Metabolic engineering of Bacillus subtilis for de novo synthesis of 6′-sialyllactose
Qi Chen , Xianhao Xu , Zhengyan Sun , Yu Wang , Yanfeng Liu , Jianghua Li , Guocheng Du , Xueqin Lv , Long Liu
Systems Microbiology and Biomanufacturing ›› : 1 -14.
Metabolic engineering of Bacillus subtilis for de novo synthesis of 6′-sialyllactose
6′-sialyllactose (6′-SL) is an important component of human milk oligosaccharides (HMOs) and has numerous infant health benefits. The construction of efficient and food-safe microbial cell factories to produce 6′-SL has attracted increasing attention. In this study, a Bacillus subtilis strain was metabolically engineered for 6′-SL production. First, a de novo synthesis pathway for 6′-SL was constructed by heterologous expression of neuC, neuB, neuA, and pst6, enabling 6′-SL synthesis at a titer of 135.17 mg/L. Subsequently, bioinformatics-guided enzyme modification and promoter substitution strategies were used to fine-tune the pathway strength. Moreover, inhibition of competing pathways and copy number optimization of synthetic modules were used to increase the precursor concentration, raising 6′-SL titer to 621.8 mg/L. Furthermore, a strategy to overcome carbon catabolite repression (CCR) was developed for B. subtilis to improve lactose utilization and increase 6′-SL titers, reaching 3.55 g/L in shake flasks and 15.0 g/L in 3-L fermenters. This study established a foundation for efficient 6′-SL production.
the National Key Research and Development Program of China ,(2022YFC3401303)
the National Natural Science Foundation of China,(32070085)
the National Natural Science Foundation of China ,(32200050)
the Natural Science Foundation of Jiangsu Province ,(BK20221079)
the Fundamental Research Funds for the Central Universities,(JUSRP52019A)
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