• Korean Journal of Microbiology
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• v.51 no.3
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• pp.271-279
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• 2015

Lactoferrin (LF) is a multifunctional, iron-binding glycoprotein found in physiological secretions of mammals. LF shows antibacterial, antiviral and antifungal activities. In the present study, a gene encoding the N-terminal lobe of human lactoferrin (hLF) was isolated, cloned and expressed in methylotrophic yeast, Pichia pastoris. The recombinant hLF-N (rhLF-N) protein was secreted into the culture medium at the level of $458{\mu}g/ml$ in 3 L fermentor. The size of purified hLF-N was estimated as 35 kDa when analyzed by SDS-PAGE and western blotting. The rhLF-N was further confirmed by immunodiffusion using the anti-hLF polyclonal antibody. The expression profile analysis by qRT-PCR showed that the relative mRNA expression of rhLF-N was maximal after 2-3 days of methanol induction and reduced gradually at 4 days. The purified rhLF-N showed broad antibacterial activities against the pathogens such as Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, Burkholderia cepacia, and Salmonella typhimurium. However, rhLF-N showed relatively lower activity when compared to peptides derived from LF. In spite of this weak activity, the rhLF-N expressed in P. pastoris might be more advantageous for the industrial application, because rhLF-N is secreted into the culture medium and the production can also be increased by optimization of culture conditions.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.153-159
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• 2009

Recombinant Escherichia coli BLR(DE3) harboring the hemA gene from Rhodobacter capsulatus under the control of a constitutive promoter, which we constructed previously, was used for the extracellular production of 5-aminolevulinic acid (ALA). The effects of several factors on ALA production were investigated in flask culture. ALA production by the recombinant E. coli was more efficient at $30^{\circ}C$ than $37^{\circ}C$. The glycine concentration had an important effect on cell growth. Glycine and succinic acid concentration of 5-10 and 10-20 g/L, respectively, resulted in high ALA production. In addition, the partial replacement of succinic acid by sodium glutamate increased the ALA production. The ALA production was inhibited by the presence of glucose in the medium. Using the optimal conditions, an ALA concentration of 8.2 g/L was achieved in jar fermentation without an added inducer or ALA dehydratase inhibitor; this is the highest reported concentration.

• KSBB Journal
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• v.4 no.1
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• pp.21-30
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• 1989

Lauryl alcohol was used as extracting solvent of ethanol, and its toxicity on the free cells or immobilized cells was tested. To increase ethanol productivity, extractive fermentation method combined with ethanol fermentation and ethanol recovery was applied to the immobilized batch and continuous fermenter. As the concentration of LaOH was increased, the lag phase became longer, but specific growth rate did not change greatly. And a cell entrapment technique could protect the yeast cells against both substrate inhibition and solvent toxicity. When the glucose concentration was 400 g/l and the LaOH/fermentation medium ratio was 4, total ethanol productivity increased with the enhancement of LaOH volume, and maximum productivity was 2.75 g/l.hr in the immobilized batch fermentation.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.40-44
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• 2003

Soil-borne infectious disease including Pythium aphanidermatum and Rhizoctonia solani causes severe damage to plants, such as cucumber. This soil-borne infectious disease was not controlled effectively by chemical pesticide. Since these diseases spread through the soil, chemical agents are usually ineffective. Instead, biological control, including antagonistic microbe can be used as a preferred control method. An efficient method was developed to select an antagonistic strain to be used as a biological control agent strain. In this new method, surface tension reduction potential of an isolate was included in the ‘decision factor’ in addition to the other factors, such as growth rate, and pathogen inhibition rate. Considering these 3 decision factors by a statistical method, an isolate from soil was selected and was identified as Bacillus sp. GB16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth was observed when Bacillus sp. GB16 was used. Therefore this strain was considered as plant growth promoting rhizobacteria (PGPR). The action of surface tension reducing component was deduced as the enhancement of wetting, spreading, and residing of antagonistic strain in the rhizosphere. This result showed that new selection method was significantly effective in selecting the best antagonistic strain for biological control of soil-borne infectious plant pathogen. The antifungal substances against P. aphanidermatum and R. solani were partially purified from the culture filtrates of Bacillus sp. GB16. In this study, lipopeptide possessing antifungal activity was isolated from Bacillus sp. GB16 cultures by various purification procedures and was identified as a surfactin-like lipopeptide based on the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high performance liquid chromatography mass spectroscopy (HPLC-MS), and quadrupole time-of-flight (Q-TOF) ESI-MS/MS data. The lipopeptide, named GB16-BS, completely inhibited the growth of Pythium aphanidermatum, Rhizoctonia solani, Penicillium sp., and Botrytis cineria at concentrations of 10 and 50 mg/L, respectively. A novel method to prevent the foaming and to provide oxygen was developed. During the production of surface active agent, such as lipopeptide (surfactin), large amount of foam was produced by aeration. This resulted in the carryover of cells to the outside of the fermentor, which leads to the significant loss of cells. Instead of using cell-toxic antifoaming agents, low amount of hydrogen peroxide was added. Catalase produced by cells converted hydrogen peroxide into oxygen and water. Also addition of corn oil as an oxygen vector as well as antifoaming agent was attempted. In addition, Ca-stearate, a metal soap, was added to enhance the antifoam activity of com oil. These methods could prevent the foaming significantly and maintained high dissolved oxygen in spite of lower aeration and agitation. Using these methods, high cell density, could be achieved with increased lipopeptide productivity. In conclusion to produce an effective biological control agent for soil-borne infectious disease, following strategies were attempted i) effective screening of antagonist by including surface tension as an important decision factor ii) identification of antifungal compound produced from the isolated strain iii) novel oxygenation by $H_2O_2-catalase$ with vegetable oil for antifungal lipopeptide production.

