LB3 - Faculty of Science and Engineering, University of Madeira, 9000-390, Funchal, Portugal.
Mariculture Center of Calheta, Fisheries Directorate, 9370-133, Calheta, Portugal; CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, 4450-208, Matosinhos, Portugal.
Environ Pollut. 2019 Jun;249:372-380. doi: 10.1016/j.envpol.2019.03.046. Epub 2019 Mar 18.
Microalgae can excrete exopolymer substances (EPS) with a potential to form hetero-aggregates with microplastic particles. In this work, two freshwater (Microcystis panniformis and Scenedesmus sp.) and two marine (Tetraselmis sp. and Gloeocapsa sp.) EPS producing microalgae were exposed to different microplastics. In this study, the influence of the microplastic particles type, size and density in the production of EPS and hetero-aggregates potential was studied. Most microalgae contaminated with microplastics displayed a cell abundance decrease (of up to 42%) in the cultures. The results showed that the formed aggregates were composed of microalgae and EPS (homo-aggregates) or a combination of microalgae, EPS and microplastics (hetero-aggregates). The hetero-aggregation was dependent on the size and yield production of EPS, which was species specific. Microcystis panniformis and Scenedesmus sp. exhibited small EPS, with a higher propension to disaggregate, and consequently lower capabilities to aggregate microplastics. Tetraselmis sp. displayed a higher ability to aggregate both low and high-density microplastics, being partially limited by the size of the microplastics. Gloeocapsa sp. had an outstanding EPS production and presented excellent microplastic aggregation capabilities (adhered onto the surface and also incorporated into the EPS). The results highlight the potential of microalgae to produce EPS and flocculate microplastics, contributing to their vertical transport and consequent deposition. Thus, this work shows the potential of microalgae as biocompatible solutions to water microplastics treatment.
微藻可以分泌具有与微塑料颗粒形成异质聚集潜力的胞外聚合物物质 (EPS)。在这项工作中，两种淡水（微囊藻和栅藻）和两种海洋（塔胞藻和胶球藻）产 EPS 的微藻暴露于不同的微塑料中。在这项研究中，研究了微塑料颗粒类型、大小和密度对 EPS 产生和异质聚集潜力的影响。大多数被微塑料污染的微藻在培养物中的细胞丰度下降（高达 42%）。结果表明，形成的聚集体由微藻和 EPS（同聚体）或微藻、EPS 和微塑料的组合（异聚体）组成。异聚是由 EPS 的大小和产量决定的，这是特定于物种的。微囊藻和栅藻表现出较小的 EPS，更容易解聚，因此聚集微塑料的能力较低。塔胞藻显示出更高的能力来聚集低密度和高密度的微塑料，部分受到微塑料尺寸的限制。胶球藻具有出色的 EPS 生产能力，并具有出色的微塑料聚集能力（附着在表面上，也被纳入 EPS 中）。结果强调了微藻产生 EPS 和絮凝微塑料的潜力，有助于它们的垂直运输和随后的沉积。因此，这项工作展示了微藻作为水微塑料处理的生物相容性解决方案的潜力。
