Fed-batch two-phase production of alanine by a metabolically engineered Escherichia coli.
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.
Smith
Geoffrey M
GM
Center for Molecular BioEngineering, Driftmier Engineering, University of Georgia, Athens, GA 30602, USA.
Lee
Sarah A
SA
Reilly
Kevin C
KC
Eiteman
Mark A
MA
Altman
Elliot
E
D000332:Aerobiosis; D000409:Alanine / Q000096:biosynthesis*; D050788:Alanine Dehydrogenase / Q000235:genetics / Q000378:metabolism; D000693:Anaerobiosis; D019149:Bioreactors; D004926:Escherichia coli / Q000378:metabolism*; D005285:Fermentation; D011773:Pyruvates / Q000378:metabolism
D011773:Pyruvates; D050788:Alanine Dehydrogenase; D000409:Alanine