• Journal of Life Science
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• v.27 no.8
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• pp.930-936
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• 2017

The flocculating properties of bioflocculant Biopol32 produced by Pseudomonas sp. GP32 were investigated for application in industrial wastewater treatment. The major flocculating substance of bioflocculant Biopol32 was identified as polysaccharide. Many anionic flocculants need a counter ion to induce higher flocculating activity. The flocculating activity of bioflocculant Biopol32 was markedly increased by the addition of cationic ions ($Ca^{2+}$, $Al^{3+}$). The flocculating activity of bioflocculant Biopol32 was the most effective when 7.0 mM $CaCl_2{\cdot}2H_2O$ as coflocculant was added. The flocculating activity on the effect of pH and the temperature of the bioflocculant Biopol32 was compared with anionic commercial flocculant (polyacrylamide) and bioflocculant (zooglan from Zoogloea ramigera). In kaolin suspension, the highest flocculating activity was obtained at the bioflocculant Biopol32 concentration of 1.5 mg/l. A high flocculating activity was observed in the pH range of 5.0 to 8.0. The flocculating activity of bioflocculant Biopol32 was sustained up to $60^{\circ}C$, but decreased rapidly at over $70^{\circ}C$. In the batch culture, the charge density of bioflocculant Biopol32 was compared with flocculating activity. The larger the anionic charge density and apparent viscosity of bioflocculant Biopol32, the higher the flocculating activity. Therefore, we confirmed that the flocculating activity and apparent viscosity of bioflocculant Biopol32 was closely related to the charge density of bioflocculant Biopol32.

• The Korean Journal of Food And Nutrition
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• v.18 no.1
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• pp.39-47
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• 2005

Using the bacteria isolated from Chungkookjang, Bacillus sublilis MG410 which is excellent in fibrinolytic enzyme activity was isolated. In increase the high production of fibrinolytic enzyme from Bacillus sublilis MG410, the effect of various carbon sources, nitrogen sources, inorganic sources, the initial pH of medium were investigated. The most effective carbon and nitrogen sources were founded cellobiose 0.5%(w/v) and soybean meal 2%(w/v) respectively. None of inorganic sources examined had any detectable stimulating effect on fibrinolytic enzyme production except Na₂HPO₄·12H₂O. The initial optimum pH for fibrinolytic enzyme production ranged from 5∼6 and agitation speed was effect at 150rpm. In jar fermentor experiments under optimal culture conditions, the activity of fibrinolytic enzyme reached about 5.050 unit after 48hours.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2004.06a
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• pp.60-61
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• 2004

Metabolic engineering is now a well established discipline, used extensively to determine and execute rational strategies of strain development to improve the performance of micro-organisms employed in industrial fermentations. The basic principle of this approach is that performance of the microbial catalyst should be adequately characterised metabolically so as to clearlyidentify the metabolic network constraints, thereby identifying the most probable targets for genetic engineering and the extent to which improvements can be realistically achieved. In order to harness correctly this potential, it is clear that the physiological analysis of each strain studied needs to be undertaken under conditions as close as possible to the physico-chemical environment in which the strain evolves within the full-scale process. Furthermore, this analysis needs to be undertaken throughoutthe entire fermentation so as to take into account the changing environment in an essentially dynamic situation in which metabolic stress is accentuated by the microbial activity itself, leading to increasingly important stress response at a metabolic level. All too often these industrial fermentation constraints are overlooked, leading to identification of targets whose validity within the industrial context is at best limited. Thus the conceptual error is linked to experimental design rather than inadequate methodology. New tools are becoming available which open up new possibilities in metabolic engineering and the characterisation of complex metabolic networks. Traditionally metabolic analysis was targeted towards pre-identified genes and their corresponding enzymatic activities within pre-selected metabolic pathways. Those pathways not included at the onset were intrinsically removed from the network giving a fundamentally localised vision of pathway functionality. New tools from genome research extend this reductive approach so as to include the global characteristics of a given biological model which can now be seen as an integrated functional unit rather than a specific sub-group of biochemical reactions, thereby facilitating the resolution of complexnetworks whose exact composition cannot be estimated at the onset. This global overview of whole cell physiology enables new targets to be identified which would classically not have been suspected previously. Of course, as with all powerful analytical tools, post-genomic technology must be used carefully so as to avoid expensive errors. This is not always the case and the data obtained need to be examined carefully to avoid embarking on the study of artefacts due to poor understanding of cell biology. These basic developments and the underlying concepts will be illustrated with examples from the author's laboratory concerning the industrial production of commodity chemicals using a number of industrially important bacteria. The different levels of possibleinvestigation and the extent to which the data can be extrapolated will be highlighted together with the extent to which realistic yield targets can be attained. Genetic engineering strategies and the performance of the resulting strains will be examined within the context of the prevailing experimental conditions encountered in the industrial fermentor. Examples used will include the production of amino acids, vitamins and polysaccharides. In each case metabolic constraints can be identified and the extent to which performance can be enhanced predicted

