期刊
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
卷 70, 期 27, 页码 8351-8364出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jafc.2c03053
关键词
Escherichia coli; colanic acid; metabolic engineering; acetate; acetyl-phosphate; undecaprenyl phosphate; O-antigen; enterobacterial common antigen
资金
- National Key Research and Development Program of China [2018YFA0900300]
- Key Technology Project of Inner Mongolia Autonomous Region in China [2019GG302]
This study aimed to improve the production of colanic acid in E. coli by modifying metabolic pathways. Strategies of deleting genes related to acetate production, O-antigen synthesis, and overexpressing genes involved in lipid carrier synthesis were implemented. The engineered strain achieved significantly higher colanic acid production compared to the control strain.
ABSTRACT: Colanic acid is a major exopolysaccharide existing in most Enterobacteriaceae when exposed to an extreme environment. Colanic acid possesses excellent physical properties and biological activities, which makes it a candidate in the food and healthcare market. Previous strategies for colanic acid overproduction in E. coli mainly focus on removing the negative regulator on colanic acid biosynthesis or overexpressing the rcsA gene to up-regulate the cps operon. In this study, modifications in metabolic pathways were implemented in E. coli mutant strains with shortened lipopolysaccharides to improve colanic acid production. First, ackA was deleted to remove the byproduct acetate and the effect of accumulated acetyl-phosphate on colanic acid production was investigated. Second, 11 genes responsible for O-antigen synthesis were deleted to reduce its competition for glucose-1-phosphate and UDP-galactose with colanic acid production. Third, uppS was overexpressed to supply lipid carriers for synthesizing a colanic acid repeat unit. Colanic acid production in the final engineered strain WZM008/pTrcS reached 11.68 g/L in a 2.0 L bioreactor, 3.54 times the colanic acid production by the WQM001 strain. The results provide insights for further engineering E. coli to maximize CA production.
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