发酵条件进行系统优化。发酵罐转速、通气量、初始甘油质量浓度、蛋白胨质量浓度、发酵罐的pH值设置经过优化后，琥珀酸的产量得到明显提高。发酵罐的转速600 r/min好于400 r/min，琥珀酸产量较之提高了1倍。通气量为1.0 vvm时最佳，较低时(0.5 vvm)溶氧不足、通气量较高时(2.0 vvm)溶氧过多，造成能源浪费。初始甘油质量浓度为100 g/L能保证菌体较好的生长，并且发酵较充分，琥珀酸产量达到21.0 g/L。蛋白胨的质量浓度为10.0 g/L比较适宜。发酵罐的不同pH值比较结果为，不控制pH值的自然发酵能获得最高的琥珀酸产量和产率，分别为26.3 g/L和0.27 g/g。依据以上确定的最适发酵条件进行不控制pH值的补料-分批发酵138 h，经过两次补料共消耗192.5 g/L甘油，合成46. 9 g/L琥珀酸，产率为0.24 g/g，生产率为0.34 g/(L·h)。琥珀酸的产量是优化初的5.7倍。

Using 2.5 L bench-top fermenter, fermentation was optimized for succinic acid production of recombinantYarrowia lipolyticaPGC11505. The results showed that, the output of succinic acid was enhanced substantially after the optimization of rotation speed, aeration rates, initial concentrations of glycerol and peptone, pH value of the fermenter. For detail, production of succinic acid was doubled under the speed of 600 r/min compared with 400 r/min. Aeration rate of 1.0 vvm was appropriate compared with 0.5 vvm and 2.0 vvm. Oxygen was deficient when aeration rate was low and high aeration rate would waste power and energy . PGC11505 grew well and fermentation was done totally when the initial glycerol concentration was 100 g/L, and the output of succinic acid reached 21.0 g/L. 10.0 g/L peptone was optimal for succinic production. PGC11505 performed the best when the pH value was kept natural as compared with pH value of 4.0, 5.0 and 6.0, which achieved 26.3 g/L succinic acid and a yield of 0.27 g/g. Finally, fed-batch fermentation was carried out under natural pH value for 138 hours. A total of 192.5 g/L glycerol was consumed and 46.9 g/L succinic acid was produced with a yield of 0.24 g/g and productivity of 0.34 g/(g·h). After optimization, the output of succinic acid was improved by 4.7-fold.