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The main byproducts and metabolic flux profiling of γ-PGA-producing strain B. subtilis ZJU-7 under different pH values

Paper ID Volume ID Publish Year Pages File Format Full-Text
23562 43452 2013 8 PDF Available
Title
The main byproducts and metabolic flux profiling of γ-PGA-producing strain B. subtilis ZJU-7 under different pH values
Abstract

Poly-γ-glutamic acid (γ-PGA) is an extracellular anionic polymer with many potential applications. Although microbial fermentation is the common approach to produce γ-PGA, the broth at the latter stage usually becomes very viscous and severely influences the metabolites producing pattern of target microbe. In this study, acetoin and 2,3-butanediol were confirmed to be the main byproducts of γ-PGA-producing strain B. subtilis ZJU-7 (B. subtilis CGMCC1250), and their effects on the cell growth and γ-PGA biosynthesis were further investigated in shake flasks. The outcome indicated that both acetoin and 2,3-butanediol showed clear impairment on γ-PGA production of B. subtilis ZJU-7. Moreover, the extracellular metabolites profiles of fermentation under three different pH values were acquired and the metabolic flux redistribution of pathways related to γ-PGA biosynthesis was calculated based on the collected data. As a result, the metabolic flux favored to distribute toward glycolytic pathway at pH 6.5, in which the ingestion rate of extracellular glutamic acid was higher and the subsequent γ-PGA biosynthesis was enhanced. The present work provided us a deep insight into the metabolic flux control of γ-PGA biosynthesis, which will stimulate some novel metabolic engineering strategies to improve the productivity of γ-PGA in future.

► Acetoin and 2,3-butanediol were confirmed as the main byproducts in B. subtilis ZJU-7. ► Extracellular metabolite profiles of PGA fermentation were acquired at three pH values. ► Pathways of byproducts were included in metabolic network modeling of PGA biosynthesis. ► Metabolic flux redistribution of PGA and byproducts formation was calculated.

Keywords
G6P, glucose-6-phosphate; F6P, fructose-6-phosphate; R5P, ribulose-5-phosphate; T3P, triose-3-phosphate pool; Xyl5P, xylulose-5-phosphate; Rib5p, ribose-5-phosphate; E4P, erythrose-4-phosphate; S7P, seduheptulose-7-phosphate; PG3, 3-phosphoglycerate; C1,
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The main byproducts and metabolic flux profiling of γ-PGA-producing strain B. subtilis ZJU-7 under different pH values
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 164, Issue 1, 10 March 2013, Pages 67–74
Authors
, , , , , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us