透明质酸是一种被广泛应用于医药、化妆品和食品等领域的糖胺聚糖。透明质酸的主要工业生产菌株为兽疫链球菌,由于该细菌具有致病性,因此迫切需要构建安全的透明质酸生产菌株。通过在食品级表达宿主谷氨酸棒杆菌中异源表达透明质酸合酶基因(pmHasA),实现了透明质酸的合成,摇瓶中产量达到0.35 g/L。通过强化代谢途径中尿苷二磷酸-葡萄糖脱氢酶基因(ugdA2)和磷酸氨基转移酶基因(glmS)的表达以及敲除乳酸脱氢酶基因(ldh),透明质酸产量提高至0.81 g/L。在此基础上优化诱导条件,确定异丙基-β-D硫代半乳糖苷浓度为0.8 mmol/L,诱导剂添加时间为2 h时,摇瓶中透明质酸产量最高达到1 g/L。经过3 L发酵罐分批补料发酵,透明质酸产量达到4.8 g/L。该文通过调控谷氨酸棒杆菌代谢途径实现了透明质酸安全、高效的合成,为食品级透明质酸的生产奠定了基础。
Hyaluronic acid is a glycosaminoglycan widely used in medicine, cosmetics and food industries. The main industrial production strain of hyaluronic acid is Streptococcus zooepidemicus. Because the bacteria are pathogenic, there is an urgent need to construct a safe hyaluronic acid producing strain. By heterologous expression of hyaluronic acid synthase (pmHasA) in a food-grade expression host, Corynebacterium glutamicum, the synthesis of current hyaluronic acid was achieved, and the yield in shake flasks reached 0.35 g/L. By enhancing the expression of the UDP-glucose dehydrogenase gene (ugdA2) and phosphoaminotransferase gene (glmS) in the metabolic pathway and knocking out the lactate dehydrogenase gene (ldh), the yield of hyaluronic acid increased to 0.81 g/L. Based on this, the induction conditions were optimized, and the optimal isopropyl-β-D-thiogalactopyranoside (IPTG) concentration was determined to be 0.8 mmol/L, and the induction time was 2 hours. Under these conditions, the highest yield of hyaluronic acid in shake flask was 1 g/L. After batch fed fermentation in a 3 L fermenter, the hyaluronic acid yield reached 4.8 g/L. In this paper, the safe and efficient synthesis of hyaluronic acid was achieved by regulating the metabolic pathway of Corynebacterium glutamicum, which laid the foundation for the production of food-grade hyaluronic acid.
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