关键词: 果葡糖浆, 肌醇, 大肠杆菌, 细胞工厂, 代谢工程

Abstract:

Objective The objective of this study is to construct an engineered Escherichia coli strain for efficientinositol production from glucose-fructose syrup by engineering fructose and glucose co-metabolism system in E. coli and establishing an inositol biosynthetic pathway. Method Using E. coli BW25113 as the starting strain, the supply of inositol precursor glucose-6-phosphate was first enhanced by blocking key nodes in the glycolysis and pentose phosphate pathway. An inositol biosynthesis module was introduced through overexpression of the Saccharomyces cerevisiae-derived inositol-3-phosphate synthase gene (Scips) and the E. coli-derived inositol monophosphatase gene (imp). Subsequently, a fructose-glucose co-utilization system was constructed by genomically integrating the S. cerevisiae-derived sedoheptulose-1,7-bisphosphatase gene (Scshb17) and the genes related to fructose transport system. Finally, efficient and stable expressions of inositol synthesis genes without antibiotics were achieved through deletion of enolase gene (eno) in the chassis strain and construction of a co-expression vector containing the inositol synthesis module and eno gene. Result When F42 glucose-fructose syrup was used as substrate for antibiotic-free fermentation, the optimized engineered strain JY18 achieved an inositol titer of 40.53 g/L, a glucose conversion rate of 0.92 g/g, and a productivity of 0.64 g/(L·h). Conclusion The developed fructose-glucose co-utilization system and the inositol synthesis module-eno coordinated expression system effectively improves the carbon source adaptability and production stability of the engineered strain, which provides innovative technical strategies and theoretical foundation for establishing a biorefinery platform using glucose-fructose syrup as feedstock.

Key words: glucose-fructose syrup, inositol, Escherichia coli, cell factory, metabolic engineering