Soon Ho Hong

University of Ulsan, Ulsan, Ulsan, South Korea

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Publications (58)176.55 Total impact

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    ABSTRACT: We have previously analyzed the proteome of recombinant Escherichia coli producing poly(3-hydroxybutyrate) [P(3HB)] and revealed that the expression level of several enzymes in central metabolism are proportional to the amount of P(3HB) accumulated in the cells. Based on these results, the amplification effects of triosephosphate isomerase (TpiA) and fructose-bisphosphate aldolase (FbaA) on P(3HB) synthesis were examined in recombinant E. coli W3110, XL1-Blue, and W lacI mutant strains using glucose, sucrose and xylose as carbon sources. Amplification of TpiA and FbaA significantly increased the P(3HB) contents and concentrations in the three E. coli strains. TpiA amplification in E. coli XL1-Blue lacI increased P(3HB) from 0.4 to 1.6 to g/l from glucose. Thus amplification of glycolytic pathway enzymes is a good strategy for efficient production of P(3HB) by allowing increased glycolytic pathway flux to make more acetyl-CoA available for P(3HB) biosynthesis.
    No preview · Article · Jun 2013 · Biotechnology Letters
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    ABSTRACT: Gamma-aminobutyric acid (GABA) is a precursor of one of the most promising heat-resistant biopolymers, Nylon-4, and can be produced by the decarboxylation of monosodium glutamate (MSG). In this study, a synthetic protein complex was applied to improve the GABA conversion in engineered Escherichia coli. Complexes were constructed by assembling a single protein-protein interaction domain SH3 to the glutamate decarboxylase (GadA and GadB) and attaching a cognate peptide ligand to the glutamate/GABA antiporter (GadC) at the N-terminus, C-terminus, and the 233rd amino acid residue. When GadA and GadC were co-overexpressed via the C-terminus complex, a GABA concentration of 5.65 g/l was obtained from 10 g/l MSG, which corresponds to a GABA yield of 93 %. A significant increase of the GABA productivity was also observed where the GABA productivity increased 2.5-fold in the early culture period due to the introduction of the synthetic protein complex. The GABA pathway efficiency and GABA productivity were enhanced by the introduction of the complex between Gad and glutamate/GABA antiporter.
    No preview · Article · Jun 2013 · Journal of Industrial Microbiology
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    ABSTRACT: A highly specific lead-binding peptide ThrAsnThrLeuSerAsnAsn was displayed on Escherichia coli, and lead adsorption characteristics of the recombinant bacteria were investigated. Cell surface-displayed peptide was expressed under the control of an arabinose promoter using outer membrane protein C (OmpCt) as an anchoring motif. The optimal induction period and arabinose concentration for the expression of peptide-fused OmpCt were determined to be 2 h and 0.001 g/L, respectively. Selective adsorption of Pb2+ onto recombinant cells was verified with individual or combinatory use of four metal ions, Pb2+, Ni2+, Co2+, and Cu2+; the amount of bound Pb2+ onto the biosorbents was significantly higher than the other metal ions. The adsorption isotherm of recombinant cells for Pb2+ followed the Langmuir isotherm with a maximum adsorption loading (q max) of 526 μmol/g dry cell weight.
    Full-text · Article · Jan 2013 · Applied biochemistry and biotechnology
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    ABSTRACT: Characterizing the dynamics of HydHG-a two-component transcriptional regulatory network for exogenous zinc in E. coli-is essential in understanding the biology of these regulatory and signaling pathways. Here, we used a synthetic biology strategy to modify the dynamic characteristics of the HydHG network in two ways. First, a self-activation loop for HydHG network was created under the control of zraP promoter, after which the threshold Zn(2+) concentration for the self-activated HydHG network significantly decreased from 200 to 10 μM. Second, the self-activation loop was integrated into the E. coli genome allowing the threshold Zn(2+) concentration to be elevated to 500 μM. As the threshold Zn(2+) concentration could be modified in both directions, the introduction of a self-activation loop and the entire genomic integration strategy may prove useful for the creation of a two-component bacterial biosensor with varying sensitivities.
    Full-text · Article · Nov 2012 · Bioprocess and Biosystems Engineering
