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Now showing items 97 - 112 of 362

  • Recent trends in metabolic engineering of microorganisms for the production of advanced biofuels

    Cheon, Seungwoo   Kim, Hye Mi   Gustavsson, Martin   Lee, Sang Yup  

    As climate change has become one of the major global risks, our heavy dependence on petroleum-derived fuels has received much public attention. To solve such problems, production of sustainable fuels has been intensively studied over the past years. Thanks to recent advances in synthetic biology and metabolic engineering technologies, bio-based platforms for advanced biofuels production have been developed using various microorganisms. The strategies for production of advanced biofuels have converged upon four major metabolic routes: the 2-ketoacid pathway, the fatty acid synthesis (FAS) pathway, the isoprenoid pathway, and the reverse beta-oxidation pathway. Additionally, the polyketide synthesis pathway has recently been attracting interest as a promising alternative biofuel production route. In this article, recent trends in advanced biofuels production are reviewed by categorizing them into three types of advanced biofuels: alcohols, biodiesel and jet fuel, and gasoline. Focus is given on the strategies of employing synthetic biology and metabolic engineering for the development of microbial strains producing advanced fuels. Finally, the prospects for future advances needed to achieve much more efficient bio-based production of advanced biofuels are discussed, focusing on designing advanced biofuel production pathways coupled with screening, modifying, and creating novel enzymes.
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  • Construction and optimization of synthetic pathways in metabolic engineering RID C-1526-2011

    Na, Dokyun   Kim, Tae Yong   Lee, Sang Yup  

    Metabolic engineering has enabled us to develop strains suitable for their use as microbial factories of chemicals and materials from renewable sources. It has recently become more powerful with the advanced in synthetic biology, which is allowing us to create novel and fine-controlled metabolic and regulatory circuits maximizing metabolic fluxes to the desired products in the strain being developed. This enables us to engineer host microorganisms to enhance their innate metabolic capabilities or to gain new capabilities in the production of target compounds. Here we review recently constructed synthetic pathways that have been successfully applied for producing non-innate chemicals and also discuss recent approaches developed to increase the efficiency of synthetic pathways for achieving higher productivities of desired bioproducts.
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  • A safe and sustainable bacterial cellulose nanofiber separator for lithium rechargeable batteries

    Gwon, Hyeokjo   Park, Kitae   Chung, Soon-Chun   Kim, Ryoung-Hee   Kang, Jin Kyu   Ji, Sang Min   Kim, Nag-Jong   Lee, Sunghaeng   Ku, Jun-Hwan   Do, Eun Cheol   Park, Sujin   Kim, Minsang   Shim, Woo Yong   Rhee, Hong Soon   Kim, Jae-Young   Kim, Jieun   Kim, Tae Yong   Yamaguchi, Yoshitaka   Iwamuro, Ryo   Saito, Shunsuke   Kim, Gahee   Jung, In-Sun   Park, Hyokeun   Lee, Chanhee   Lee, Seungyeon   Jeon, Woo Sung   Jang, Woo Dae   Kim, Hyun Uk   Lee, Sang Yup   Im, Dongmin   Doo, Seok-Gwang   Lee, Sang Yoon   Lee, Hyun Chul   Park, Jin Hwan  

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  • Metabolic engineering of Escherichia coli for the production of malic acid RID C-1526-2011

