Method for improving production of threonine by microbial fermentation

The invention belongs to the technical field of amino acid fermentation, and discloses a method for improving production of threonine by microbial fermentation. The method comprises the following steps: inoculating an escherichia coli engineering bacterium seed liquid for producing threonine by fermentation into a fermentation tank containing a fermentation culture medium according to an inoculation amount of 1-5% for carrying out fermentation, coupling the fermentation tank with a ceramic membrane, separating a primary fermentation liquid in the fermentation tank by the ceramic membrane whenfermentation is carried out for 30 hours to obtain a primary filtrate and concentrated thalli, discharging the primary filtrate, returning the concentrated thalli to the fermentation tank, adding a fermentation culture medium into the fermentation tank at the same time to enable a volume of the fermentation culture medium to be the same as a volume of the fermentation liquid before separation by the ceramic membrane, cont