Microalgal extracellular polymeric substances (EPSs) are heteropolysaccharides that have characteristics suitable for industrial and biotechnological applications. Notably, they have strong anionic nature and high hydrophobicity. Nevertheless, systematic studies to demonstrate the viability of the production of EPSs on an industrial scale are still crucial. In this research, the chlorophyte Graesiella was grown on a raceway pond to view its EPS valorization. The biomass production achieved a maximum of 1.98 g L⁻¹ and an EPS production of 1.6 g L⁻¹ after six production days. The Graesiella EPSs with a molecular weight above 100 kDa are sulfated exopolymers containing mainly polysaccharide (70%) and protein (16%). The EPSs produced more stable emulsions with hydrocarbons and oils than Tween-20. The emulsification indices with n-hexane (88%) and maize oil (28%) indicate the EPSs’ strong emulsion-stabilizing capacity. The EPSs showed a peak flocculating percentage of 95% to kaolin suspension, with better flocculation performance than Al₂(SO₄)₃ and alginate. Moreover, Graesiella EPSs had a significant effect on antimicrobial activity, significantly inhibiting fungal growth (71% for Botytis cinerea and 87% for Fusarium oxysporum), spore germination (100% of inhibition at a concentration of 1.8 g L⁻¹), and mycelium growth (68% of inhibition). Also, Graesiella EPSs acted as a bactericide against Vibrio anguilaruim and Listonella anguilaruim (100% inhibition). EPSs were also found to have potent antioxidant activity compared with l-ascorbic acid. The obtained results open new perspectives to the further exploration of Graesiella sp. as a potential EPS producer, making it a promising candidate for numerous industrial applications.

微藻胞外聚合物（EPS）是杂多糖，具有适合工业和生物技术应用的特性。值得注意的是，它们具有强的阴离子性质和高的疏水性。然而，进行系统研究以证明工业规模生产EPS的可行性仍然至关重要。在这项研究中，绿藻Graesiella生长在跑道池上，以观察其EPS增值。六天的生产后，生物量的最高产量达到1.98 g L ^-1，EPS产量达到1.6 g L ^-1。该Graesiella分子量高于100 kDa的EPS是主要包含多糖（70％）和蛋白质（16％）的硫酸化的外聚物。与Tween-20相比，EPS产生的含烃和油的乳液更稳定。与乳化指数Ñ己烷（88％）和玉米油（28％）表明起初只是强乳液稳定的能力。EPSs对高岭土悬浮液的峰值絮凝率为95％，比Al ₂（SO ₄）₃和藻酸盐具有更好的絮凝性能。此外，Graesiella EPS对抗菌活性有显着影响，显着抑制了真菌的生长（灰葡萄孢（Botytis cinerea）为71 ％，尖孢镰刀菌（Fusarium oxysporum）为87％），孢子萌发（在1.8 g L ^-1的浓度下抑制100％）和菌丝生长（抑制的68％）。另外，Graesiella EPS充当抗弧菌和安氏李斯特菌的杀菌剂（100％抑制）。与1-抗坏血酸相比，EPS也被发现具有有效的抗氧化活性。获得的结果为进一步探索Graesiella sp。开辟了新的前景。作为潜在的EPS生产商，使其成为众多工业应用的有希望的候选者。