不同葡萄糖转运途径相关基因的过表达对菌株葡萄糖代谢及产物合成的影响

Overexpression of genes related to glucose transport system in Corynebacterium glutamicum ZL-8 and their effects on glucose metabolism and L-lysine synthesis

磷酸烯醇式丙酮酸-葡萄糖磷酸转移酶系统(phosphoenolpyruvate-dependent glucose phosphotransferase system,PTS^(Glc))和不依赖于PTS^(Glc)系统葡萄糖转运系统在葡萄糖转运和磷酸化过程中起重要作用。该文通过在葡萄糖代谢缓慢的L-赖氨酸产生菌Corynebacterium glutamicum(C.glutamicum)ZL-8中过表达肌醇透性酶基因(iol T1)、葡萄糖激酶基因(ppgk)和EIIGlc基因(pts G),研究葡萄糖转运途径相关基因对葡萄糖代谢速率、L-赖氨酸及副产物合成的影响。与出发菌株C.glutamicum ZL-8相比,重组菌C.glutamicum ZL-8/p ECXK-99E-ppgkiol T1(葡萄糖激酶酶活力提高了768%)和C.glutamicum ZL-8/p DXW-8-pts G(PTS^(Glc)系统酶活力提高了62.7%)葡萄糖消耗速率分别提高了16.7%和27.3%,L-赖氨酸产量分别提高了24.7%和16.4%。此外,有机酸和氨基酸分析结果表明,过表达不同葡萄糖转运途径基因对有机酸(丙酮酸、乳酸和乙酸)和副产物氨基酸(丙氨酸、缬氨酸、天冬氨酸)具有不同的影响。

Corynebacterium glutamicum （C. glutamicum） ZL-8 is an L-lysine producing strain of mutation breed- ing with low rate of glucose uptake and phosphorylation. Phosphoenolpyruvate-dependent glucosephospho-transferase system （ PTSGlc ） and PTSG＇C-independent play an important role in the process of glucose uptake and phosphorylation. In this paper, the roles of EIIGlc , IolT1, glucokinase in glucose metabolic rate, L-lysine yield and by-products accu- mulation were investigated by overexpressing EII^Gle （ptsG） , IolT1 （JolT1） , glucokinase （ppgk）coding genes in L-ly- sine producing strain Corynebacterium glutamicum ZL-8. Compared with the original strain, the L-lysine yield and glucose metabolic rate of the recombinant strain C. glutamicum ZL-8/pDXW-8-ptsG （increased by 27.3% and 16. 4% , respectively） and C. glutamicum ZL-8/pECXK-99E-ppgk-iolT1 （increased by 16.7% and 24.7% , respective- ly） were increased by overexpressing the genes in glucose transport system. In addition, the activity of PTSGlc system in C. glutamicum ZL-8/pDXW-8-ptsG was increased by 62.7% , whereas the activity of glucokinase in C. glutami- cum ZL-8/pECXK-99E-ppgk-iolT1 was increased by 768%. Meanwhile, results indicated that the accumulation of or- ganic acids （pyruvic acid, lactic acid and acetic acid） and amino acids （valine, alanine, aspartic acid） changed more obviously during overexpression of the different genes involved in glucose transport system.