With the increase in the dilution rate from 0.1 to 0.4 1/h, the biomass level in the fermentation broth remained constant, succinic acid concentration decreased from 39.6 to 18.8 g/L, byproduct acetic acid level decreased from 5.5 to 3.9 g/L, and average residual glucose concentration increased from 3.2 to 29.5 g/L, indicating that short retention time resulted in incomplete utilization of glucose.