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    ABSTRACT: In this study, we developed recombinant Escherichia coli strains expressing Lactococcus lactis subsp. lactis Il1403 glutamate decarboxylase (GadB) for the production of GABA from glutamate monosodium salt (MSG). Syntheses of GABA from MSG were examined by employing recombinant E. coli XL1-Blue as a whole cell biocatalyst in buffer solution. By increasing the concentration of E. coli XL1-Blue expressing GadB from the OD(600) of 2-10, the concentration and conversion yield of GABA produced from 10 g/L of MSG could be increased from 4.3 to 4.8 g/L and from 70 to 78 %, respectively. Furthermore, E. coli XL1-Blue expressing GadB highly concentrated to the OD(600) of 100 produced 76.2 g/L of GABA from 200 g/L of MSG with 62.4 % of GABA yield. Finally, nylon 4 could be synthesized by the bulk polymerization using 2-pyrrolidone that was prepared from microbially synthesized GABA by the reaction with Al(2)O(3) as catalyst in toluene with the yield of 96 %.
    No preview · Article · Sep 2012 · Bioprocess and Biosystems Engineering
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    ABSTRACT: Currently, a variety of feedstock is utilized by metabolically engineered bacteria for the production of bioenergy and biochemicals. Recent studies have shown that glycerol can be used as an alternative feedstock for glucose, considering its higher availability, lower price, and high degree of reduction. Hence, this review focuses on recent developments in the bioconversion of glycerol to bioenergy (ethanol and hydrogen) and biochemicals (1,3-propanediol, 1,2-propanediol, 3-hydroxypropionic acid, succinic acid, lactic acid, polyhydroxyalkanoates and Lphenyl alanine) using metabolically engineered Escherichia coli.
    No preview · Article · Aug 2012 · Biotechnology and Bioprocess Engineering
  • Mee-Jung Han · Sang Yup Lee · Soon Ho Hong
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    ABSTRACT: Recent genome comparisons of E. coli B and K-12 strains have indicated that the makeup of the cell envelopes in these two strains is quite different. Therefore, we analyzed and compared the envelope proteomes of E. coli BL21(DE3) and MG1655. A total of 165 protein spots, including 62 nonredundant proteins, were unambiguously identified by two-dimensional gel electrophoresis and mass spectrometry. Of these, 43 proteins were conserved between the two strains, whereas 4 and 16 strain-specific proteins were identified only in E. coli BL21(DE3) and MG1655, respectively. Additionally, 24 proteins showed more than 2-fold differences in intensities between the B and K-12 strains. The reference envelope proteome maps showed that E. coli envelope mainly contained channel proteins and lipoproteins. Interesting proteomic observations between the two strains were as follows: (i) B produced more OmpF porin with a larger pore size than K-12, indicating an increase in the membrane permeability; (ii) B produced higher amounts of lipoproteins, which facilitates the assembly of outer membrane beta-barrel proteins; and (iii) motility- (FliC) and chemotaxis-related proteins (CheA and CheW) were detected only in K-12, which showed that E. coli B is restricted with regard to migration under unfavorable conditions. These differences may influence the permeability and integrity of the cell envelope, showing that E. coli B may be more susceptible than K-12 to certain stress conditions. Thus, these findings suggest that E. coli K-12 and its derivatives will be more favorable strains in certain biotechnological applications, such as cell surface display or membrane engineering studies.
    No preview · Article · Apr 2012 · Journal of Microbiology and Biotechnology
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    ABSTRACT: The CusSR two-component system (TCS) is a copper-sensing apparatus of E. coli that is responsible for regulating the copper-related homeostatic system. The dynamic characteristics of the CusSR network were modified by the introduction of a positive feedback loop. To construct the feedback loop, the CusR, which is activated by the cusC promoter, was cloned downstream of the cusC promoter and reporter protein. The feedback loop system, once activated by environmental copper, triggers the activation of the cusC promoter, which results in the amplification of a reporter protein and CusR expression. The threshold copper concentration for the activation of the modified CusSR TCS network was lowered from 2,476.5 μg/l to 247.7 μg/l, which indicates a tenfold increase in sensitivity. The intensity of the output signal was increased twofold, and was maintained for 16 h. The strategy proposed in this study can also be applied to modify the dynamic characteristics of other TCSs.
    Full-text · Article · Feb 2012 · Journal of Industrial Microbiology
  • Min Jeong · Ik-keun Yoo · Mee Jung Han · Soon Ho Hong
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    ABSTRACT: The effect of the reducing power on the reduction of methyl-2-chlorobenzoylformate was evaluated by using carbon substrates with different reducing powers. Glucose, sorbitol, and gluconate regenerated 2, 3, and 1 NAD(P)H during its conversion to pyruvate, respectively. When sorbitol was used as the carbon substrate, complete conversion was achieved in 8 h while it took 12 h and 19 h when glucose and gluconate were used, respectively. The enantiomeric excess (ee) value was 96.7% when sorbitol was used.