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.137-142
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• 1998

Helicobacter pylori is a Gram-negative bacterium which causes chronic gastritis and is associated with gastric ulcer, duodenal ulcer and gastric carcinoma. In the process of screening of antibacterial activities against H. pylori from soil microorganisms, fungus No. 60686 was isolated. After fermentation of No.60686, the antibacterial compound was isolated, purified and followed by extraction of mycelium with organic solvents, acetone and ethyl acetate, through silica gel chromatography, LH-20 gel chromatography and HPLC. As a result of the structural analyses of the compound by IR, $^1$H- and $^{13}$C-NMR, FAB/Mass spectrophotometer, the compound having the antimicrobial activity was identified as chaetoglobosin A ($C_{32}H_{36}N_2O_5$), a cytochalasan derivative. The antimicrobial activity of chaetoglobosin A was tested against Gram-positive and negative bacteria by paper disk method. Among the test strains of 9 Gram-positive bacteria and 18 Gram-negative bacteria containing 4 H. pylori strains, the growth of 4 H. pylori strains and 3 S. aureus strains (SG 511, 285 and 503) was only inhibited by chaetoglobosin A. Also it was shown that its growth inhibition against H. pylori strains was stronger than that against S. aureus strains at the treatment of the same concentration. Therefore it was concluded that chaetoglobosin A has a specific growth inhibition against H. pylori of the tested bacteria.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.249-254
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• 2011

Mycophenolic acid blocking the synthesis of xanthosine monophosphate is a nonnucleoside inhibitor of inosine monophosphate dehydrogenase. Therefore mycopholoic acid is a drug currently used as immunosuppressive agent in transplantation of heart, kidney and liver. Mycophenolic acid has been industrially produced through fermentation process by fungus Penicillium brevi-compactum. In this study, the profile of mycophenolic acid fermentation was observed in 5L-jar fermentor to investigate the utilization of carbon and nitrogen sources and the production of mycophenolic acid. It was investigated that what kind of carbon sources was better to cell growth and mycophenolic acid production. Fructose was the best carbon source for mycophenolic acid fermentation, but it is the most expensive one. Thereafter molasses containing sucrose as the supply source of fructose was confirmed to be the best carbon source for the industrial production. Use of molasses increased the fermentation yield of mycophenolic acid more than two times higher than glucose. It was confirmed that urea was the best inorganic nitrogen source, which did not give rise to sudden drop of culture pH. Addition of urea increased the fermentation yield of mycophenolic acid about 3.6 times higher than addition of ammonium nitrate as control. Casein, peptone and casamino acid originated from milk protein increased the fermentation yield of mycophenolic acid about 3.4 times higher than control. Peptone and casamino acid, which are casein hydrolysates, increased cell growth considerably as well.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.1
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• pp.53-66
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• 1998

This study was carried out to investigate the typical composition of food waste from municipal solid wastes (MSW) and unit food waste generation rates from different sources in the model cities and to study the food waste management system from unit household to composting facilities. The annual average food waste composition of MSW was determined as 49% in Taejon and 52% in Chungnam Province, respectively. No big difference in food waste composition was found among the different sources. Since the paper waste generally occupied the half of food waste, over 75% of MSW was found to be compostable or biodegradable. Per capita food waste generation rate, 200~250g/capita day was determined by the direct measurement from 32 households, while 380g/capita day for Chungnam Province and 400 g/capita day for Taejon were estimated by the load count analysis In the sanitary landfills. This difference means people contribute generating food waste at outside house approximately twice as much as that at inside house. Per capita food waste generation rates from several sources were determined as follows; 166~215g/capita day at municipalities, 400g/visitor day at a first class hotel, 170g/student day at a university restaurant. Food waste generation from restaurant was strongly dependant upon it's level or quality; 670g/capita day at the high level restaurant, 190g/capita day at the middle class and 60 g/capita day at the lower class restaurant. The food waste reduction rate in a In situ fermentor showed 30~40g/kg day.