bacillus subtilis异丁醇合成菌株基因组尺度代谢网络模型指导的途径改造word格式论文.docx

BSUL05 produced 5.5±0.3 g/L isobutanol, which is about 70% more than that of the parental strain BSUL03. Meanwhile, isobutanol yield increased by 83% to 0.31±0.02 C-mol isobutanol/C-mol glucose (C-mol/C-mol), reaching 53% of the maximal theoretical value (0.59 C-mol/C-mol). The consistency between model prediction and experimental results demonstrates the rationality and accuracy of this model-based approach for target identification as well as strain optimization.Guided by model prediction, the present isobutanol-producing B. subtilis BSUL05 was rationally engineered for improved productivity. By disrupting glucose-6-phosphate isomerase encoding gene pgi, overexpressing the endogenous glucose-6-phosphate dehydrogenase encoding gene zwf and Escherichia coli transhydrogenase encoding gene udhA, the concentration of intracellular redox NADPH of the resulted strain BSUL08 was increased to 2.6 fold compared to the control BSUL05. Moreover, the redox equilibrium was well balanced. Under the two-stage fed-batch fermentations, isobutanol production of BSUL08 was 11% higher than that of BSUL05, reaching 6.12±0.53 g/L. Meanwhile, isobutanol yield was enhanced by 19% to 0.37 C-mol isobutanol/C-mol glucose, which is 63% of the theoretical value. These results demonstrate the significance of model-based target prediction to guide the rational metabolic engineering of the current strains. Moreover, it emphasized the importance of intracellular redox for isobutanol biosynthesis.KEY WORDS：Bacillus subtilis, Isobutanol, Synthetic biology, Metabolic network, Target prediction, Rational metabolic engineering目录第一章 文献综述11.1 异丁醇及其生产方法11.1.1 异丁醇的理化性质11.1.2 异丁醇的功能与用途11.1.3 异丁醇的生产现状21.2 合成生物学31.2.1 合成生物学的定义31.2.2 合成生物学的主要研究内容31.2.3 合成生物学的研究与发展趋势31.3 合成生物学研究异丁醇进展61.3.1 异丁醇生物合成途径及其调控机制61.3.2 宿主菌对异丁醇的压力响应及其调节机制81.3.3 异丁醇合成菌株构建研究101.3.4 异丁醇合成菌株优化策略111.4 基因组尺度代谢网络模型研究进展151.4.1 系统生物学161.4.2 细胞代谢网络模型171.4.3 细胞代谢网络模型算法181.4.4 细胞代谢网络模型应用191.5 本文主要研究内容21第二章 枯草芽孢杆菌异丁醇合成菌株构建方法242.1