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Now showing items 65 - 80 of 362

  • Engineering Clostridial Aldehyde/Alcohol Dehydrogenase for Selective Butanol Production

    Cho, Changhee   Hong, Seungpyo   Moon, Hyeon Gi   Jang, Yu-Sin   Kim, Dongsup   Lee, Sang Yup   Lovley, Derek R.  

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  • Systems Biology and Biotechnology of Escherichia coli ||

    Lee, Sang Yup  

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  • METHOD FOR PREPARING SUCCINIC ACID USING GLYCEROL AS CARBON SOURCE

    The present invention relates to a method for preparing succinic acid using glycerol as a carbon source, and more particularly, a method for preparing succinic acid with high purity and high yield, which comprises inoculating Mannheimia sp., which is a facultative anaerobic microorganism, into a culture medium containing glycerol as a carbon source and anaerobically culturing, then recovering succinic acid. According to the present invention, a significant amount of succinic acid can be produced compared with the methods using carbon sources such as glucose or sucrose, and formation of total by-products is inhibited or prevented upon microbial fermentation, thus making it possible to reduce costs required for separating and purifying succinic acid from final culture broth.
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  • METHOD FOR PURIFYING SUCCINIC ACID BY CRYSTALLIZATION OF CULTURE BROTH

    The present invention relates to a method for separating and purifying succinic acid with high purity and high yield by crystallization of culture broth and, more particularly, a method for recovering succinic acid with high purity and high yield, which comprises concentrating culture broth from which succinic acid-producing microorganism is removed and then adding an acid solution at low temperature, thus directly crystallizing without other pretreatment processes. According to the present invention, succinic acid is separated and purified using culture broth, from which succinic acid producing microorganism is removed, without other pretreatment processes, and thus a cost-saving effect due to process simplification, and an effect of environmental pollution prevention due to the prevention of sludge generation during succinic acid recovery process, can be achieved. In addition, succinic acid was recovered with high purity and high yield, thus making it possible to achieve a technical effect unprecedented in the prior art in terms of cost efficiency.
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  • METHOD FOR PREPARING SUCCINIC ACID USING SUCROSE AS A CARBON SOURCE

    The present invention relates to a method for preparing succinic acid, which comprises culturing a succinic acid-producing microorganism in a medium containing sucrose as a carbon source, and more particularly, a method for preparing succinic acid, which comprises culturing a succinic acid-producing microorganism under batch or fed-batch culture conditions in a medium containing sucrose as a carbon source at a high concentration. According to the present invention, when inexpensive sucrose, whose price corresponds to 28.9% of glucose price, is used as a carbon source, microorganisms have improved resistance against organic acids including succinic acid compared to the case using other carbon sources such as glucose to significantly increase succinic acid productivity as well as final succinic acid concentration, thus making it possible to reduce costs required for separating and purifying succinic acid.
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  • Metabolic engineering of Escherichia coli for the production of 3-aminopropionic acid.

    Song, Chan Woo   Lee, Joungmin   Ko, Yoo-Sung   Lee, Sang Yup  

    A novel metabolic pathway was designed for the production of 3-aminopropionic acid (3-AP), an important platform chemical for manufacturing acrylamide and acrylonitrile. Using a fumaric acid producing Escherichia coli strain as a host, the Corynebacterium glutamicum panD gene (encoding L-aspartate-alpha-decarboxylase) was overexpressed and the native promoter of the aspA gene was replaced with the strong trc promoter, which allowed aspartic acid production through the aspartase-catalyzed reaction. Additional overexpression of aspA and ppc genes, and supplementation of ammonium sulfate in the medium allowed production of 3.49 g/L 3-AP. The 3-AP titer was further increased to 3.94 g/L by optimizing the expression level of PPC using synthetic promoters and RBS sequences. Finally, native promoter of the acs gene was replaced with strong trc promoter to reduce acetic acid accumulation. Fed-batch culture of the final strain allowed production of 32.3 g/L 3-AP in 39 h. Copyright =C2=A9 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.
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  • Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation.

