摘要构建了Acetobacter xylinum NUST4.2合成细菌纤维素（Bacterial Cellulose，简称BC）的代谢网络。在拟稳态假设的基础上，通过碳代谢平衡和Matlab软件进行线性规划，得到摇瓶和发酵罐发酵各时间段的代谢通量分布。对实验结果分析表明发酵前段时间葡萄糖大量流入磷酸戊糖途径（PPP）、三羧酸循环（TCA）、副产物、BC合成以及菌体合成；发酵后期细胞以葡萄糖酸为主要能源物质。整个发酵过程存在大量的无效循环。部分代谢流流向副产物，所以可通过代谢工程手段对菌株进行遗传改造和培养条件优化，阻断或削弱流向无益方向的代谢流，从而提高目的产物BC的产量。64758

毕业论文关键词  Acetobacter xylinum NUST4.2；细菌纤维素；代谢网络；代谢通量分析

毕业设计说明书（论文）外文摘要

Title  Construction of the Metabolic Network and Flux Analysis of

        Acetobacter xylinum NUST4.2 

Abstract

The metabolic network of Acetobacter xylinum NUST4.2 for bacterial cellulose(abbr. BC)biosynthesis was constructed. Based on the quasi-steady state，the metabolic flux distribution of the shake flask and fermentor in each time period was calculated by carbon metabolic balance and Matlab software for linear programming. The results of this study showed that a large influx of glucose enters PPP,TCA and the synthesis of byproducts, BC and cells in fermentation earlier stage; And in the later stage, gluconic acid is the main carbon source. During the fermentation, a lot of futile cycles were existed and some metabolic fluxes entered the byproducts. Therefore, by means of metabolic engineering strains for genetic transformation and optimization of culture conditions, blocking or weakening the unhelpful flow direction of metabolic flux，the byproducts formation was reduced and the yield of BC could be improved. 

Keywords  Acetobacter xylinum NUST4.2; bacterial cellulose; metabolic network; metabolic flux analysis

目   次

1  绪论 1

1.1  课题的研究背景和意义 1

1.2  细菌纤维素的结构与特性 2

1.2.1  细菌纤维素的结构 2

1.2.2  细菌纤维素的特性 2

1.3  细菌纤维素的生物合成 3

1.3.1  木醋杆菌的代谢网络 3

1.3.2  细菌纤维素的合成酶系统 4

1.3.3  细菌纤维素合成调控 4

1.4  细菌纤维素代谢通量分析 5

1.5  课题研究内容 6

2  材料与方法 6

2.1  实验仪器 6

2.2  实验试剂 7

2.3  菌种 7

2.4  培养基配方 7

2.5  分析方法 8

2.5.1  葡萄糖的测定 8

2.5.2   pH测定 8

2.5.3  葡萄糖酸的测定[20] 8

2.5.4  乙酸的测定[21] 9

2.5.5  BC产量测定 9

2.5.6  菌体质量浓度的测定