Zhu Yuan, Yan Xiaoguang, Li Weiguo, Qiao Jianjun, Zhao Guang-Rong
State Key Laboratory of Synthetic Biology, School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, China.
Georgia Tech Shenzhen Institute, Tianjin University, Dashi Road 1, Nanshan District, Shenzhen 518055, PR of China.
J Agric Food Chem. 2025 Feb 12;73(6):3580-3590. doi: 10.1021/acs.jafc.4c09840. Epub 2025 Jan 30.
Ursolic acid, a plant-derived pentacyclic triterpenoid with anti-inflammatory, antioxidant, and other bioactive properties, holds significant potential for use in nutritional supplements and drug development. However, its extraction from medicinal plants is inefficient due to low yield and dependence on seasonality and geography. Herein, we use modular metabolic engineering to enhance ursolic acid production in by dividing the biosynthetic pathway into five modules. First, the heterologous ursolic acid biosynthesis module was established using α-amyrin synthase () and a fused α-amyrin oxidase () with cytochrome P450 reductase (CPR). Next, the full hybrid mevalonate pathway was overexpressed, and the copy number of was optimized. The sterol pathway was further optimized by introducing N-degron tags to relieve the competition pathway and deleting the gene to enhance the stability. Acetyl-CoA supply was improved via phosphoketolase and acetyl-CoA synthase pathways, combined with fine-tuning of mitochondrial and cytosolic carbon flux. The final engineered strain produced 1083.62 mg/L of ursolic acid in shake-flask cultures and 8.59 g/L in a 5 L bioreactor via fed-batch fermentation, achieving the highest microbial ursolic acid titer reported to date. This study not only demonstrates the potential for efficient biosynthesis of triterpenoid compounds but also provides ideas that can be extended to other microbial hosts for the concentrated use of intracellular carbon sources in the synthesis of complex natural products.
熊果酸是一种源自植物的五环三萜类化合物，具有抗炎、抗氧化和其他生物活性特性，在营养补充剂和药物开发方面具有巨大的应用潜力。然而，由于其产量低以及对季节性和地理条件的依赖，从药用植物中提取熊果酸的效率较低。在此，我们利用模块化代谢工程通过将生物合成途径分为五个模块来提高熊果酸在[具体生物，原文未提及]中的产量。首先，使用α-香树脂醇合酶（[具体酶名称，原文未提及]）和与细胞色素P450还原酶（CPR）融合的α-香树脂醇氧化酶（[具体酶名称，原文未提及]）建立了异源熊果酸生物合成模块。接下来，过表达完整的杂交甲羟戊酸途径，并优化了[具体基因，原文未提及]的拷贝数。通过引入N-降解决定子标签以缓解竞争途径并删除[具体基因，原文未提及]基因来增强[具体物质，原文未提及]的稳定性，从而进一步优化了甾醇途径。通过磷酸酮醇酶和乙酰辅酶A合酶途径改善了乙酰辅酶A的供应，并结合线粒体和胞质碳通量的微调。最终的工程菌株在摇瓶培养中产生了1083.62 mg/L的熊果酸，在5 L生物反应器中通过补料分批发酵产生了8.59 g/L的熊果酸，达到了迄今为止报道的最高微生物熊果酸滴度。这项研究不仅证明了三萜类化合物高效生物合成的潜力，还提供了可扩展到其他微生物宿主以在复杂天然产物合成中集中利用细胞内碳源的思路。
