The invention relates to the technical field of
biosynthesis, in particular to a method for preparing alpha-pyrrolidone. The method comprises the following steps: inoculating a
fermentation tank with a mixed strain containing
glutamate decarboxylase, and converting L-
glutamic acid into gamma-
aminobutyric acid through
fermentation; the concentration of L-
glutamic acid in the basal culture medium of the
fermentation tank is 80mM, the concentration of glucose is 10-20g / L, and C / N is equal to 15-20; when the concentration of the glucose is reduced to 5g / L, feeding is started, the feeding speed of the glucose is 0.2-0.5 g / L / h, the concentration of the L-
glutamic acid is kept at 40-110mM, the dissolved
oxygen is kept at 30-45%, and the fermentation temperature is 37-40 DEG C; fermenting for 9-12 hours, ending the fermentation, separating thalli, and retaining supernate; the method comprises the following steps: adding a culture solution into a fermentation tank, carrying out
centrifugation, carrying out sterilization treatment on a supernatant, adjusting components, continuously inoculating microorganisms with endogenous decarboxylase, carrying out fermentation, when the concentration of alpha-pyrrolidone is monitored to exceed 40g / L, dynamically exporting a
fermentation broth, carrying out
filtration separation through a hydrophobic
microfiltration membrane, returning an retentate to the fermentation tank, supplementing the culture solution, and collecting a filtrate for separation of alpha-pyrrolidone.