乙醇酸高产菌株的筛选及发酵

Screening and fermentation of high-yield glycolic acid strains

摘要:

乙醇酸是一种重要的化工产品，广泛应用于化妆品、清洁剂及纺织品等各个领域。目前，微生物法生产乙醇酸存在菌株遗传稳定性差、产率低、成本高的缺点，而全细胞催化生产乙醇酸大多需要添加价格相对昂贵的山梨醇作为碳源，限制了其工业化生产。为了开发一种适用于工业化应用的乙醇酸生产方法，本研究以乙二醇为底物进行全细胞催化筛选乙醇酸生产菌株，获得了一株产乙醇酸的红酵母。随后对该菌株进行了紫外诱变，并通过高通量筛选得到了正突变株RMGly-20，摇瓶优化后该菌株的乙醇酸产量为17.8 g/L，比原始菌株提高了10.1倍。以葡萄糖为碳源，经5 L发酵罐补料分批培养，菌株RMGly-20可生产61.1 g/L乙醇酸，初步实现了可利用廉价碳源且遗传稳定的乙醇酸菌株的选育，为生物法合成乙醇酸提供了新宿主，有利于进一步推进乙醇酸的工业化生产。

关键词:乙醇酸;红酵母;乙二醇;紫外诱变;高通量筛选

Abstract:

Glycolic acid is an important chemical product widely used in various fields, including cosmetics, detergents, textiles, and more. Currently, microbial production of glycolic acid has disadvantages such as poor genetic stability, low yield, and high cost. Additionally, whole-cell catalytic production of glycolic acid typically requires the addition of relatively expensive sorbitol as a carbon source, which limits its industrial production. To develop an industrially applicable method for glycolic acid production, this study used ethylene glycol as a substrate to screen the glycolic acid-producing strains through whole-cell catalysis, obtaining a Rhodotorula sp. capable of producing glycolic acid. The strain was then subjected to UV mutagenesis and high throughput screening, and the positive mutant strain RMGly-20 was obtained. After optimization in shake flasks, the glycolic acid titer of RMGly-20 reached 17.8 g/L, a 10.1-fold increase compared to the original strain. Using glucose as the carbon source and employing a fed-batch culture in a 5 L fermenter, strain RMGly-20 produced 61.1 g/L of the glycolic acid. This achievement marks the preliminary breeding of a genetically stable glycolic acid-producing strain using a cheap carbon source, providing a new host for the biosynthesis of glycolic acid and promoting further progress toward industrial production.

Key words:glycolic acid;Rhodotorula sp.;ethylene glycol;UV mutagenesis;high throughput screening