    Joo, Seongjoon   Cho, In Jin   Seo, Hogyun   Son, Hyeoncheol Francis   Sagong, Hye-Young   Shin, Tae Joo   Choi, So Young   Lee, Sang Yup   Kim, Kyung-Jin  

    Plastics, including poly(ethylene terephthalate) (PET), possess many desirable characteristics and thus are widely used in daily life. However, non-biodegradability, once thought to be an advantage offered by plastics, is causing major environmental problem. Recently, a PET-degrading bacterium, Ideonella sakaiensis, was identified and suggested for possible use in degradation and/or recycling of PET. However, the molecular mechanism of PET degradation is not known. Here we report the crystal structure of I. sakaiensis PETase (IsPETase) at 1.5A resolution. IsPETase has a Ser-His-Asp catalytic triad at its active site and contains an optimal substrate binding site to accommodate four monohydroxyethyl terephthalate (MHET) moieties of PET. Based on structural and site-directed mutagenesis experiments, the detailed process of PET degradation into MHET, terephthalic acid, and ethylene glycol is suggested. Moreover, other PETase candidates potentially having high PET-degrading activities are suggested based on phylogenetic tree analysis of 69 PETase-like proteins.=20
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  • Systems metabolic engineering, industrial biotechnology and microbial cell factories

    Lee, Sang Yup   Mattanovich, Diethard   Villaverde, Antonio  

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  • Biorefineries for the production of top building block chemicals and their derivatives.

    Choi, Sol   Song, Chan Woo   Shin, Jae Ho   Lee, Sang Yup  

    Due to the growing concerns on the climate change and sustainability on petrochemical resources, DOE selected and announced the bio-based top 12 building blocks and discussed the needs for developing biorefinery technologies to replace the current petroleum based industry in 2004. Over the last 10 years after its announcement, many studies have been performed for the development of efficient technologies for the bio-based production of these chemicals and derivatives. Now, ten chemicals among these top 12 chemicals, excluding the l-aspartic acid and 3-hydroxybutyrolactone, have already been commercialized or are close to commercialization. In this paper, we review the current status of biorefinery development for the production of these platform chemicals and their derivatives. In addition, current technological advances on industrial strain development for the production of platform chemicals using micro-organisms will be covered in detail with case studies on succinic acid and 3-hydroxypropionic acid as examples. Copyright =C2=A9 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.
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  • METHOD FOR PRODUCING POLYHYDROXYALKANOATE CONTAINING 2-HYDROXYBUTYRATE AS THE MONOMER

    The present invention relates to a method for producing a polyhydroxyalkanoate containing 2-hydroxybutyrate as the monomer, and more specifically, to a method for producing a polyhydroxyalkanoate containing 2-hydroxybutyrate from recombinant strains using metabolic engineering. The present invention provides a recombinant microorganism capable of producing a polyhydroxyalkanoate containing 2-hydroxybutyrate, a novel biodegradable polymer, as the monomer, and a method for producing a polyhydroxyalkanoate containing 2-hydroxybutyrate as the monomer by culturing recombinant microorganisms.
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  • Metabolic engineering of Clostridium acetobutylicum for the production of butyl butyrate.

    Noh, Hyeon Ji   Woo, Ji Eun   Lee, Sang Yup   Jang, Yu-Sin  

    Butyl butyrate is widely used as a fragrance additive for foods and beverages. The first step in the currently used process is the production of precursors, including butanol and butyrate, from petroleum using chemical catalysts, followed by the conversion of precursors to butyl butyrate by immobilized lipase. In this work, we engineered Clostridium acetobutylicum for the selective, one-step production of butyl butyrate from glucose. C. acetobutylicum ATCC 824, possessing a strong carbon flux that yields butanol and butyryl-CoA, was selected as a host and was engineered by introducing alcohol acyltransferases (AATs) from Fragaria x ananassa (strawberry) or Malus sp. (apple). Batch culture of the engineered C. acetobutylicum strain CaSAAT expressing the strawberry SAAT gene produced 50.07mg/L of butyl butyrate with a selectivity of 84.8% of total esters produced. Also, the engineered C. acetobutylicum strain CaAAAT expressing the apple AAAT gene produced 40.60mg/L of butyl butyrate with a selectivity of 87.4%. This study demonstrated the feasibility of the one-step fermentation of butyl butyrate from glucose in the engineered C. acetobutylicum, as a proof of concept.=20
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  • METHOD FOR SCREENING ESSENTIAL METABOLITES IN GROWTH OF MICROORGANISMS

