Fed-batch two-phase production of alanine by a metabolically engineered Escherichia coli

• Published in: Biotechnology letters 2006-10, Vol.28 (20), p.1695-1700
• Main Authors: Smith, Geoffrey M, Lee, Sarah A, Reilly, Kevin C, Eiteman, Mark A, Altman, Elliot
• Format: Article
• Language: English
• Subjects: Acetate; Aerobic conditions; Aerobiosis; alanine; Alanine - biosynthesis; alanine dehydrogenase; Alanine Dehydrogenase - genetics; Alanine Dehydrogenase - metabolism; Anaerobic conditions; Anaerobiosis; Biological and medical sciences; Bioreactors; Biotechnology; E coli; Enzymes; Escherichia coli; Escherichia coli - metabolism; Fed-batch process; Fermentation; Fundamental and applied biological sciences. Psychology; Overflow metabolism; Pyruvates - metabolism
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/s10529-006-9142-3

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 μ = 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.