Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China.
Appl Microbiol Biotechnol. 2012 May;94(3):637-49. doi: 10.1007/s00253-011-3773-6. Epub 2012 Mar 10.
In silico metabolic network models are valuable tools for strain improvement with desired properties. In this work, based on the comparisons of each pathway flux under two different objective functions for the reconstructed metabolic network of Streptomyces roseosporus, three potential targets of zwf2 (code for glucose-6-phosphate hydrogenase), dptI (code for α-ketoglutarate methyltransferase), and dptJ (code for tryptophan oxygenase) were identified and selected for the genetic modifications. Overexpression of zwf2, dptI, and dptJ genes increased the daptomycin concentration up to 473.2, 452.5, and 489.1 mg/L, respectively. Furthermore, co-overexpression of three genes in series resulted in a 34.4% higher daptomycin concentration compared with the parental strain, which ascribed to the synergistic effect of the enzymes responsible for daptomycin biosynthesis. Finally, the engineered strain enhanced the yield of daptomycin up to 581.5 mg/L in the fed-batch culture, which was approximately 43.2% higher than that of the parental strain. These results demonstrated that the metabolic network based on in silico prediction would be accurate, reasonable, and practical for target gene identification and strain improvement.
基于对玫瑰孢链霉菌重建代谢网络在两种不同目标函数下每条途径通量的比较，本研究鉴定并选择了 zwf2（编码葡萄糖-6-磷酸氢酶）、dptI（编码α-酮戊二酸甲基转移酶）和 dptJ（编码色氨酸加氧酶）的三个潜在靶点，用于遗传修饰。zwf2、dptI 和 dptJ 基因的过表达分别将达托霉素的浓度提高到 473.2、452.5 和 489.1 mg/L。此外，三个基因的串联共过表达使达托霉素的浓度比原始菌株提高了 34.4%，这归因于负责达托霉素生物合成的酶的协同作用。最后，在补料分批培养中，工程菌株使达托霉素的产量提高到 581.5 mg/L，比原始菌株提高了约 43.2%。这些结果表明，基于计算机预测的代谢网络对于目标基因鉴定和菌株改良是准确、合理和实用的。
