甲羟戊酸（MVA）是异戊烯焦磷酸（IPP）合成的关键性前体物质，而萜类化合物又由IPP经催化合成，所以MVA可以通过MVA途径间接合成各种类异戊二烯化合物，并广泛应用于食品，医药和化工行业，且市场需求旺盛。由于传统方法原料难得，能耗高，对环境污染大，且不能合成天然型的甲羟戊酸内酯（MVAL），并不适合大规模工业生产。生物法合成MVA可利用生物质降解得到的葡萄糖及工业废水中的乙酸等为原料，具有资源可持续及绿色环保的优势，成为目前的研究热点。本研究选择工业微生物常用菌株Escherichia coli作为生物催化剂，建立了以葡萄糖、乙酸等为底物，生物合成MVA的合成体系。 本研究首先以重组大肠杆菌YJM16为供试菌株，进行5 L发酵罐匀速补料的高密度发酵实验，最终细胞产量达到54.48 g•L-1，MVA产量达到40.43 g•L-1，产率为20.2 %。然后根据Logistic方程、Luedeking-Piret方程和类似Luedeking-Piret方程，拟合出重组大肠杆菌高密度发酵过程中菌体生长、MVA合成、基质消耗的动力学模型及模型参数。结果表明，MVA的合成与重组大肠杆菌的生长速率及菌体积累量均有关。菌体生长模型、底物消耗模型和产物生成模型拟合度R2分别达到了0.9319、0.9578和0.9751，可用于描述利用重组大肠杆菌高密度发酵生产MVA的过程。 过量表达acs，maeB，sfcA，yfcC，pckA和ppsA六种基因及共表达acs和maeB，sfcA，yfcC，pckA及 ppsA五种基因，构建出利用乙酸为碳源的重组菌株，进行摇瓶筛选，选出最优菌株；经摇瓶筛选发现，过量表达乙酰辅酶A合成酶ACS利于乙酸的分解利用，过量表达苹果酸酶SFCA和MAEB提供还原力，过量表达利用乙酸的糖异生关键酶PCKA和PPSA及局部调控因子YFCC，对乙酸利用及产物合成均没有明显作用，说明胞内还原力及糖异生途径并不是影响产物合成的关键因素。利用乙酸的最优菌株为表达acs的菌株FHR-2：产量和产率分别为368 mg•L-1和6.9 %，较原始菌株分别提高了31.4 %和1.47 %。 最后放大到5 L发酵罐水平进行验证，首次利用乙酸为碳源，获得MVA，并对初碳源的种类及溶氧条件进行优化，得出最优发酵条件：碳源为20 g•L-1葡萄糖，溶氧控制在20 %，通过自动流加氨水，硫酸将pH控制在7.0。培养温度37 ºC至葡萄糖耗尽，OD600nm约为19，诱导前调整为32 ºC，添加IPTG（终浓度为0.5 mM），诱导基因表达，持续发酵60 h，补料为乙酸铵以4 g•L-1•h-1的速率进行流加。实验结果：发酵结束时，OD600为20，MVA产量为8.63 g•L-1，补加乙酸铵后的产率为29.5 %（理论产率为81.67%）。

Mevalonic acid (MVA) as a key precursors of isopentenylpyrophosphate (IPP) synthesized, which can indirectly synthesis various isoprenoid compounds by MVA pathway, and widely use in food, medicine and chemical industry. Otherwise, it has an increasing market demand. However, the productions are subject to various problems by traditional methods, such as scarcity of raw materials, high cost, pollute environment and not suitable for large-scale industrial production. Biological synthesis of MVA use glucose and acetic acid as raw material, which were obtained from degradation of biomass and industrial effluents, respectively. Currently, with the advantages of resource sustainable and environment protecting, it has become the research focus. In this paper, the biosynthesis of MVA synthesis system was established by choosen industrial microbial strains Escherichia coli as a biocatalyst, glucose and acetate as the substrate, respectively. Fed-batch technique for high cell density fermentation of MVA production by recombinant Escherichia coli. YJM16 was studied. The result showed that the dry cell weight reached 54.48 g•L-1, the production of MVA was 40.43 g•L-1 and the yield was 20.2 %. The kinetics model was proposed by using the Logistic equation for cell growth, the Luedeking Piret equation for MVA production and the Luedeking -Piret -like equation for consumption of glucose as substrate. The result showed that high density fermentation kinetic of production of MVA by recombinant Escherichia coli. could be well expressed by these models. The goodness-of-fit scores R2 of models were 0.9319, 0.9578 and 0.9751, respectively. Overexpression of acs, maeB, sfcA, yfcC, pckA and ppsA gene, build the recombinant strains using acetate as carbon source, shake flask fermentation and select the optimal strain. We finded that overexpression ACS in favour of use acetic acid. Overexpression MAEB, SFCA, YFCC, PCKA and PPSA, however no enhancement of MVA production was observed. The result suggested that the level of NADPH and gluconeogenic pathway are not the main limiting factor. The optimal strain is FHR-2, the production of MVA was 368 mg•L-1 and the yield was 6.9 %. Compared with the original strain, 31.4% and 1.47% increased, respectively. 5 L fermenter fermentation: using acetic acid as carbon source, optimization fermentation conditions. During cultivation, glucose as carbon source (20 g•L-1), pH was controlled at 7.0 with NH3•H2O and H2SO4, pO2 20 %, temperature 37 ºC. When the initial glucose was depleted, reduced the temperature to 32 ºC and induction by IPTG (final concentration was 0.5 mM), ammonium acetate solution (4 g•L-1•h-1) was added. After induction for 60 h, the concentration of bacteria OD600nm reached about 20, and the concentration of MVA about 8.63 g•L-1, the yield was 29.5 % (theoretical yield 81.67%).