微藻生物膜有望同时去除污染物,CO2固定,废水作为培养基时的生物质资源转化。一氧化氮(NO)通常在废水处理相关的非生物胁迫如氮缺乏下积累在微藻细胞中,重金属,和抗生素。然而,新出现的污染物如微塑料(MPs)对微藻细胞内NO的影响仍然未知。此外,在现有研究中,所调查的MP浓度大多比实际废水高几个数量级,这可以为环境相关浓度下MP对微藻的影响提供有限的指导。因此,这项研究调查了与环境相关的浓度(10-10,000μg/L)的废水中三种常见的MP,并探讨了它们对附着的小球藻的影响。生长特性,营养素去除,和抗氧化反应(包括细胞内NO含量)。由于细胞内NO积累最少,因此选择49mg/L的氮源NO3--N为经典BG-11培养基中氮强度的20%用于MPs暴露实验。这样就可以避免氮利用率对细胞内NO的干扰。在这种情况下,与聚氯乙烯(PVC)和聚酰胺(PA)MPs相比,10μg/L聚乙烯(PE)MPs表现出最显著的微藻生长抑制作用,表现出极低的叶绿素a/b比,MPs暴露12天后,超氧化物歧化酶(SOD)活性和细胞内NO含量最高。由于有机氯的毒性特征,暴露于PVCMPs的培养物显示出最高的丙二醛(MDA)含量,细胞内NO含量与常规SOD抗氧化指标的相关性最显著,CAT(过氧化氢酶),和MDA。MPs加速除磷,国会议员的类型而不是浓度表现出更高的影响,遵循PE>PA>PVC的趋势。这项研究扩大了在环境相关浓度的MPs下微藻生物膜的知识,并创新性地发现了MPs暴露下细胞内NO作为比常规抗氧化参数更敏感的指标的意义。
Microalgal biofilm is promising in simultaneous pollutants removal, CO2 fixation, and biomass resource transformation when wastewater is used as culturing medium. Nitric oxide (NO) often accumulates in microalgal cells under wastewater treatment relevant abiotic stresses such as nitrogen deficiency, heavy metals, and antibiotics. However, the influence of emerging contaminants such as microplastics (MPs) on microalgal intracellular NO is still unknown. Moreover, the investigated MPs concentrations among existing studies were mostly several magnitudes higher than in real wastewaters, which could offer limited guidance for the effects of MPs on microalgae at environment-relevant concentrations. Therefore, this study investigated three commonly observed MPs in wastewater at environment-relevant concentrations (10-10,000 μg/L) and explored their impacts on attached Chlorella sp. growth characteristics, nutrients removal, and anti-oxidative responses (including intracellular NO content). The nitrogen source NO3--N at 49 mg/L being 20 % of the nitrogen strength in classic BG-11 medium was selected for MPs exposure experiments because of least intracellular NO accumulation, so that disturbance of intracellular NO by nitrogen availability could be avoided. Under such condition, 10 μg/L polyethylene (PE) MPs displayed most significant microalgal growth inhibition comparing with polyvinyl chloride (PVC) and polyamide (PA) MPs, showing extraordinarily low chlorophyll a/b ratios, and highest superoxide dismutase (SOD) activity and intracellular NO content after 12 days of MPs exposure. PVC MPs exposed cultures displayed highest malonaldehyde (MDA) content because of the toxic characteristics of organochlorines, and most significant correlations of intracellular NO content with conventional anti-oxidative parameters of SOD, CAT (catalase), and MDA. MPs accelerated phosphorus removal, and the type rather than concentration of MPs displayed higher influences, following the trend of PE > PA > PVC. This study expanded the knowledge of microalgal biofilm under environment-relevant concentrations of MPs, and innovatively discovered the significance of intracellular NO as a more sensitive indicator than conventional anti-oxidative parameters under MPs exposure.