Astaxanthin is a kind of carotenoid with a high antioxidant capacity, which has promising applications in feed and human health. As consumers demand more natural products, the biological production of astaxanthin has gained great attention. In this study, an astaxanthin producing Xanthophyllomyces dendrorhous strain DW6 was first isolated, whose astaxanthin synthetic pathway was determined by whole genome sequencing. Furthermore, fermentation parameters including temperature, pH and carbon and nitrogen sources used for the yeast growth and astaxanthin synthesis were also comprehensively investigated. Accordingly, a two-stage pH fermentation strategy was developed to relieve the metabolic stress and promote the astaxanthin accumulation. Transcriptome analysis found that the key genes of fada (encoding acetyl-CoA acyltransferase) for fatty acid degradation and GGPS1 (geranylgeranyl diphosphate synthase) for astaxanthin synthesis, as well as genes involved in the glutathione and peroxisome metabolism played major roles in the improved astaxanthin synthesis used in the two-stage pH process. Finally, an inferior substrate of sugarcane molasses was used as the sole carbon and nitrogen source, and 374.3 mg L⁻¹ of astaxanthin was produced with an astaxanthin content of 9.0 mg g⁻¹, representing the highest astaxanthin production from organic wastes by using X. dendrorhous. Overall, this study will pave the way for the large scale production of astaxanthin.

中文翻译：

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使用两阶段 pH 策略从甘蔗糖蜜中获得高产虾青素

虾青素是一种具有高抗氧化能力的类胡萝卜素，在饲料和人类健康方面具有广阔的应用前景。随着消费者对天然产品的需求越来越高，虾青素的生物生产受到了极大的关注。本研究首次分离出一株产虾青素的树状叶黄酵母菌株DW6，并通过全基因组测序确定了其虾青素合成途径。此外，还对酵母生长和虾青素合成所用的温度、pH、碳源和氮源等发酵参数进行了全面研究。因此，开发了两阶段pH发酵策略来缓解代谢应激并促进虾青素的积累。转录组分析发现，用于脂肪酸降解的fada （编码乙酰辅酶A酰基转移酶）和用于虾青素合成的GGPS1（香叶基香叶基二磷酸合酶）的关键基因，以及参与谷胱甘肽和过氧化物酶体代谢的基因在改善虾青素合成中发挥了重要作用用于两阶段 pH 过程。最后，以劣质甘蔗糖蜜为唯一碳源和氮源，生产了374.3 mg L ^-1的虾青素，虾青素含量为9.0 mg g ^-1，是利用X有机废物生产虾青素的最高产量。 . 树状的. 总的来说，这项研究将为虾青素的大规模生产铺平道路。