    Moon, Soo Yun   Hong, Soon Ho   Kim, Tae Yong   Lee, Sang Yup  

    Malic acid is a C-4-dicarboxylic acid and an intermediate of tricarboxylic acid (TCA) cycle. It has been widely used in the polymer, food and pharmaceutical industries. Metabolic flux analysis was performed to find a strategy for enhanced malic acid production in Escherichia coli. The simulation results suggested that the amplification of phosphoenolpyruvate (PEP) carboxylation flux allowed increased malic acid production. Since the PEP carboxylase of E. coli converts PEP to oxaloacetate without generating ATP, thus losing the high-energy phosphate bond of PEP, the PEP carboxykinase, which generates ATP during this conversion, was chosen. However, the E. coli PEP carboxykinase catalyzes the reaction that converts oxaloacetate to PEP rather than the desirable opposite reaction. Thus, we cloned the PEP carboxykinase (enconded by the pckA gene) of Mannheimia succiniciproducens, which converts PEP to oxaloacetate as a favorable reaction. The pta mutant E. coli strain WGS-10 harboring the plasmid p104ManPck containing the M. succiniciproducens pckA gene was constructed and cultured at 37 degrees C. The final malic acid concentration of 9.25 g/L could be obtained after 12 h of aerobic cultivation. (C) 2008 Elsevier B.V. All rights reserved.
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  • ENHANCED BUTANOL PRODUCING MICROORGANISMS AND METHOD FOR PREPARING BUTANOL USING THE SAME

    The present invention relates to a recombinant mutant microorganism having enhanced butanol producing capacity and a method for producing butanol using the same. In the microorganism, genes coding for enzymes responsible for the biosynthesis of lactate, ethanol and/or acetate are deleted or attenuated and genes coding for enzymes involved in butanol biosynthesis are introduced and amplified.
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  • METHOD FOR CELL SURFACE DISPLAYING OF TARGET PROTEINS USING BACILLUS ANTHRACIS EXOSPORIUM

    The present invention relates to a method for expressing a target protein on the surface of a microorganism using Bacillus anthracis exosporium protein. More particularly, to an expression vector constructed such that it comprises bclA gene encoding Bacillus anthracis exosporium protein BcIA or fragements thereof as a cell surface anchoring motif and the target protein can be expressed on the surface of a cell in a form fused with BcIA or a fragment thereof when the gene encoding the target protein is expressed in a host cell, as well as, a method for expressing a target protein on the surface of a microorganism using the vector. The expression vector according to the present invention is capable of effectively expressing a target protein or a peptide on the cell surface using BcIA, Bacillus anthracis exosporium protein as a cell surface anchoring motif, and since a target protein can be stably expressed on the cell surface in large amounts by culturing a microorganism transformed with the expression vector, thus making it possible to effectively use for the various purposes of recombinant live vaccines, whole cells absorbents, whole cell bioconversion and the like.
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  • METHOD FOR PRODUCING FATTY ACID ALKYL ESTERS USING MICROORGANISMS HAVING OIL-PRODUCING ABILITY

    The present invention relates to a method for producing fatty acid alkyl esters using microorganisms having an oil-producing ability, and more particularly to a method for producing fatty acid alkyl esters which comprises: culturing microorganisms having an oil-producing ability and accumulating oil in large amounts; degrading the produced oil to produce free fatty acids through autolysis in the microorganisms; and performing an alkyl esterification of free fatty acids. The method according to the present invention can convert oil accumulated in microorganisms such as triacyl glycerol which is an oil generally produced by microorganisms to fatty acid alkyl esters with high conversion efficiency through a metabolic engineering approach. Therefore, the present invention is useful for the industrial production of fatty acid alkyl esters which have recently been identified as a biodiesel.
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  • METHOD FOR PREDICTING A DRUG TARGET IN PATHOGENIC MICROORGANISMS USING AN ESSENTIAL METABOLITE

    The present invention relates to a method for predicting a drug target in microorganisms, and more particularly, to a method comprising: selecting subject microorganisms; building a metabolic network model of the selected microorganisms; predicting a metabolite which is essential to cell growth by applying a metabolite essentiality method; removing currency metabolite and essential metabolite, the consuming reaction formula number of which falls short of a standard; additionally selecting the remaining essential metabolite and an enzyme which consumes essential metabolite but is not involved in a host metabolism; and accordingly, screening an efficient drug target enzyme in pathogenic microorganisms or a drug target gene encoding same.
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  • L-THREONINE OVERPRODUCING MICROORGANISM AND METHOD FOR PREPARING L-THREONINE USING THE SAME

