Advanced Biotechnology: Metabolically Engineered Cells for the Bio‐Based Production of Chemicals and Fuels, Materials, and Health‐Care Products

Becker, Jörg; Wittmann, Christoph

doi:10.1002/anie.201409033

Cited by 261 publications

(165 citation statements)

References 409 publications

(301 reference statements)

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“…To become competitive with traditional chemical processes, bio‐based processes for bulk chemicals should have a minimum yield of 80% of the theoretical yield, a titer of 50 g/L and a volumetric productivity of around 3 g/L/hr (Van Dien, 2013; Werpy & Petersen, 2004). Improvements of yield and titer by genetic engineering or process optimization have been realized for a wide range of products including amino acids, organic acids, or biofuels, however, the volumetric productivity remained low in most cases (Becker & Wittmann, 2015). Reasons for low volumetric productivities are the competition between biomass and product synthesis for central metabolic precursors and, depending on the product, also growth inhibition by toxic products or intermediates.…”

Section: Introductionmentioning

confidence: 99%

Temperature‐dependent dynamic control of the TCA cycle increases volumetric productivity of itaconic acid production by Escherichia coli

Harder

Bettenbrock

Klamt

2017

Biotech & Bioengineering

103

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Based on the recently constructed Escherichia coli itaconic acid production strain ita23, we aimed to improve the productivity by applying a two‐stage process strategy with decoupled production of biomass and itaconic acid. We constructed a strain ita32 (MG1655 ΔaceA Δpta ΔpykF ΔpykA pCadCs), which, in contrast to ita23, has an active tricarboxylic acid (TCA) cycle and a fast growth rate of 0.52 hr−1 at 37°C, thus representing an ideal phenotype for the first stage, the growth phase. Subsequently we implemented a synthetic genetic control allowing the downregulation of the TCA cycle and thus the switch from growth to itaconic acid production in the second stage. The promoter of the isocitrate dehydrogenase was replaced by the Lambda promoter (p R) and its expression was controlled by the temperature‐sensitive repressor CI857 which is active at lower temperatures (30°C). With glucose as substrate, the respective strain ita36A grew with a fast growth rate at 37°C and switched to production of itaconic acid at 28°C. To study the impact of the process strategy on productivity, we performed one‐stage and two‐stage bioreactor cultivations. The two‐stage process enabled fast formation of biomass resulting in improved peak productivity of 0.86 g/L/hr (+48%) and volumetric productivity of 0.39 g/L/hr (+22%) in comparison to the one‐stage process. With our dynamic production strain, we also resolved the glutamate auxotrophy of ita23 and increased the itaconic acid titer to 47 g/L. The temperature‐dependent activation of gene expression by the Lambda promoters (p R/p L) has been frequently used to improve protein or, in a few cases, metabolite production in two‐stage processes. Here we demonstrate that the system can be as well used in the opposite direction to selectively knock‐down an essential gene (icd) in E. coli to design a two‐stage process for improved volumetric productivity. The control by temperature avoids expensive inducers and has the potential to be generally used to improve cell factory performance.

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Section: Introductionmentioning

confidence: 99%

Temperature‐dependent dynamic control of the TCA cycle increases volumetric productivity of itaconic acid production by Escherichia coli

Harder

Bettenbrock

Klamt

2017

Biotech & Bioengineering

103

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“…Diverse commercial compounds are currently produced in fermentation processes including commodity chemicals, polymers, biofuels, pharmaceuticals, nutritional supplements and so on 123…”

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confidence: 99%

Growth-coupled overproduction is feasible for almost all metabolites in five major production organisms

2017

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Computational modelling of metabolic networks has become an established procedure in the metabolic engineering of production strains. One key principle that is frequently used to guide the rational design of microbial cell factories is the stoichiometric coupling of growth and product synthesis, which makes production of the desired compound obligatory for growth. Here we show that the coupling of growth and production is feasible under appropriate conditions for almost all metabolites in genome-scale metabolic models of five major production organisms. These organisms comprise eukaryotes and prokaryotes as well as heterotrophic and photoautotrophic organisms, which shows that growth coupling as a strain design principle has a wide applicability. The feasibility of coupling is proven by calculating appropriate reaction knockouts, which enforce the coupling behaviour. The study presented here is the most comprehensive computational investigation of growth-coupled production so far and its results are of fundamental importance for rational metabolic engineering.

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“…[1] Alongside advances in “green” synthetic methodologies, the use of metabolically engineered microorganisms has emerged as a viable and elegant solution to this challenge. [2] However, maximizing titers of desired products from engineered metabolic pathways remains a central challenge in synthetic biology. This is due, in part, to the regulatory elements and metabolic enzymes that have evolved to counteract metabolite accumulation, as well as the toxicity of many of these metabolites at high concentrations.…”

mentioning

confidence: 99%

Designer Micelles Accelerate Flux Through Engineered Metabolism in E. coli and Support Biocompatible Chemistry

Wallace

Balskus

2016

Angew Chem Int Ed

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Synthetic biology has enabled the production of many value-added chemicals via microbial fermentation. However, the problem of low product titers from recombinant pathways has limited the utility of this approach. Methods to increase metabolic flux are therefore critical to the success of metabolic engineering. Here we demonstrate that vitamin E-derived designer micelles, originally developed for use in synthetic chemistry, are biocompatible and accelerate flux through a styrene production pathway in Escherichia coli. We show that these micelles associate non-covalently with the bacterial outer-membrane and that this interaction increases membrane permeability. In addition, these micelles also accommodate both heterogeneous and organic-soluble transition metal catalysts and accelerate biocompatible cyclopropanation in vivo. Overall, this work demonstrates that these surfactants hold great promise for further application in the field of synthetic biotechnology, and for expanding the types of molecules that can be readily accessed from renewable resources via the combination of microbial fermentation and biocompatible chemistry.

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Advanced Biotechnology: Metabolically Engineered Cells for the Bio‐Based Production of Chemicals and Fuels, Materials, and Health‐Care Products

Cited by 261 publications

References 409 publications

Temperature‐dependent dynamic control of the TCA cycle increases volumetric productivity of itaconic acid production by Escherichia coli

Temperature‐dependent dynamic control of the TCA cycle increases volumetric productivity of itaconic acid production by Escherichia coli

Growth-coupled overproduction is feasible for almost all metabolites in five major production organisms

Designer Micelles Accelerate Flux Through Engineered Metabolism in E. coli and Support Biocompatible Chemistry

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