Fermentation method for increasing yield of L-isoleucine

The invention discloses a fermentation method for increasing the yield of L-isoleucine. The method comprises the following steps of inoculating an isoleucine production strain into a fermentation culture medium for fermentation, controlling dissolved oxygen in the fermentation process, and supplementing materials step by step to obtain the L-isoleucine. According to the method, the fermentation yield and the saccharic acid conversion rate of the isoleucine producing strain namely the L-isoleucine are increased through fermentation, the yield of the L-isoleucine is 50 g/L or above, and the saccharic acid conversion rate is 20% or above. Compared with the prior art, the yield of the L-isoleucine and the saccharic acid conversion rate are greatly increased. The content of residual sugar in fermentation liquor is controlled to be 1-2.5% by feeding glucose, substrate limitation is avoided, the glucose effect is avoided, and the production capacity of the strain is exerted to the maximum extent. Besides, dissolved