w 21:4) NPs beads (200 nm) significantly enhanced the cell density of Porphyridium cruentum (42.1 %) by alleviating reactive oxygen species generation, chlorophyll degradation, and photoinhibition. An increase in the sticky bounded exopolysaccharides (b-EPs) surrounding P. cruentum surface enhanced NP adsorption within five hours of exposure, with –CH₃ bond in phospholipids/glycolipids and polysaccharides of b-EPs supporting the adsorption to mitigate photoinhibition. Increased free exopolysaccharides (EPs) removed inorganic and organic carbon and 48 % of dissolved organic matter (DOM), encapsulating NPs into sediments while cooperating with pH elevation. However, short-term growth promotion resulted in cell shading and phosphorous deficiency after 12 days of cultivation. Consequently, the photosynthesis-antenna proteins pathway and energy metabolites were downregulated, whereas the transmembrane transport and receptor activities of phosphate and calcium signal pathways were upregulated to maintain growth, achieving balance in the 1 mg/L group. The significantly upregulated steroid biosynthesis promoted the hydrophobicity of plasma membranes and reduced the permeability for water-soluble ions, exacerbating phosphorus deficiency. The downregulation of the Calvin cycle shifted the total carbon metabolism and carbon migration, reducing photosynthesis and respiration but accumulating starch to counteract cell shading and phosphorus deficiency. These findings provide novel insights into the mechanisms underlying the short-term growth stimulation and long-term potential toxic effects of NPs on marine microalgae, thus altering marine carbon and phosphorus cycles.

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胞外聚合物介导纳米塑料促进的卟啉短期生长破坏海洋碳和磷迁移

近年来，人们对纳米塑料对海洋微藻的生态毒性进行了广泛的研究，但对纳米塑料促进海洋微藻短期生长的机制却知之甚少。在本研究中，我们观察到相对高浓度（10 mg/L）的绿色荧光标记的新鲜聚酰胺-聚甲基丙烯酸甲酯聚合物混合物（w/w 21:4） NPs珠（200 nm）通过减轻活性氧的产生、叶绿素降解和光抑制，显著提高了cruentum卟啉的细胞密度（42.1%）。在暴露5小时内，粘有结合的外多糖（b-EPs）的增加增强了NP的吸附，磷脂/糖脂和b-EPs多糖中的-CH3键支持吸附以减轻光抑制。增加的游离胞外多糖（EPs）去除无机碳和有机碳以及48%的溶解有机质，将NPs包裹在沉积物中，同时与pH升高配合。然而，短期的生长促进在培养12天后导致细胞着色和缺磷。因此，光合-天线蛋白途径和能量代谢产物被下调，而磷酸盐和钙信号通路的跨膜转运和受体活性被上调以维持生长，在1 mg/L组达到平衡。类固醇生物合成的显著上调促进了质膜的疏水性，降低了水溶性离子的通透性，加剧了缺磷。卡尔文循环的下调改变了总碳代谢和碳迁移，减少了光合作用和呼吸作用，但积累了淀粉来抵消细胞遮荫和缺磷。这些发现为NPs对海洋微藻的短期生长刺激和长期潜在毒性作用的机制提供了新的见解，从而改变了海洋碳和磷循环。

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.