Abstract Dark fermentation is an anaerobic digestion process of biowaste, used to produce hydrogen as a fuel, which however releases high amounts of polluting volatile fatty acids in the environment. In order for the process to become more competitive, the acids stream can be utilized through conversion to high added-value docosahexaenoic acid by the microalga Crypthecodinium cohnii. Docosahexaenoic acid is one of the two main omega-3 fatty acids, necessary for human nutrition. The purpose of this work was to optimize the production of omega-3 fatty acids by the cells, utilizing the organic content of a dark fermentation effluent. For that purpose, the effect of different fermentation conditions was examined, such as incubation temperature, nitrogen source and concentration, the addition of chemical modulators, as well as the feeding composition. The volatile fatty acid content of the effluent was totally depleted in a fed-batch culture of the microalga, while the cells accumulated DHA in a percentage of 35.6% of total lipids, when fed with yeast extract or 34.2% when fed with ammonium sulfate. Taking into consideration the economic feasibility of the culture conditions proposed it was concluded that the use of yeast extract could be substituted by the much economic ammonium sulfate.

中文翻译：

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利用暗发酵出水优化异养微藻Crypthecodinium cohnii生产二十二碳六烯脂肪酸

摘要 暗发酵是生物废物的厌氧消化过程，用于生产氢气作为燃料，但会在环境中释放大量污染性的挥发性脂肪酸。为了使该过程更具竞争力，可以通过微藻 Crypthecodinium cohnii 将酸流转化为高附加值的二十二碳六烯酸来利用。二十二碳六烯酸是两种主要的 omega-3 脂肪酸之一，是人类营养所必需的。这项工作的目的是利用黑暗发酵流出物中的有机成分，优化细胞对 omega-3 脂肪酸的生产。为此，检查了不同发酵条件的影响，例如孵育温度、氮源和浓度、化学调节剂的添加以及饲养成分。在微藻的分批补料培养中，流出物中的挥发性脂肪酸含量完全耗尽，而细胞积累的 DHA 占总脂质的 35.6%，当用酵母提取物喂养时，或用硫酸铵喂养时为 34.2%。考虑到所提出的培养条件的经济可行性，得出的结论是酵母提取物的使用可以被更经济的硫酸铵替代。