FEED LIQUID FOR PRODUCTION OF POLYSIALIC ACID, AND PREPARATION METHOD FOR POLYSIALIC ACID

The present invention relates to the technical field of microbial fermentation, and in particular to a feed liquid for the production of polysialic acid, and a preparation method for the polysialic acid. By means of investigating the kinetic behavior of Escherichia coli fermentation for producing the polysialic acid under NaCl stress, a production method for increasing the yield of the polysialic acid by means of flow-feed NaCl is provided, wherein the feeding quantity of the flow-feed NaCl is 20 g/L fermentation medium to 40 g/L fermentation medium, and when said feeding quantity is reached 4 h to 6 h before the end of the fermentation, the increase in the yield of the polysialic acid is particularly significant. Furthermore, provided are a NaCl-containing feed liquid and use thereof in the production of the polysialic acid by Escherichia coli fed-batch fermentation. The production method is beneficial for increasing the yield of the polysialic acid, and facilitates the ethanol precipitation and separation o