Abstract A novel integrated process from cultivation to enzyme-assisted extraction and ethanolysis of lipids was established and implemented to produce sustainable and clean microalgal biodiesel by three marine Nannochloropsis strains (N. oculata, Nannochloropsis sp. and N. oceanica). Among the selected strains, N. oculata was selected as a model for the evaluation of lipid extraction performance and biodiesel conversion, due to its highest biomass (4.38 g/L) and total fatty acids (TFAs) yield (1.55 g/L). In the lipid extraction, three phase partitioning (TPP) exhibited superior lipid extraction performance when N. oculata cells were treated by four mixed enzymes (cellulase, hemicellulase, papain and pectinase). After optimization, the highest FAMEs recovery (92.59%) was obtained by TPP at 1.5% microalgal biomass, 6% K2HPO4, 65% ethanol content, 80 °C extraction temperature, 1 h incubation time and two extraction cycles. In the enzymatic ethanolysis, the extracted lipids from the ethanol phase of TPP were directly used for biodiesel with liquid lipase from Thermomyces lanuginosus (TL) and results showed that lipase TL performed the greatest biodiesel conversion (90.24%) under the optimized conditions. Lastly, this integrated process was re-evaluated with two Nannochloropsis strains. Results showed that the integrated process attained 85.12% biodiesel conversion for Nannochloropsis sp. and 76.33% for N. oceanica, demonstrating that the lipidic class and fatty acid composition influenced the biodiesel conversion by enzymatic ethanolysis. Taken together, the integrated process mediated with enzymes and ethanol as green media was a promising strategy for cost-effective and low-value bulky biodiesel by oleaginous Nannochloropsis strains.

中文翻译：

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绿色微藻纳米绿藻的可持续生物柴油生产：从培养到酶辅助提取和脂质乙醇解的新型集成工艺

摘要 建立并实施了一种从培养到酶辅助提取和脂质乙醇分解的新型集成工艺，以通过三种海洋微绿藻菌株（N. oculata、Nannochloropsis sp. 和 N. oceanica）生产可持续和清洁的微藻生物柴油。在选定的菌株中，N. oculata 因其最高的生物量 (4.38 g/L) 和总脂肪酸 (TFA) 产量 (1.55 g/L) 被选为评估脂质提取性能和生物柴油转化率的模型。在脂质提取中，当 N. oculata 细胞用四种混合酶（纤维素酶、半纤维素酶、木瓜蛋白酶和果胶酶）处理时，三相分配 (TPP) 表现出优异的脂质提取性能。优化后，TPP 在 1.5% 微藻生物质、6% K2HPO4、65% 乙醇含量下获得最高 FAMEs 回收率（92.59%），80 °C 提取温度、1 小时孵育时间和两个提取循环。在酶促乙醇分解中，从 TPP 乙醇相中提取的脂质直接用于生物柴油和来自疏毛嗜热丝孢菌 (TL) 的液体脂肪酶，结果表明脂肪酶 TL 在优化条件下进行了最大的生物柴油转化率 (90.24%)。最后，用两种微绿球藻菌株重新评估了这一集成过程。结果表明，该集成工艺对 Nannochloropsis sp. 的生物柴油转化率达到了 85.12%。N. Oceanica 为 76.33%，表明脂质类别和脂肪酸组成影响了酶促乙醇分解的生物柴油转化。综合起来，