The present study was aimed to assess the effect of gibberellic acids to enhance the growth, biomass, pigment, and exopolysaccharides production in Tetraselmis suecica under reciprocal nitrogen concentrations. For this study, the seven types of experimental media (N-P, NL-P/2GA3, N0-P/2GA3, NL-P/4GA3, N0-P/4GA3, NL-P/6GA3, and N0-P/6GA3) were prepared with the addition of gibberellic acids under various nitrogen concentrations. The experiment lasted for 15 days and the cell density, biomass, chlorophyll 'a', and exopolysaccharides (EPS) concentration of T. suecica were estimated for every 3 days. Then the EPS was subjected to the analyses of chemical (carbohydrate, protein, sulfate, and uronic acid), and antioxidant activity. In addition, nutrient removal efficiency was evaluated using different concentration of EPS. The highest DPPH (2,2-diphenyl-1-picrylhydrazyl) (86.7 ± 0.95%) and hydroxyl radical activity (85.7 ± 2.48%) were observed at the EPS concentrations 2.5 and 1.2 mg/mL, respectively. The immobilized magnetic Fe3O4-EPS (ferric oxide-exopolysaccharides) nanoparticles (5.0 and 10.0 g/L) have efficiently removed the excessive phosphate (89.5 ± 1.65%) and nitrate (73.5 ± 1.72%) from the Litopenaeus vannamei cultured wastewater. Thus, the application of gibberellic acids combined with limited nitrogen concentration could produce higher EPS that could exhibit excellent antioxidant activity, and nutrient removal efficacy in the form of Fe3O4-EPS magnetic nanoparticles.

中文翻译：

---

赤霉酸在氮浓度倒数下促进 Tetraselmis suecica 的生长和胞外多糖的产生：固定化铁磁纳米粒子的抗氧化特性和营养去除功效的评估。

本研究旨在评估赤霉酸在氮浓度倒数下对 Tetraselmis suecica 的生长、生物量、色素和胞外多糖生产的影响。对于这项研究，七种类型的实验介质（NP、NL-P/2GA3、N0-P/2GA3、NL-P/4GA3、N0-P/4GA3、NL-P/6GA3 和 N0-P/6GA3）是通过在不同氮浓度下添加赤霉酸制备的。实验持续 15 天，每 3 天估计一次 T. suecica 的细胞密度、生物量、叶绿素 'a' 和胞外多糖 (EPS) 浓度。然后对 EPS 进行化学（碳水化合物、蛋白质、硫酸盐和糖醛酸）和抗氧化活性分析。此外，使用不同浓度的 EPS 评估了养分去除效率。最高DPPH（2，在 EPS 浓度分别为 2.5 和 1.2 mg/mL 时，观察到 2-二苯基-1-苦基肼基 (86.7 ± 0.95%) 和羟基自由基活性 (85.7 ± 2.48%)。固定化磁性 Fe3O4-EPS（氧化铁-胞外多糖）纳米颗粒（5.0 和 10.0 g/L）有效去除了凡纳滨对虾养殖废水中过量的磷酸盐 (89.5 ± 1.65%) 和硝酸盐 (73.5 ± 1.72%)。因此，赤霉酸的应用结合有限的氮浓度可以产生更高的 EPS，表现出优异的抗氧化活性，以及​​ Fe3O4-EPS 磁性纳米粒子形式的营养去除功效。固定化磁性 Fe3O4-EPS（氧化铁-胞外多糖）纳米颗粒（5.0 和 10.0 g/L）有效去除了凡纳滨对虾养殖废水中过量的磷酸盐 (89.5 ± 1.65%) 和硝酸盐 (73.5 ± 1.72%)。因此，赤霉酸的应用结合有限的氮浓度可以产生更高的 EPS，表现出优异的抗氧化活性，以及​​ Fe3O4-EPS 磁性纳米粒子形式的营养去除功效。固定化磁性 Fe3O4-EPS（氧化铁-胞外多糖）纳米颗粒（5.0 和 10.0 g/L）有效去除了凡纳滨对虾养殖废水中过量的磷酸盐 (89.5 ± 1.65%) 和硝酸盐 (73.5 ± 1.72%)。因此，赤霉酸的应用结合有限的氮浓度可以产生更高的 EPS，表现出优异的抗氧化活性，以及​​ Fe3O4-EPS 磁性纳米粒子形式的营养去除功效。