    No preview · Article · Dec 2011 · Korean Journal of Chemical Engineering
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    ABSTRACT: Two new tetracationic hetero-bimetallacycles were prepared from a bis-pyridine amide ligand and metal (Pd and Pt) acceptors. We found that both self-assembled hetero-bimetallacycles bind and unwind supercoiled DNA as established by photophysical and gel electrophoresis analyses, respectively.
    Full-text · Article · Nov 2011 · Organometallics
  • Tam Dinh Le Vo · Tae Wan Kim · Soon Ho Hong
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    ABSTRACT: Gamma-aminobutyric acid (GABA) is a non-essential amino acid and a precursor of pyrrolidone, a monomer of nylon 4. GABA can be biosynthesized through the decarboxylation of L: -glutamate by glutamate decarboxylase. In this study, the effects of glutamate decarboxylase (gadA, gadB), glutamate/GABA antiporter (gadC) and GABA aminotransferase (gabT) on GABA production were investigated in Escherichia coli. Glutamate decarboxylase was overexpressed alone or with the glutamate/GABA antiporter to enhance GABA synthesis. GABA aminotransferase, which redirects GABA into the TCA cycle, was knock-out mutated. When gadB and gadC were co-overexpressed in the gabT mutant strain, a final GABA concentration of 5.46 g/l was obtained from 10 g/l of monosodium glutamate (MSG), which corresponded to a GABA yield of 89.5%.
    No preview · Article · Oct 2011 · Bioprocess and Biosystems Engineering
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    ABSTRACT: Synthetic biological systems are becoming more and more feasible for commercial and medical purposes through the genetic engineering of several components. The simple assembly of a genetic circuit was shown to stimulate the removal of copper by bacteria through the engineering of a two-component system. The CusSR two-component systems is a regulator of Escherichia coli copper homeostatic system. In this system, genetic circuits of CusSR were fused to a cell surface display system for metal adsorption; this system is suitable for the display of a copper binding peptide through outer membrane protein C (OmpC). E. coli ompC codes for an outer membrane pore protein (porin) are induced at high osmolarity and temperature, which can also be used as an anchoring motif to accept the passenger proteins. The bacteria that produce the chimeric OmpC containing the copper binding peptide adsorbed maximum concentrations of 92.2 μmol of Cu(2+)/gram dry weight of bacterial cells. This synthetic bacterial system senses the specific heavy metal and activates a cell surface display system that acts to remove the metal.
    No preview · Article · Sep 2011 · Applied biochemistry and biotechnology
  • Le Tam Dinh Vo · Soon Ho Hong
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    ABSTRACT: The type III secretion system (T3SS) is a mechanism by which bacteria export proteins from the cytoplasm, through the membranes, to the extracellular environment. T3SS is made up of more than 20 different proteins, about half of which maintain conserved sequences. This review summarizes the features of this novel apparatus and discusses the potential of utilizing T3SS to export recombinant proteins into the external environment, and the impact this system will have on protein production technology. Key wordsType III Secretion System (T3SS)–Secretion–Recombinant Protein
    No preview · Article · Jul 2011 · Korean Journal of Chemical Engineering
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    ABSTRACT: Zinc ion plays essential roles in biological chemistry. Bacteria acquire Zn(2+) from the environment, and cellular concentration levels are controlled by zinc homeostasis systems. In comparison with other homeostatic systems, the ZraSR two-component system was found to be more efficient in responding to exogenous zinc concentrations. To understand the dynamic response of the bacterium ZraSR two-component system with respect to exogenous zinc concentrations, the genetic circuit of the ZraSR system was integrated with a reporter protein. This study was helpful in the construction of an E. coli system that can display selective metal binding peptides on the surface of the cell in response to exogenous zinc. The engineered bacterial system for monitoring exogenous zinc was successfully employed to detect levels of zinc as low as 0.001 mM, which directly activates the expression of chimeric ompC(t)--zinc binding peptide gene to remove zinc by adsorbing a maximum of 163.6 μmol of zinc per gram of dry cell weight. These results indicate that the engineered bacterial strain developed in the present study can sense the specific heavy metal and activates a cell surface display system that acts to remove the metal.
    No preview · Article · Jun 2011 · Bioprocess and Biosystems Engineering

