School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China.
Pan Asia (Jiangmen) Institute of Biological Engineering and Health, Jiangmen, 529080, China.
Appl Microbiol Biotechnol. 2021 Sep;105(18):6691-6706. doi: 10.1007/s00253-021-11512-7. Epub 2021 Aug 31.
Natural water-soluble Monascus pigments (WSMPs) have been in increasing demand but have not been able to achieve industrial production due to the low production rate. This study aimed to improve the biosynthesis and secretion of extracellular yellow pigments (EYPs) through submerged fermentation with Monascus ruber CGMCC 10,910 supplemented with sodium starch octenyl succinate (OSA-SNa). The results demonstrated that the yield was 69.68% and 48.89% higher than that without OSA-SNa in conventional fermentation (CF) and extractive fermentation (EF), respectively. The mainly increased EYP components were Y3 and Y4 in CF, but they were mainly Y1 and Y2 as well as secreted intracellular pigments, including Y5, Y6, O1, and O2, in EF. Scanning electron microscopy analysis revealed that the mycelium presented an uneven surface profile with obvious wrinkles and small fragments with OSA-SNa. It was found that a higher unsaturated/saturated fatty acids ratio in the cell membrane resulted in increased permeability and facilitated the export of intracellular yellow pigments into the broth with OSA-SNa treatment. In addition, a higher NAD/NADH ratio and glucose-6-phosphate dehydrogenase activity provided a reducing condition for yellow pigment biosynthesis. Gene expression analysis showed that the expression levels of the key genes for yellow pigment biosynthesis were significantly upregulated by OSA-SNa. This study provides an effective strategy to promote the production of WSMPs by microparticle-enhanced cultivation using OSA-SNa. KEY POINTS: • OSA-SNa addition facilitated the production of Monascus yellow pigments. • Mycelial morphology and membrane permeability were affected by OSA-SNa. • The key gene expression of yellow pigments was upregulated.
天然水溶性红曲米色素（WSMPs）的需求不断增加，但由于产率低，一直未能实现工业化生产。本研究旨在通过添加辛烯基琥珀酸淀粉钠（OSA-SNa）的红曲霉 CGMCC 10,910 进行深层发酵，提高胞外黄色素（EYPs）的生物合成和分泌。结果表明，与传统发酵（CF）和提取发酵（EF）相比，添加 OSA-SNa 分别使产量提高了 69.68%和 48.89%。CF 中主要增加的 EYP 组分为 Y3 和 Y4，但 EF 中主要增加的是 Y1 和 Y2 以及分泌的胞内色素，包括 Y5、Y6、O1 和 O2。扫描电子显微镜分析表明，添加 OSA-SNa 后，菌丝体表面呈现不均匀的形态，出现明显的褶皱和小碎片。研究发现，细胞膜中不饱和/饱和脂肪酸的比例升高，导致细胞膜的通透性增加，有利于胞内黄色素向发酵液中的输出。此外，较高的 NAD/NADH 比值和葡萄糖-6-磷酸脱氢酶活性为黄色素生物合成提供了还原条件。基因表达分析表明，OSA-SNa 显著上调了黄色素生物合成的关键基因的表达水平。本研究为利用 OSA-SNa 进行微粒增强培养促进 WSMPs 生产提供了一种有效的策略。 关键点： • 添加 OSA-SNa 促进了红曲黄色素的生产。 • OSA-SNa 影响了菌丝体形态和膜通透性。 • 黄色素的关键基因表达上调。
