Smith Geoffrey M, Lee Sarah A, Reilly Kevin C, Eiteman Mark A, Altman Elliot
Center for Molecular BioEngineering, Driftmier Engineering, University of Georgia, Athens, GA 30602, USA.
Biotechnol Lett. 2006 Oct;28(20):1695-700. doi: 10.1007/s10529-006-9142-3. Epub 2006 Aug 11.
DL-Alanine was produced from glucose in an Escherichia coli pfl pps poxB ldhA aceEF pTrc99A-alaD strain which lacked pyruvate-formate lyase, phosphoenolpyruvate (PEP) synthase, pyruvate oxidase, lactate dehydogenase, components of the pyruvate dehydogenase complex and over-produced alanine dehydrogenase (ALD). A two-phase process was developed with cell growth under aerobic conditions followed by alanine production under anaerobic conditions. Using the batch mode, cells grew to 5.3 g/l in 9 h with the accumulation of 6-10 g acetate/l, and under subsequent anaerobic conditions achieved 34 g alanine/l in 13 h with a yield of 0.86 g/g glucose. Using the fed-batch mode at micro = 0.15 h(-1), only about 1 g acetate/l formed in the 25 h required for the cells to reach 5.6 g/l, and 88 g alanine/l accumulated during the subsequent 23 h. This fed-batch process attained an alanine volumetric productivity of 4 g/lh during the production phase, and a yield that was essentially 1 g/g.
在一株缺乏丙酮酸甲酸裂解酶、磷酸烯醇式丙酮酸（PEP）合酶、丙酮酸氧化酶、乳酸脱氢酶、丙酮酸脱氢酶复合体组分且过量表达丙氨酸脱氢酶（ALD）的大肠杆菌pfl pps poxB ldhA aceEF pTrc99A-alaD菌株中，葡萄糖被转化为DL-丙氨酸。开发了一种两阶段工艺，先是在有氧条件下进行细胞生长，然后在厌氧条件下生产丙氨酸。采用分批培养模式，细胞在9小时内生长至5.3 g/l，积累了6 - 10 g/l的乙酸盐，随后在厌氧条件下，13小时内达到34 g/l的丙氨酸，葡萄糖产率为0.86 g/g。在μ = 0.15 h⁻¹的补料分批培养模式下，细胞在达到5.6 g/l所需的25小时内仅形成约1 g/l的乙酸盐，随后的23小时内积累了88 g/l的丙氨酸。该补料分批培养工艺在生产阶段的丙氨酸体积产率为4 g/l·h，产率基本为1 g/g。
