Objective: To optimize fermentation conditions of total polysaccharides from Astragali Radix by probiotic N-14. Method: UV was adopted to determine the content of total polysaccharides with detection wavelength at 620 nm.Based on single factor tests

response surface methodology(RSM) was employed to optimize fermentation process of total polysaccharides from Astragali Radix with yield of total polysaccharides as response value and sterilization time

fermentation time

the amount of substrate as independent variables. Result: Optimum fermentation conditions were as follows:the amount of substrate 4 g

fermentation time of 24 h

sterilization time of 15 min

pH of 7

inoculation of probiotic 1%.Yield of total polysaccharides was up to 6.56%

which was lower than the predictive value of 6.69%

but 57.31% higher than yield of total polysaccharides(4.17%) by water extraction and alcohol precipitation process. Conclusion: RSM is suited to optimize fermentation process of Astragali Radix with probiotic N-14

this optimized process is stable and feasible

it provides a reference for utilization of this herb.