The present invention provides a recombinant microorganism for producing citicoline and a method for producing citicoline by using the recombinant microorganism, wherein genes for degradation and utilization of citicoline, choline, and phosphocholine are knocked out, In addition, a pyrimidine nucleoside synthesis pathway is genetically engineered to remove feedback inhibition to the synthesis pathway. A yield of more than 20 g/L of citicoline can be obtained with recombinant strains in a 5-liter fermenter by means of a biological fermentation method, achieving industrial mass production with low citicoline production costs and less pollution; therefore, the method is a simple, environmentally friendly and has a relatively high promotion and application value.

The present invention in various aspects and embodiments provides engineered bacterial strains having a modified genome that provides advantages in maintenance and biosynthetic processes when cultured at large scale. The present invention further provides methods for large-scale fermentation using the bacterial strains. In various embodiments, the strain engineering yields a reduction in cellular responses to micro-environmental stimuli imposed in large scale bioreactors.

The present invention provides a recombinant microorganism for producing citicoline and a method for producing citicoline by using the recombinant microorganism, wherein genes for degradation and utilization of citicoline, choline, and phosphocholine are knocked out, In addition, a pyrimidine nucleoside synthesis pathway is genetically engineered to remove feedback inhibition to the synthesis pathway. A yield of more than 20 g/L of citicoline can be obtained with recombinant strains in a 5-liter fermenter by means of a biological fermentation method, achieving industrial mass production with low citicoline production costs and less pollution; therefore, the method is a simple, environmentally friendly and has a relatively high promotion and application value.

Disclosed herein are metabolically engineered cells capable of producing carotenoids from acid whey.