    The present invention relates to a mutant microorganism producing a high concentration of L-threonine in high yield, prepared using site-specific mutation, not random mutation, such as treatment with a mutation inducer, a method for preparing the same, and a method for preparing L-threonine using the mutant microorganism producing L-threonine. By using the mutant microorganism according to the present invention, L-threonine can be prepared at high yield, additional strain development becomes possible and their physiological phenomena can be easily understood since genetic information of L-threonine producing microorganism can be identified.
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  • Genome analysis of a hyper acetone-butanol-ethanol (ABE) producing Clostridium acetobutylicum BKM19

    Cho, Changhee   Choe, Donghui   Jang, Yu-Sin   Kim, Kyung-Jin   Kim, Won Jun   Cho, Byung-Kwan   Papoutsakis, E. Terry   Bennett, George N.   Seung, Do Young   Lee, Sang Yup  

    Previously the development of a hyper acetone-butanol-ethanol (ABE) producing Clostridium acetobutylicum BKM19 strain capable of producing 30.5% more total solvent by random mutagenesis of its parental strain PJC4BK, which is a buk mutant C. acetobutylicum ATCC 824 strain is reported. Here, BKM19 and PJC4BK strains are re-sequenced by a high-throughput sequencing technique to understand the mutations responsible for enhanced solvent production. In comparison with the C. acetobutylicum PJC4BK, 13 single nucleotide variants (SNVs), one deletion and one back mutation SNV are identified in the C. acetobutylicum BKM19 genome. Except for one SNV found in the megaplasmid, all mutations are found in the chromosome of BKM19. Among them, a mutation in the thlA gene encoding thiolase is further studied with respect to enzyme activity and butanol production. The mutant thiolase (thlA(V5A)) is showed a 32% higher activity than that of the wild-type thiolase (thlA(WT)). In batch fermentation, butanol production is increased by 26% and 23% when the thlAV5A gene is overexpressed in the wild-type C. acetobutylicum ATCC 824 and in its derivative, the thlA-knockdown TKW-A strain, respectively. Based on structural analysis, the mutation in thiolase does not have a direct effect on the regulatory determinant region (RDR). However, the mutation at the 5th residue seems to influence the stability of the RDR, and thus, increases the enzymatic activity and enhances solvent production in the BKM19 strain.
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  • The Effect of Network Density on the DNA-Sensing Performance of Single-Walled Carbon Nanotubes

    Baek, Youn-Kyoung   Yoo, Seung Min   Kim, Ju-Hyun   Jung, Dae-Hwan   Choi, Yang-Kyu   Kim, Yee Suk   Lee, Sang Yup   Jung, Hee-Tae  

    The effect of network density of single-walled carbon nanotubes (SWNTs) on the detection of DNA hybridization was investigated. The results show that, in contrast to those having higher densities, SWNTs with low network densities in the conductance range of 0.74 x 10(-7) < G(bare) < 2.00 x 10(-7) exhibit high sensitivity for detection of immobilized DNAs. The resulting SWNT devices with optimal network densities showed good selectivity in detecting cDNA hybridization. The network density control will provide opportunities to realize practical label free biosensor utilizing commercially available SWNT networks.
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  • Mannheimia succiniciproducens Phosphotransferase System for Sucrose Utilization RID C-1526-2011

    Lee, Jeong Wook   Choi, Sol   Kim, Ji Mahn   Lee, Sang Yup  

    The succinic acid producer Mannheimia succiniciproducens can efficiently utilize sucrose as a carbon source, but its metabolism has not been understood. This study revealed that M. succiniciproducens uses a sucrose phosphotransferase system (PTS), sucrose 6-phosphate hydrolase, and a fructose PTS for the transport and utilization of sucrose.
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  • Biosynthesis of poly(2-hydroxyisovalerate-co-lactate) by metabolically engineered Escherichia coli.

