多形汉逊酵母代谢改造生产脂肪酸及发酵条件优化

Production of fatty acids by engineered Ogataea polymorpha

摘要:

脂肪酸作为一种化工原料，在生物能源、化妆品、个人护理产品和工业润滑剂等领域具有广泛应用。多形汉逊酵母因其能够利用甲醇、耐高温、底物谱广等优点，被认为是微生物细胞工厂的理想底盘宿主。本研究首先通过代谢工程构建了产脂肪酸的汉逊酵母细胞工厂。在此基础上，通过发酵条件优化进一步提升了工程菌株生产性能。在温度37℃、pH 6.4、培养基碳氮摩尔比为120、种子液OD₆₀₀在6–8之间时，摇瓶中工程菌脂肪酸产量达到1.86 g/L。在发酵罐中，采用溶氧（DO）关联法控制补料速度，初始培养基碳氮摩尔比为17.5，在DO高于30%时，补料碳氮摩尔比为120的葡萄糖培养基，脂肪酸产量达到18.0 g/L，显示了汉逊酵母作为脂肪酸合成细胞工厂的潜力，为实现工业化奠定了坚实的理论与应用基础。

关键词:多形汉逊酵母;代谢工程;脂肪酸;限氮发酵;发酵条件优化

Abstract:

Fatty acids (FA) are widely used as feed stocks for the production of cosmetics, personal hygiene products, lubricants and biofuels. Ogataea polymorpha is considered as an ideal chassis for bio-manufacturing, due to its outstanding characteristics such as methylotroph, thermal-tolerance and wide substrate spectrum. In this study, we harnessed O. polymorpha for overproduction of fatty acids by engineering its fatty acid metabolism and optimizing the fermentation process. The engineered strain produced 1.86 g/L FAs under the optimized shake-flask conditions (37℃, pH 6.4, a C/N ratio of 120 and an OD₆₀₀ of seed culture of 6-8). The fed-batch fermentation process was further optimized by using a dissolved oxygen (DO) control strategy. The C/N ratio of initial medium was 17.5, and the glucose medium with a C/N ratio of 120 was fed when the DO was higher than 30%. This operation resulted in a titer of 18.0 g/L FA, indicating the potential of using O. polymorpha as an efficient cell factory for the production of FA.

Key words:Ogataea polymorpha;metabolic engineering;fatty acids;nitrogen limitation;process optimization