Corynebacterium glutamicum Tailored for Efficient Isobutanol Production

Blombach, Bastian; Riester, Tanja; Wieschalka, Stefan; Ziert, Christian; Youn, Jung-Won; Wendisch, Volker F.; Eikmanns, Bernhard J.

doi:10.1128/aem.02972-10

Cited by 280 publications

(216 citation statements)

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“…However, C. glutamicum, which is used for production of amino acids, organic acids and alcohols, does not harbor transhydrogenase genes. Recently, the introduction of transhydrogenase genes into C. glutamicum cells has been examined in an attempt to improve production of amino acids and alcohol (Bartek et al, 2011;Blombach et al, 2011;Kabus et al, 2007). However, the effect of transhydrogenases on cellular metabolism in a C. glutamicum wild-type strain has not been analyzed.…”

Section: Discussionmentioning

confidence: 99%

Enhanced acetic acid and succinic acid production under microaerobic conditions by Corynebacterium glutamicum harboring Escherichia coli transhydrogenase gene pntAB

Yamauchi¹,

Hirasawa²,

Nishii³

et al. 2014

J. Gen. Appl. Microbiol.

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Some microorganisms, such as Escherichia coli, harbor transhydrogenases that catalyze the interconversion between NADPH and NADH. However, such transhydrogenase genes have not been found in the genome of a glutamic acid-producing bacterium Corynebacterium glutamicum. In this study, the E. coli transhydrogenase genes udhA and pntAB were introduced into the C. glutamicum wild-type strain ATCC 13032, and the metabolic characteristics of the recombinant strains under aerobic and microaerobic conditions were examined. No major metabolic changes were observed following the introduction of the E. coli transhydrogenase genes under aerobic conditions. Under microaerobic conditions, significant metabolic change was not observed following the introduction of the udhA gene. However, the specific production rates of lactic acid, acetic acid, and succinic acid, and the overall production levels of acetic acid and succinic acid were increased by introducing the E. coli pntAB gene. Moreover, the NADH/NAD + ratio was increased by introduction of pntAB. Our results suggest that the E. coli PntAB transhydrogenase enhances the conversion of NADPH to NADH in C. glutamicum under microaerobic conditions, and the increased NADH/NAD + ratio results in increased succinic acid production. In addition, acetic acid production might be enhanced to supply ATP to the anaplerotic reaction catalyzed by pyruvate carboxylase.Key words: acetic acid; Corynebacterium glutamicum; pntAB; redox balance; succinic acid; transhydrogenases IntroductionMany oxidation and reduction reactions are involved in cellular metabolism, most of which require pyrimidine nucleotide cofactors, such as nicotinamide adenine dinucleotide (NAD + ) and nicotinamide adenine dinucleotide phosphate (NADP + ) and their reduced forms NADH and NADPH, to supply oxidizing and reducing equivalents. Generally, NADH is produced via catabolism, and is oxidized in the respiratory chain under aerobic conditions or by fermentation under anaerobic conditions. Anabolic reactions to produce cell biomass components, such as fatty acid and amino acid biosynthesis, require NADPH as a reducing equivalent. Therefore, maintaining the intracellular balance of NAD(P) + and NAD(P)H is very important for most intracellular metabolic reactions to occur.Some organisms contain the enzymes catalyzing the following interconversion of NADH and NADPH, called transhydrogenase:NADPH + NAD + NADP + + NADH. To date, two types of transhydrogenases have been identified; the cytoplasmic-soluble and membrane-bound types. Membrane-bound transhydrogenases have been found in the inner mitochondrial membrane of eukaryotic cells and in the cytoplasmic membrane of many bacteria, and simultaneously catalyze proton translocation across a membrane. Full PaperEnhanced acetic acid and succinic acid production under microaerobic conditions by Corynebacterium glutamicum harboring Escherichia coli transhydrogenase gene pntAB (Received April 3, 2014; Accepted April 8, 2014) Yuto Yamauchi, None of the authors of this manuscript ha...

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Section: Discussionmentioning

confidence: 99%

Enhanced acetic acid and succinic acid production under microaerobic conditions by Corynebacterium glutamicum harboring Escherichia coli transhydrogenase gene pntAB

Yamauchi¹,

Hirasawa²,

Nishii³

et al. 2014

J. Gen. Appl. Microbiol.

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“…Studies of Corynebacterium glutamicum engineered for isobutanol formation indicated a cycle consisting of pyruvate and/or phosphoenolpyruvate carboxylase, malate dehydrogenase, and malic enzyme provided conversion of NADH + H + to NADPH + H + , aided synthesis [55]. Engineering C. glutamicum for valine production by removing pyruvate dehydrogenase activity enhanced flux through the pentose phosphate pathway providing additional NADPH while adding E. coli PntAB decreased the pentose phosphate pathway flux [56].…”

Section: Cofactor Considerations In Metabolic Engineeringmentioning

confidence: 99%

Cofactor engineering for advancing chemical biotechnology

Wang

San

Bennett

2013

Current Opinion in Biotechnology

135

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Cofactors provide redox carriers for biosynthetic reactions, catabolic reactions and act as important agents in transfer of energy for the cell. Recent advances in manipulating cofactors include culture conditions or additive alterations, genetic modification of host pathways for increased availability of desired cofactor, changes in enzyme cofactor specificity, and introduction of novel redox partners to form effective circuits for biochemical processes and biocatalysts. Genetic strategies to employ ferredoxin, NADH and NADPH most effectively in natural or novel pathways have improved yield and efficiency of large-scale processes for fuels and chemicals and have been demonstrated with a variety of microbial organisms.

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“…6) Alternatively, and like many aerobic and facultative anaerobic bacteria, C. glutamicum is also capable of producing organic acids under anaerobic conditions. Using wild-type or recombinant strains, organic acids such as succinate and lactate have been reported to be produced in significant amounts, [7][8][9][10] but also alcohols such as ethanol 11) and isobutanol, 12) under oxygen-depleted conditions. In C. glutamicum, a metabolic switch that takes place during the transition from aerobic to anaerobic conditions has been documented.…”

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confidence: 99%