  • No preview · Article · Jan 2011 · Biotechnology and Bioprocess Engineering
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    ABSTRACT: A series of stable arenediazonium camphorsulfonate salts (2a-2j) were synthesized by simple diazotization of several aromatic amines in the presence of sodium nitrite and camphorsulfonic acid. All the new arenediazonium camphorsulfonates, which were characterized by multinuclear (H-1 and C-13) NMR, IR, DSC, and X-ray diffraction analysis (2e and 2f) provide unambiguous proof for the molecular structures of 2e and 2f. The efficient application of these salts in halogenation reactions was studied in solvent and solvent-free conditions and the DNA cleavage activity was also assessed. These arenediazonium camphorsulfonate salts are noticed as efficient DNA cleaving agents.
    No preview · Article · Jan 2011 · European Journal of Medicinal Chemistry
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    ABSTRACT: In this study, we designed and applied molecular biosensors for heavy metals, zinc and copper, for use in bioremediation strategies. Bacteria utilize two component systems to sense changes in the environment by multiple signal components including heavy metals and control gene expression in response to changes in signal molecules. zraP and cusC promoters were selected from a genetic circuit of the ZraSR and CusSR two-component system and were fused to a dual-labeling reporter protein as an interactive biological component for zinc and copper to generate a signal from the constructed biosensor. The biosensor efficiently senses zinc and copper with a calculated detection limit of 16 mu M and 26 mu M, respectively, and was shown to be a sensitive and effective heavy metal monitoring bacterial system. To extend the application of the bacterial biosensor, we assembled a bioadsorption system that can trigger bacteria to sense and adsorb 13 +/- 0.3 mg/L of zinc and 11.4 +/- 0.42 mg/L of copper per gram of dry cell weight with induction at a concentration of 100 mg/L of the respective metal ion.
    No preview · Article · Jan 2011 · PROCESS BIOCHEMISTRY
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    ABSTRACT: Methyl (R)-2-chloromandelate, a key intermediate in the synthesis of clopidogrel, was obtained by the reduction of methyl-2-chlorobenzoylformate using whole cells of Saccharomyces cerevisiae. A 100% conversion and 96.1% of enantiomeric excess (ee) value was obtained when 17 methyl-2-chlorobenzoylformate/l was reacted with 8 g S. cerevisiae/l and 83 g glucose/l at pH 7.
    No preview · Article · Oct 2010 · Biotechnology Letters
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    ABSTRACT: A single submerged membrane bioreactor (MBR) for nitrification of ammonium and a pre-denitrification MBR process for total nitrogen (TN) removal were investigated in comparison. A single nitrifying MBR was fed with synthetic ammonium wastewater of up to 900mgN/l without organics so that the MBR was maintained as a pure nitrifying system. A high nitrifying capacity around 1.8kgNH4-N/m3/day was achieved while keeping the ammonium oxidation rate above 98%. Sludge volume index (SVI) gradually decreased down to less than 50 indicating good settleability of nitrifying sludge. The increase of suction pressure was less than 5cmHg over 7-months of operation. TN removal efficiency was determined in a pre-denitrification configuration with an anoxic reactor. Synthetic wastewater of 1200mgCOD/l and 200mgN/l was fed to the system at loads of 2.4kgCOD/m3/day and 0.4kgN/m3/day, respectively. As the internal recycle ratio from aerobic to anoxic zone increased from 2 to 6, TN removal efficiency was enhanced from 70±9 to 89±3%. With the sludge concentration of around 12,000mg/l, SVI was highly fluctuated from 60 to 350 indicating the partial deterioration of sludge settleability. The suction pressure after 8 months of operation increased to above 10cmHg which is higher than that in a single nitrifying MBR. The concentration of extracellular polymeric substances (EPS), especially for carbohydrate content, was higher in the operation of a pre-denitrification MBR process than in a single nitrifying MBR. It is likely that the sludge characteristic such as settleability is related with membrane fouling but, further extensive study is needed. The performance of a pre-denitrification MBR process was also verified with real petrochemical nitrogen wastewater.
    No preview · Article · Jul 2010 · Journal of Industrial and Engineering Chemistry
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    Thuy Vu An Nguyen · Soon Ho Hong · Sang Yup Lee
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    ABSTRACT: The evolution of living organisms occurs via a combination of highly complicated processes that involve modification of various features such as appearance, metabolism and sensing systems. To understand the evolution of life, it is necessary to understand how each biological feature has been optimized in response to new environmental conditions and interrelated with other features through evolution. To accomplish this, we constructed contents-based trees for two-component system (TCS) and metabolic network to determine how the environmental communication mechanism and the intracellular metabolism have evolved, respectively. We then conducted a comparative analysis of the two trees using ARACNE to evaluate the evolutionary and functional relationship between TCS and metabolism. The results showed that such integrated analysis can give new insight into the study of bacterial evolution.
    Full-text · Article · Nov 2009 · Journal of Microbiology and Biotechnology

Publication Stats

671 Citations
176.55 Total Impact Points

Institutions

  • 2008-2016
    • University of Ulsan
      • Department of Chemical Engineering
      Ulsan, Ulsan, South Korea
  • 2012
    • Dongyang University
      South Korea
  • 1998-2004
    • Korea Advanced Institute of Science and Technology
      • • Department of Chemical and Biomolecular Engineering
      • • Metabolic and Biomolecular Engineering National Research Laboratory
      • • Bioprocess Engineering Research Center
      Seoul, Seoul, South Korea