Genetically engineered bacterium for producing d-pantothenic acid, construction method therefor and use thereof

Abstract

A genetically engineered bacterium that produces D-pantothenic acid and a construction method therefor, and the use of the engineered bacterium in the preparation of D-pantothenic acid by means of microbial fermentation. In the present invention, mainly by means of: (1) increasing the copy number of key genes in the pantoic acid synthesis pathway in Escherichia coli organisms to further make carbon flux flow to the synthesis of D-pantothenic acid, and (2) in order to keep enhancing the flow of carbon flux to the synthesis of D-pantothenic acid, negatively regulating a transcription factor by means of weakening the nitrogen limitation and activating glycolytic front-end genes to pull the carbon flow so as to save phosphoenolpyruvic acid and reduce the central carbon flow that enters TCA, an engineered strain for producing D-pantothenic acid with no plasmid or antibiotic addition is obtained. Finally, the titer of D-pantothenic acid in the shake flask is increased by 87.2% compared to that of the starting strain, and reaches 5.43 g / L. After fermentation in a 5-L fermentation tank for 84 hours, the yield of D-pantothenic acid can reach 94.2 g / L.

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