| In this study we applied one-single factor and response surface method to optimize the culture medium and other conditions for strain YS1069, which would improve the yield of xylanase. First, the single factor method was used to screen eight factors including the nitrogen source, the carbon source, the inorganic salts, the inoculation volume, the liquid volume, Na2CO3, fermentation temperature and fermentation time. The optimal results corresponding to each single factor was as follows: bean cake powder 25 g/L, wheat bran 40 g/L, NaNO3 0.9 g/L, K2HPO4 3 g/L, MgSO4·7H2O 0.6 g/L, inoculums at 4%, 30 ml/250 ml (v/v) liquid volume, Na2CO3 18 g/L, cultured at 30℃ for 96 h. Secondly, these main variables were evaluated with the Plackett-Burman test. The results suggested that Na2CO3, wheat bran and MgSO4·7H2O were the most impactful factors. Finally, the optimal levels of the three factors were determined with central composite design and Design-Expert 8.05 software. The results were shown as follows: Na2CO3 21.86 g/L, wheat bran 51.41 g/L, and MgSO4·7H2O 0.59 g/L. Under the optimized conditions, the production of xylanase was increased by 5 folds. |