    Yang, Jung Eun   Kim, Je Woong   Oh, Young Hoon   Choi, So Young   Lee, Hyuk   Park, A-Reum   Shin, Jihoon   Park, Si Jae   Lee, Sang Yup  

    Polyhydroxyalkanoates (PHAs) containing 2-hydroxyacids such as lactate (LA) and 2-hydroxybutyrate (2HB) have recently been produced by metabolically engineered microorganisms. Here, we further expanded 2-hydroxyacid monomer spectrum of PHAs by engineering Escherichia coli to produce PHAs containing 2-hydroxyisovalerate (2HIV). To generate 2HIV in vivo, feedback resistant ilvBNmut genes encoding acetohydroxyacid synthase and ilvCD genes encoding ketol-acid reductoisomerase and dihydroxyacid dehydratase, respectively, and panE gene encoding d-2-hydroxyacid dehydrogenase are overexpressed. Also, pct540 gene encoding evolved propionyl-CoA transferase and phaC1437 gene encoding evolved PHA synthase are overexpressed along with ilvBNmut, ilvCD, and panE genes in E. coli strain for in vivo synthesis of 2HIV containing PHAs. E. coli strain expressing all of these genes can produce poly(13.2 mol% 2HIV-co-7.5 mol% 2HB-co-42.5 mol% 3HB-co-36.8 mol% LA) when it is cultured in a chemically defined medium containing 20 g/L of glucose and 2 g/L of sodium 3-hydroxybutyrate (3HB). To produce PHA containing only 2HIV and LA monomers, poxB, pflB, adhE and frdB genes encoding enzymes involved in competing pathways for pyruvate are deleted so that cells can generate more 2HIV and LA. When this engineered E. coli strain expressing ilvBNmut, ilvCD, panE, pct540 and phaC1437 genes is cultured in the medium containing 20 g/L of glucose and 2 mM l-isoleucine, which can inhibit l-threonine dehydratase responsible for in vivo 2HB generation, poly(20 mol% 2HIV-co-80 mol% LA) can be produced to the polymer content of 9.6% w/w. These results suggest that novel PHAs containing 2HIV can be produced by engineering branched-chain amino acid metabolism. Copyright =C2=A9 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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  • QnAs with Sang Yup Lee

    Azar, Beth  

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  • NOVEL RUMEN BACTERIA VARIANTS AND PROCESS FOR PREPARING SUCCINIC ACID EMPLOYING THE SAME

    The present invention relates to novel rumen bacterial mutants resulted from the disruption of a lactate dehydrogenase gene ( ldhA ) and a pyruvate formate-lyase gene ( pf l) (which are involved in the production of lactic acid, formic acid and acetic acid) from rumen bacteria; a novel bacterial mutant ( Mannheimia sp. LPK7) having disruptions of a lactate dehydrogenase gene ( ldhA ), a pyruvate formate-lyase gene ( plf ), a phosphotransacetylase gene ( pta ), and a acetate kinase gene ( ackA ); a novel bacterial mutant ( Mannheimia sp. LPK4) having disruptions of a lactate dehydrogenase gene ( ldhA ), a pyruvate formate-lyase gene ( pfl ) and a phosphoenolpyruvate carboxylase gene ( ppc ) involved in the immobilization of CO2 in a metabolic pathway of producing succinic acid; and a method for producing succinic acid, which is characterized by the culture of the above mutants in anaerobic conditions. The inventive bacterial mutants have the property of producing succinic acid at high concentration while producing little or no organic acids, as compared to the prior wild-type strains of producing various organic acids. Thus, the inventive bacterial mutants are useful as strains for the industrial production of succinic acid.
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  • A PROTEIN CHIP FOR ANALYZING INTERACTION BETWEEN PROTEIN AND SUBSTRATE PEPTIDE THEREOF

    The present invention relates to a protein chip of a S-L-SP form wherein a substrate peptide (SP) is immobilized on a solid substrate (S) by the mediation of a linker protein (L), as well as a method for analyzing the interaction between a reactive protein and its substrate peptide using such a protein chip. This analysis method for the interaction between a reactive protein and its substrate peptide using the protein chip comprises the steps of: adding a reactive protein to the protein chip, the reactive protein showing a specific interaction with the substrate protein immobilized on the protein chip; and detecting the interaction between the reactive protein and the substrate peptide. The present invention allows an increase in the reactivity between a peptide with low molecular weight and an enzyme with high molecular weight and between the peptide and a reactive antibody on the protein chip, so that the interaction between the peptide and the protein can be analyzed rapidly and massively.
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