    The present invention disclosed is a method for screening metabolites essential for the growth of microorganism using metabolic flux analysis. More specifically, the present invention relates to the method for screening metabolites essential for the growth of microorganism, by selecting a target microorganism, constructing a metabolic network model of the selected microorganism, inactivating the consumption reaction of each of metabolites in the constructed metabolic network model, analyzing the metabolic flux of the metabolites to select metabolites essential for the growth of the microorganism, and confirming the selected metabolites using the utilization of each of the metabolites, defined as flux sum (Φ ). According to the present invention, metabolites essential for the growth of microorganism, and genes involved in the essential metabolites, can be screened in a convenient manner, and drug-target genes against pathogenic microorganisms can be predicted by deleting genes associated with the metabolites screened according to the method.
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  • Efficient gene knockdown in Clostridium acetobutylicum by synthetic small regulatory RNAs

    Cho, Changhee   Lee, Sang Yup  

    Clostridium is considered a promising microbial host for the production of valuable industrial chemicals. However, Clostridium is notorious for the difficulty of genetic manipulations, and consequently metabolic engineering. Thus, much effort has been exerted to develop novel tools for genetic and metabolic engineering of Clostridium strains. Here, we report the development of a synthetic small regulatory RNA (sRNA)-based system for controlled gene expression in Clostridium acetobutylicum, consisting of a target recognition site, MicC sRNA scaffold, and an RNA chaperone Hfq. To examine the functional operation of sRNA system in C. acetobutylicum, expression control was first examined with the Evoglow fluorescent protein as a model protein. Initially, a C. acetobutylicum protein annotated as Hfq was combined with the synthetic sRNA based on the Escherichia coli MicC scaffold to knockdown Evoglow expression. However, C. acetobutylicum Hfq did not bind to E. coli MicC, while MicC scaffold-based synthetic sRNA itself was able to knockdown the expression of Evoglow. When E. coli hfq gene was introduced, the knockdown efficiency assessed by measuring fluorescence intensity, could be much enhanced. Then, this E. coli MicC scaffold-Hfq system was used to knock down adhE1 gene expression in C. acetobutylicum. Knocking down the adhE1 gene expression using the synthetic sRNA led to a 40% decrease in butanol production (2.5g/L), compared to that (4.5g/L) produced by the wild-type strain harboring an empty vector. The sRNA system was further extended to knock down the pta gene expression in the buk mutant C. acetobutylicum strain PJC4BK for enhanced butanol production. The PJC4BK (pPta-Hfq(Eco)) strain, which has the pta gene expression knocked down, was able to produce 16.9g/L of butanol, which is higher than that (14.9g/L) produced by the PJC4BK strain, mainly due to reduced acetic acid production. Fed-batch culture of PJC4BK (pPta-Hfq(Eco)) strain coupled with in situ gas stripping produced 105.5g of total solvents (70.7g butanol, 20.5g acetone, and 14.3g ethanol), demonstrating that the sRNA-based engineered C. acetobutylicum strain can be cultured without instability. The synthetic sRNA system reported in this study will be useful for more efficient development of engineered C. acetobutylicum strains capable of producing valuable chemicals and fuels. Biotechnol. Bioeng. 2017;114: 374-383. (c) 2016 Wiley Periodicals, Inc.
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  • RECOMBINANT MICROORGANISM HAVING AN ABILITY OF USING SUCROSE AS A CARBON SOURCE

    The present invention relates to a recombinant microorganism capable of metabolizing sucrose, and more particularly to a recombinant microorganism capable of metabolizing sucrose in which a gene encoding sucrose phosphotransferase and/or a gene encoding sucrose-6-phosphate hydrolase is introduced or to a recombinant microorganism capable of metabolizing sucrose in which a gene encoding β-fructofuranosidase is introduced. According to the present invention, a recombinant microorganism capable of using inexpensive sucrose as a carbon source instead of expensive glucose is provided. In addition, in a process of culturing microorganisms which have been incapable of using sucrose as a carbon source, sucrose can substitute for other carbon sources including glucose.
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  • METHOD FOR PREPARING BUTANOL THROUGH BUTYRYL-COA AS AN INTERMEDIATE USING YEAST

    Disclosed herein are a method for producing butanol in yeast having the ability to biosynthesize butanol using butyryl-CoA as an intermediate, the method comprises producing butyryl-CoA in yeast having a CoAT (acetyl-CoA:butyryl- CoA CoA-transferase)-encoding gene introduced thereinto, through various pathways, and then converting the produced butyryl-CoA to butanol.
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  • Synthetic biology and metabolic engineering of actinomycetes for natural product discovery

    Palazzotto, Emilia   Tong, Yaojun   Lee, Sang Yup   Weber, Tilmann  

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