State Key Laboratory of Food Science and Technology, Nanchang University, No. 235 Nanjing East Road, Nanchang 330047, China; Sino-German Joint Research Institute, Nanchang University, No. 235 Nanjing East Road, Nanchang 330047, China.
State Key Laboratory of Food Science and Technology, Nanchang University, No. 235 Nanjing East Road, Nanchang 330047, China.
Food Res Int. 2022 Oct;160:111700. doi: 10.1016/j.foodres.2022.111700. Epub 2022 Jul 19.
Exopolysaccharides (EPS), metabolites of the medicinal edible fungus Monascus purpureus, have antioxidant, immunomodulatory, and anti-inflammatory effects. However, the biosynthetic mechanism of EPS from M. purpureus is still unclear, which hinders its utilization. In this study, the fermentation conditions of M. purpureus were optimized and comparative transcriptomic analysis was performed to understand the mechanisms and effects of fermentation on EPS synthesis. The optimal medium composition was 40 g/L mannose, 4 g/L yeast powder, 1 g/L MgSO·7HO, 0.8 g/L KHPO, 1.6 g/L KHPO·3HO, and 2 mL/L Tween 80, and the optimal cultivation conditions were an inoculum of 7 %, culture temperature 30 °C, initial pH 6.0, and 180 rpm for 4 d. A total of 8095 unigenes were obtained, and 17 key enzymes for EPS synthesis were identified. Interestingly, 12 carbohydrate metabolism subcategories were enriched in the group with 4 days of fermentation compared to 2 days, with most of the differentially expressed genes (DEGs) being upregulated, but only nine carbohydrate metabolism subcategories were enriched with longer fermentation time, with all DEGs being downregulated. This study provides a theoretical basis for enhancing the EPS content and reveals the dynamics of EPS synthesis in M. purpureus, providing important targets for future EPS molecular modifications and gene knockdown studies.
胞外多糖（EPS）是药用真菌红曲的代谢产物，具有抗氧化、免疫调节和抗炎作用。然而，红曲 EPS 的生物合成机制尚不清楚，这阻碍了其利用。在这项研究中，优化了红曲的发酵条件，并进行了比较转录组分析，以了解发酵对 EPS 合成的机制和影响。最佳培养基组成为 40g/L 甘露糖、4g/L 酵母粉、1g/L MgSO·7HO、0.8g/L KHPO、1.6g/L KHPO·3HO 和 2mL/L Tween 80，最佳培养条件为接种量 7%、培养温度 30°C、初始 pH6.0、180rpm 培养 4d。共获得 8095 个基因，鉴定出 17 种 EPS 合成关键酶。有趣的是，与 2 天发酵相比，发酵 4 天的组中 12 个碳水化合物代谢亚类富集，大多数差异表达基因（DEGs）上调，但随着发酵时间的延长，只有 9 个碳水化合物代谢亚类富集，所有 DEGs 下调。本研究为提高 EPS 含量提供了理论基础，并揭示了红曲中 EPS 合成的动态，为未来 EPS 分子修饰和基因敲低研究提供了重要目标。
