l-Valine biosynthesis during batch and fed-batch cultivations of Corynebacterium glutamicum: Relationship between changes in bacterial growth rate and intracellular metabolism

Ruklisha, Maija; Paegle, Longina; Denina, I.

doi:10.1016/j.procbio.2006.11.008

Cited by 24 publications

(21 citation statements)

References 33 publications

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“…Because of the deletion of the threonine dehydratase (ilvA gene product), the amount of available L-isoleucine is determining the end of growth phase [20] and the final biomass concentration. Compared to literature, the calculated L-isoleucine content of biomass (48 lmol/g CDW) is lower.…”

Section: Resultsmentioning

confidence: 99%

Influence of l-isoleucine and pantothenate auxotrophy for l-valine formation in Corynebacterium glutamicum revisited by metabolome analyses

Bartek

Makus

Klein

et al. 2008

Bioprocess Biosyst Eng

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The effect of different amounts of supplemented L-isoleucine and pantothenate has been analysed with the auxotrophic strain Corynebacterium glutamicum DeltailvA DeltapanB, showing that the final biomass concentration of this preliminary L-valine production strain can be controlled by the amount of added L-isoleucine. One gramme cell dry weight is formed from 48 micromol L-isoleucine. Different amounts of available pantothenate affect the intracellular pyruvate concentration. By limiting pantothenate supplementation from 0.8 to 0.1 microM, a 35-fold increase of cytoplasmic pyruvate up to 14.2 mM can be observed, resulting in the increased formation of L-valine, L-alanine and organic acids in the presence of low pantothenate concentrations. These findings can be used to redirect the carbon flux from glycolysis via pyruvate to the TCA cycle towards the desired product L-valine.

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Section: Resultsmentioning

confidence: 99%

Influence of l-isoleucine and pantothenate auxotrophy for l-valine formation in Corynebacterium glutamicum revisited by metabolome analyses

Bartek

Makus

Klein

et al. 2008

Bioprocess Biosyst Eng

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“…50,51 However, Ruklisha et al 8 also showed decreasing intracellular NADPH concentrations during L-valine formation. Our own analysis of the C. glutamicum wild type revealed an intracellular NADPH concentration of 0.03 lM during growth phase.…”

Section: L-valine Formation and Intracellular Nadph Concentrations Afmentioning

confidence: 99%

“…44 The importance of NADPH for the formation of amino acids such as L-lysine is known and was the subject for several studies. 13,45 A possible improvement of L-valine yield after optimized cofactor supply has been suggested by Ruklisha et al 8 using the C. glutamicum DilvA DpanBC strains.…”

Section: Different Elementary Modes As Archetypes For the Constructiomentioning

confidence: 99%

“…[5][6][7][8] The published production strains are mainly based on the deletion of the threonine dehydratase gene (ilvA) to abolish the competing pathway toward L-isoleucine and the deletion of a-ketoisovalerate hydroxymethyltransferase gene (panB) to limit the flux from pyruvate via the pyruvate dehydrogenase complex (PDHC) into the tricarboxylic acid cycle (TCA cycle). Recently, Park et al 9 also described an L-valine-producing Escherichia coli strain with a similar genotype.…”

Section: Introductionmentioning

confidence: 99%

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Importance of NADPH supply for improved L‐valine formation in Corynebacterium glutamicum

Bartek

Blombach

Zönnchen

et al. 2009

Biotechnology Progress

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Cofactor recycling is known to be crucial for amino acid synthesis. Hence, cofactor supply was now analyzed for L-valine to identify new targets for an improvement of production. The central carbon metabolism was analyzed by stoichiometric modeling to estimate the influence of cofactors and to quantify the theoretical yield of L-valine on glucose. Three different optimal routes for L-valine biosynthesis were identified by elementary mode (EM) analysis. The modes differed mainly in the manner of NADPH regeneration, substantiating that the cofactor supply may be crucial for efficient L-valine production. Although the isocitrate dehydrogenase as an NADPH source within the tricarboxylic acid cycle only enables an L-valine yield of Y(Val/Glc) = 0.5 mol L-valine/mol glucose (mol Val/mol Glc), the pentose phosphate pathway seems to be the most promising NADPH source. Based on the theoretical calculation of EMs, the gene encoding phosphoglucoisomerase (PGI) was deleted to achieve this EM with a theoretical yield Y(Val/Glc) = 0.86 mol Val/mol Glc during the production phase. The intracellular NADPH concentration was significantly increased in the PGI-deficient mutant. L-Valine yield increased from 0.49 +/- 0.13 to 0.67 +/- 0.03 mol Val/mol Glc, and, concomitantly, the formation of by-products such as pyruvate was reduced.

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“…A transition in the cellular growth rate to below maximum during batch-and fed-batch cultivations has been determined to be a precondition for increasing AHAS activity and L-valine synthesis by C. glutamicum ilvA panBC (pJC1ilvBNCD), which is auxotrophic for L-isoleucine and D-pantothenate [41]. L-Valine oversynthesis due to the high AHAS activity in various recombinant C. glutamicum strains auxotrophic for L-isoleucine has also been observed under conditions of L-isoleucine limitation [17,25,36].…”

Section: Introductionmentioning

confidence: 99%

Factors enhancing l-valine production by the growth-limited l-isoleucine auxotrophic strain Corynebacterium glutamicum ΔilvA ΔpanB ilvNM13 (pECKAilvBNC)

Denina

Paegle

Prouza

et al. 2010

J Ind Microbiol Biotechnol

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Cell growth limitation is known to be an important condition that enhances L: -valine synthesis in Corynebacterium glutamicum recombinant strains with L: -isoleucine auxotrophy. To identify whether it is the limited availability of L: -isoleucine itself or the L: -isoleucine limitation-induced rel-dependent ppGpp-mediated stringent response that is essential for the enhancement of L: -valine synthesis in growth-limited C. glutamicum cells, we deleted the rel gene, thereby constructing a relaxed (rel (-) ) C. glutamicum DeltailvA DeltapanB Deltarel ilvNM13 (pECKAilvBNC) strain. Variations in enzyme activity and L: -valine synthesis in rel (+) and rel (-) strains under conditions of L: -isoleucine excess and limitation were investigated. A sharp increase in acetohydroxy acid synthase (AHAS) activity, a slight increase in acetohydroxyacid isomeroreductase (AHAIR) activity, and a dramatic increase in L: -valine synthesis were observed in both rel (+) and rel (-) cells exposed to L: -isoleucine limitation. Although the positive effect of induction of the stringent response on AHAS and AHAIR upregulation in cells was not confirmed, we found the stringent response to be beneficial for maintaining increased AHAS, dihydroxyacid dehydratase, and transaminase B activity and L: -valine synthesis in cells during the stationary growth phase.

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l-Valine biosynthesis during batch and fed-batch cultivations of Corynebacterium glutamicum: Relationship between changes in bacterial growth rate and intracellular metabolism

Cited by 24 publications

References 33 publications

Influence of l-isoleucine and pantothenate auxotrophy for l-valine formation in Corynebacterium glutamicum revisited by metabolome analyses

Influence of l-isoleucine and pantothenate auxotrophy for l-valine formation in Corynebacterium glutamicum revisited by metabolome analyses

Importance of NADPH supply for improved L‐valine formation in Corynebacterium glutamicum

Factors enhancing l-valine production by the growth-limited l-isoleucine auxotrophic strain Corynebacterium glutamicum ΔilvA ΔpanB ilvNM13 (pECKAilvBNC)

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