Abstract:In order to increase the mannitol productivity of (Lactobacillus fermentation) LS33, the fermentation conditions of LS33 were researched. Response surface methodology was used to design experiment on the basis of single factor experiment results, a quadratic regression model of fructose concentration, initial pH value and temperature was established by Design Expert 7.0. The optimal fermentation conditions were determined as follows: fructose concentration 75 g/L, initial pH value 6.9, temperature 42 ℃, inoculums size 10% and shaker speed 120 r/min, undert these conditions, the mannitol productivity was 53.66%, increased by 18.93% than before (45.12%).