提高蛋白激发子产量的培养基及发酵条件的优化

为了进一步提高极细链格孢菌产蛋白激发子的产量，通过单因子和多因子试验与分析，筛选优化了适于极细链格孢菌产生蛋白激发子的培养基和培养条件，并检测了发酵过程中pH、还原糖、氨基氮和菌丝量变化以及与蛋白激发子产量的关系。结果表明，土豆淀粉和黄豆粉对蛋白激发子产量影响最大，其次是蛋白胨和无机盐。优化的发酵培养基主要成分（g／L）：碳源I 15、葡萄糖5、玉米淀粉5、土豆淀粉20、谷氨酸10、氮源I5、黄豆粉10、硫酸铵5。确定了优化的培养条件，调整培养基起始pH为7．0～7．5，将18h菌龄的种子培养液按10％接种量接种到装液量为75mL的500mL摇瓶中，在温度（28±1）℃、摇床转速180r／min下培养可获得理想的蛋白产量。在优化的培养基和培养条件下，发酵12～48h该菌进入对数生长期，48h进入稳定生长期，60h菌丝扣蛋白激发子产量达最高。蛋白产量与菌体生物量呈正相关，当还原糖、总糖量消耗到最低水平时，菌丝产量和蛋白激发子产量达最高。优化的培养基菌丝干重收率迭3．9g／100mL，蛋白激发子产量达到5．17g／L，比普通的土豆液体培养基提高近4倍。

Optimization of Medium and Fermentation Conditions to Increase the Production of Protein Stimulator

In order to increase the yield of protein stimulator （PS） produced by Alternaria tenuissima the production medium and fermentation conditions were screened and optimized through single and multiple factors experiments and analyses. The relation between pH, reducing sugar, amino acids, and hyphal quantity during the fermentation process and the yield of the PS was also tested. The results showed that the influences of potato starch and soybean meal were the greatest on the yield of the PS, followed by peptone and inorganic salts. The optimized basic components of the medium were as followed （g/L） ： carbon source 1 15, glucose 5, cornmeal 5, potato starch 5, glutamie acid 10, nitrogen source I 5, soybean meal 10, ammonium sulfate 5 ; the cultural conditions were optimized by adjusting the cultural initial pH value at 7.0 -7.5, and inoculated the strain seeds at 18 hours＇ instars for 10% of the inoculative quantity of 75 ml liquid medium in the 500 mL shaker flask, the temperature was controlled at （28 ± 1 ） ℃ , shaker was shaken at 180 rpm. An ideal protein production was obtained under these conditions, and the strain entered into logarithmic growing phase after 12 -48 hours＇ fermentation, and entered into stable growing phase after 48 hours, the PS and myeelia produetion reached to the peak by the 60th hour. The production of the PS positively correlated to the hyphal biomass. When the reducing sugar and total sugar amount were consumed to the lowest level, the production of the PS and the mycelia reached to the highest. The harvest rate of dried medium mycelia was 3.9 g/100 mL, and the yield of the PS was 5.17 g/L, increased by nearly 4 times as compared with the usual potato liquid medium.