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Highly efficient L-lactate production using engineered Escherichia coli with dissimilar temperature optima for L-lactate formation and cell growth

dc.contributor.authorNiu, Dandanen_ZA
dc.contributor.authorTian, Kangmingen_ZA
dc.contributor.authorPrior, Bernard A.en_ZA
dc.contributor.authorWang, Minen_ZA
dc.contributor.authorWang, Zhengxiangen_ZA
dc.contributor.authorLu, Fupingen_ZA
dc.contributor.authorSingh, Surenen_ZA
dc.date.accessioned2014-07-28T09:15:22Z
dc.date.available2014-07-28T09:15:22Z
dc.date.issued2014
dc.identifier.citationNiu, D. et al. 2014. Highly efficient L-lactate production using engineered Escherichia coli with dissimilar temperature optima for L-lactate formation and cell growth. Microbial Cell Factories, 13(1):78, doi:10.1186/1475-2859-13-78.en_ZA
dc.identifier.issn1475-2859 (online)
dc.identifier.otherdoi:10.1186/1475-2859-13-78
dc.identifier.urihttp://hdl.handle.net/10019.1/95513
dc.descriptionCITATION: Niu, D. et al. 2014. Highly efficient L-lactate production using engineered Escherichia coli with dissimilar temperature optima for L-lactate formation and cell growth. Microbial Cell Factories, 13(1):78, doi:10.1186/1475-2859-13-78.en_ZA
dc.descriptionThe original publication is available at http://www.microbialcellfactories.com/content/13/1/78en_ZA
dc.description.abstractL-Lactic acid, one of the most important chiral molecules and organic acids, is produced via pyruvate from carbohydrates in diverse microorganisms catalyzed by an NAD+-dependent L-lactate dehydrogenase. Naturally, Escherichia coli does not produce L-lactate in noticeable amounts, but can catabolize it via a dehydrogenation reaction mediated by an FMN-dependent L-lactate dehydrogenase. In aims to make the E. coli strain to produce L-lactate, three L-lactate dehydrogenase genes from different bacteria were cloned and expressed. The L-lactate producing strains, 090B1 (B0013-070, ΔldhA::diflldD::Pldh-ldhLca), 090B2 (B0013-070, ΔldhA::diflldD::Pldh-ldhStrb) and 090B3 (B0013-070, ΔldhA::diflldD::Pldh-ldhBcoa) were developed from a previously developed D-lactate over-producing strain, E. coli strain B0013-070 (ack-ptappspflBdldpoxBadhEfrdA) by: (1) deleting ldhA to block D-lactate formation, (2) deleting lldD to block the conversion of L-lactate to pyruvate, and (3) expressing an L-lactate dehydrogenase (L-LDH) to convert pyruvate to L-lactate under the control of the ldhA promoter. Fermentation tests were carried out in a shaking flask and in a 25-l bioreactor. Strains 090B1, 090B2 or 090B3 were shown to metabolize glucose to L-lactate instead of D-lactate. However, L-lactate yield and cell growth rates were significantly different among the metabolically engineered strains which can be attributed to a variation between temperature optimum for cell growth and temperature optimum for enzymatic activity of individual L-LDH. In a temperature-shifting fermentation process (cells grown at 37°C and L-lactate formed at 42°C), E. coli 090B3 was able to produce 142.2 g/l of L-lactate with no more than 1.2 g/l of by-products (mainly acetate, pyruvate and succinate) accumulated. In conclusion, the production of lactate by E. coli is limited by the competition relationship between cell growth and lactate synthesis. Enzymatic properties, especially the thermodynamics of an L-LDH can be effectively used as a factor to regulate a metabolic pathway and its metabolic flux for efficient L-lactate production. Highlights The enzymatic thermodynamics was used as a tool for metabolic regulation. ► minimizing the activity of L-lactate dehydrogenase in growth phase improved biomass accumulation. ► maximizing the activity of L-lactate dehydrogenase improved lactate productivity in production phase.en_ZA
dc.format.extent11 pages : illustrationsen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherBioMed Centralen_ZA
dc.subjectEscherichia coli -- Biotechnologyen_ZA
dc.subjectL-lactate dehydrogenaseen_ZA
dc.subjectEnzymatic thermodynamicsen_ZA
dc.subjectEngineered Escherichia colien_ZA
dc.titleHighly efficient L-lactate production using engineered Escherichia coli with dissimilar temperature optima for L-lactate formation and cell growthen_ZA
dc.typeArticleen_ZA
dc.date.updated2014-06-30T15:03:37Z
dc.description.versionPublishers' Versionen_ZA
dc.rights.holderDandan Niu et al.; licensee BioMed Central Ltd.en_ZA


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