The microalgal strain Scenedesmus rubescens KNUA042 was identified in freshwater in Korea and characterized by evaluating its stress responses in an effort to increase lipid and carotenoid production. Under a two-stage cultivation process, the algal strain that generally exhibits optimal growth at a nitrate (source of nitrogen) concentration of 0.25 g L −1 was challenged to different exogenous stimuli—salinity (S), light intensity (L), combined L and S (LS), and nitrogen deficiency (C)—for 14 days. Lipid production and carotenoid concentration increased in a time-dependent manner under these physicochemical conditions during the culture periods. Lipid accumulation was confirmed by thin layer chromatography, BODIPY staining, and fatty acid composition analysis, which showed no differences in the algal cells tested under all four (C, S, L, and LS) conditions. The quality of biodiesel produced from the biomass of the algal cells met the American Society for Testing and Materials and the European standards. Total carotenoid content was increased in the LS-treated algal cells (6.94 mg L −1 ) compared with that in the C-, S-, and L-treated algal cells 1.75, 4.15, and 1.32 mg L −1 , respectively). Accordingly, the concentration of canthaxanthin and astaxanthin was also maximized in the LS-treated algal cells at 1.73 and 1.11 mg g −1 , respectively, whereas lutein showed no differences in the cells analyzed. Conversely, chlorophyll a level was similar among the C-, S-, and LS-treated algal cells, except for the L-treated algal cells. Thus, our results suggested that S . rubescens KNUA042 was capable of producing carotenoid molecules, which led to the maximum values of canthaxanthin and astaxanthin concentrations when exposed to the combined LS condition compared with that observed when exposed to the salinity condition alone. This indicates that the algal strain could be used for the production of high-value products as well as biofuel. Furthermore, this article provides the first evidence of carotenoid production in S . rubescens KNUA042.

中文翻译：

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氮缺乏相关的非生物胁迫增强了本土绿色微藻栅栏藻 KNUA042 中类胡萝卜素的产生，用作高价值产品的潜在资源

微藻菌株 Scenedesmus rubescens KNUA042 在韩国的淡水中被鉴定出来，其特征是评估其应激反应以努力增加脂质和类胡萝卜素的产生。在两阶段培养过程中，通常在 0.25 g L -1 的硝酸盐（氮源）浓度下表现出最佳生长的藻类菌株受到不同外源刺激的挑战——盐度 (S)、光强度 (L)、组合L 和 S (LS)，以及缺氮 (C) — 14 天。在培养期间，在这些物理化学条件下，脂质产生和类胡萝卜素浓度以时间依赖性方式增加。通过薄层色谱法、BODIPY 染色和脂肪酸组成分析证实了脂质积累，这表明在所有四种（C、S、L、和 LS) 条件。由藻类细胞的生物质生产的生物柴油的质量符合美国材料试验协会和欧洲标准。与C-、S-和L-处理的藻细胞中的总类胡萝卜素含量相比，LS-处理的藻细胞(6.94 mg L -1 )中的总类胡萝卜素含量分别增加了1.75、4.15和1.32 mg L -1 )。因此，LS 处理的藻细胞中角黄素和虾青素的浓度也分别为 1.73 和 1.11 mg g -1 ，而叶黄素在所分析的细胞中没有显示出差异。相反，除了 L 处理的藻类细胞外，C-、S- 和 LS 处理的藻类细胞的叶绿素 a 水平相似。因此，我们的结果表明 S 。rubescens KNUA042 能够产生类胡萝卜素分子，与单独暴露于盐度条件时观察到的相比，这导致暴露于组合 LS 条件时角黄素和虾青素浓度的最大值。这表明藻类菌株可用于生产高价值产品以及生物燃料。此外，本文提供了 S 中产生类胡萝卜素的第一个证据。冬凌草 KNUA042。