Tan Mei-Juan, Chen Xi, Wang Yu-Kuan, Liu Guang-Lei, Chi Zhen-Ming
College of Marine Life Sciences, Ocean University of China, Yushan Road, No. 5, Qingdao, China.
Bioprocess Biosyst Eng. 2016 Aug;39(8):1289-96. doi: 10.1007/s00449-016-1607-8. Epub 2016 Apr 21.
In this study, after the expression of a pyruvate carboxylase gene (PYC) cloned from Meyerozyma guilliermondii in a marine-derived yeast Yarrowia lipolytica SWJ-1b, a transformant PG86 obtained had much higher PYC activity than Y. lipolytica SWJ-1b. At the same time, the PYC gene expression and citric acid (CA) production by the transformant PG86 were also greatly enhanced. When glucose concentration in the medium was 60.0 g L(-1), CA concentration formed by the transformant PG86 was 34.02 g L(-1), leading to a CA yield of 0.57 g g(-1) of glucose. During a 10-L fed-batch fermentation, the final concentration of CA was 101.0 ± 1.3 g L(-1), the yield was 0.89 g g(-1) of glucose, the productivity was 0.42 g L(-1) h(-1) and only 5.93 g L(-1) reducing sugar was left in the fermented medium within 240 h of the fed-batch fermentation. HPLC analysis showed that most of the fermentation products were CA.
在本研究中，将从季也蒙毕赤酵母克隆的丙酮酸羧化酶基因（PYC）在海洋来源的解脂耶氏酵母SWJ-1b中表达后，获得的转化子PG86的PYC活性比解脂耶氏酵母SWJ-1b高得多。同时，转化子PG86的PYC基因表达和柠檬酸（CA）产量也大大提高。当培养基中葡萄糖浓度为60.0 g L⁻¹时，转化子PG86形成的CA浓度为34.02 g L⁻¹，葡萄糖的CA产量为0.57 g g⁻¹。在10 L补料分批发酵过程中，CA的最终浓度为101.0±1.3 g L⁻¹，产量为0.89 g g⁻¹葡萄糖，生产率为0.42 g L⁻¹ h⁻¹，在补料分批发酵的240 h内发酵培养基中仅残留5.93 g L⁻¹还原糖。高效液相色谱分析表明，大部分发酵产物为CA。
