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KMID : 1094720120170061196
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Biotechnology and Bioprocess Engineering
2012 Volume.17 No. 6 p.1196 ~ p.1204
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Production of β-carotene and acetate in recombinant Escherichia coli with or without mevalonate pathway at different culture temperature or pH
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Nguyen Anh Do Quynh
Kim Seon-Won
Kim Sung-Bae
Seo Yang-Gon
Chung In-Young
Kim Dae-Hwan
Kim Chang-Joon
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Abstract
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Natural β-carotene has received much attention as consumers have become more health conscious. Its production by various microorganisms including metabolically engineered Escherichia coli or Saccharomyces cerevisiae has been attempted. We successfully created a recombinant E. coli with an engineered whole mevalonate pathway in addition to β-carotene biosynthetic genes and evaluated the engineered cells from the aspects of metabolic balance between central metabolism and β-carotene production by comparison with conventional β-carotene producing recombinant E. coli (control) utilizing a native methylerythritol phosphate (MEP) pathway using bioreactor cultures generated at different temperatures or pHs. Better production of β-carotene was obtained in E. coli cultured at 37°C than at 25°C. A two-fold higher titer and 2.9-fold higher volumetric productivity were obtained in engineered cells compared with control cells. Notably, a marginal amount of acetate was produced in actively growing engineered cells, whereas more than 8 g/L of acetate was produced in control cells with reduced cell growth at 37°C. The data indicated that the artificial operon of the whole mevalonate pathway operated efficiently in redirecting acetyl-CoA into isopentenyl pyrophosphate (IPP), thereby improving production of β-carotene, whereas the native MEP pathway did not convert a sufficient amount of pyruvate into IPP due to endogenous feedback regulation. Engineered cells also produced lycopene with a reduced amount of β-carotene in weak alkaline cultures, consistent with the inhibition of lycopene cyclase.
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KEYWORD
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recombinant Escherichia coli, engineered whole mevalonate pathway, bioreactor culture, β-carotene, acetate
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