State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.
International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China.
J Ind Microbiol Biotechnol. 2019 Nov;46(11):1557-1568. doi: 10.1007/s10295-019-02215-0. Epub 2019 Jul 16.
L-Threonine is an important branched-chain amino acid and could be applied in feed, drugs, and food. In this study, L-threonine production in an L-threonine-producing Escherichia coli strain TWF001 was significantly increased by overexpressing the gene cluster phaCAB from Ralstonia eutropha. TWF001/pFW01-phaCAB could produce 96.4-g/L L-threonine in 3-L fermenter and 133.5-g/L L-threonine in 10-L fermenter, respectively. In addition, TWF001/pFW01-phaCAB produced 216% more acetyl-CoA, 43% more malate, and much less acetate than the vector control TWF001/pFW01, and meanwhile, TWF001/pFW01-phaCAB produced poly-3-hydroxybutyrate, while TWF001/pFW01 did not. Transcription analysis showed that the key genes in the L-threonine biosynthetic pathway were up-regulated, the genes relevant to the acetate formation were down-regulated, and the gene acs encoding the enzyme which converts acetate to acetyl-CoA was up-regulated. The results suggested that overexpression of the gene cluster phaCAB in E. coli benefits the enhancement of L-threonine production.
苏氨酸是一种重要的支链氨基酸，可应用于饲料、药物和食品。本研究通过过表达恶臭假单胞菌的phaCAB 基因簇，显著提高了苏氨酸生产大肠杆菌菌株 TWF001 的苏氨酸产量。TWF001/pFW01-phaCAB 在 3-L 发酵罐中可分别生产 96.4 g/L 的苏氨酸和 133.5 g/L 的苏氨酸。此外，与对照载体 TWF001/pFW01 相比，TWF001/pFW01-phaCAB 产生的乙酰辅酶 A 增加了 216%，苹果酸增加了 43%，乙酸减少了很多，同时，TWF001/pFW01-phaCAB 产生了聚 3-羟基丁酸，而 TWF001/pFW01 则没有。转录分析表明，苏氨酸生物合成途径中的关键基因上调，与乙酸形成相关的基因下调，编码将乙酸转化为乙酰辅酶 A 的酶的基因 acs 上调。结果表明，phaCAB 基因簇在大肠杆菌中的过表达有利于苏氨酸产量的提高。
