Chen Yaozong, Wan Zihua, Li Zheng-Jun
State Key Laboratory of Green Biomanufacturing, National Energy R&D Center for Biorefinery, and Beijing Key Laboratory of Green Chemicals Biomanufacturing, Beijing University of Chemical Technology, Beijing 100029, China.
Metabolites. 2025 Jun 18;15(6):410. doi: 10.3390/metabo15060410.
: Heparosan is a component of the capsular polysaccharide in K5 and Type D. It shares a similar glycan structure with heparin and can be enzymatically modified to produce bioactive heparin. : In this study, the probiotic strain Nissle 1917 (EcN), which naturally produces heparosan, was genetically engineered to utilize sucrose as a carbon source for growth while achieving high-yield heparosan biosynthesis. : By expressing the sucrose hydrolase genes (from ) or (from ), EcN was enabled to utilize sucrose, achieving heparosan titers of 131 mg/L and 179 mg/L, respectively. Further metabolic engineering was performed to block the glycolytic and pentose phosphate pathways, thereby redirecting sucrose-derived glucose-6-phosphate and fructose-6-phosphate toward heparosan biosynthesis, while glycerol was supplemented as an auxiliary carbon source to support cell growth. Finally, the key biosynthesis genes , , and were overexpressed, resulting in an engineered strain with a heparosan titer of 622 mg/L. : This study represents the first successful engineering of EcN to utilize sucrose as the carbon source for growth, while achieving enhanced heparosan production through synergistic carbon source utilization. These findings establish a foundational strategy for employing this strain in the sucrose-based biosynthesis of other glycosaminoglycans.
乙酰肝素是K5和D型荚膜多糖的组成成分。它与肝素具有相似的聚糖结构，可通过酶促修饰产生生物活性肝素。：在本研究中，天然产生乙酰肝素的益生菌菌株Nissle 1917（EcN）经过基因工程改造，以利用蔗糖作为生长的碳源，同时实现高产的乙酰肝素生物合成。：通过表达蔗糖水解酶基因（来自）或（来自），EcN能够利用蔗糖，乙酰肝素产量分别达到131 mg/L和179 mg/L。进一步进行代谢工程以阻断糖酵解和磷酸戊糖途径，从而将蔗糖衍生的6-磷酸葡萄糖和6-磷酸果糖导向乙酰肝素生物合成，同时添加甘油作为辅助碳源以支持细胞生长。最后，关键生物合成基因、和被过表达，得到一株乙酰肝素产量为622 mg/L的工程菌株。：本研究首次成功对EcN进行工程改造，使其利用蔗糖作为生长碳源，同时通过协同利用碳源提高乙酰肝素产量。这些发现为利用该菌株进行基于蔗糖的其他糖胺聚糖生物合成奠定了基础策略。
