• Journal of Environmental Science International
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• v.14 no.12
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• pp.1163-1170
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• 2005

The microbial adsorption characteristics of two different media for biological treatment were studied using attached diverse microbes onto activated carbon and ceramic. The results in the experiments of the characteristics of physical adhesion on two different media with addition of high and low concentrated substrate in the culture were observed that the efficient of adhesion onto F-400 activated carbon was higher over that of ceramic due to the surface area of media. The irradiation treatment by ultrasonication with 400 W power and 3 min retention time on the media without addition substrate conditions and subsequent mixing throughly the culture showed the highest efficiency of cell detachment on the media. Three different microbes, P. ovalis, A calcoaceticus, and B. subtillis were used for the study of the characteristics of microbial adhesion on the media. p ovalis showed the highest adhesion capability while B. subtillis showed the lowest capability adhesion onto media either addition of substrate in the culture. The mixed bacterial culture showed $10\%$ lower removal efficiency of DOC in the low concentrated substrate culture compared to the single pure culture. Whileas, it did not show significant difference between two cultures at high concentrated substrate. It was also observed same population density of microorganism by counting of microbes adhered to microbial media with an ultrasound treatment.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.225-230
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• 2004

A plasminogen kringle domain 1 to 3, rKl-3, was expressed in Escherichia coli under the control of T7 promoter. For the cost-effective production of rKl-3, the induction process was analyzed and optimized. Induction characteristics with lactose were analyzed in terms of induction time and inducer concentration in various culture conditions including batch and high-cell-density fed-batch cultures. In the fed-batch culture, the induction around 6 h after initiation of the DO-stat fed-batch culture resulted in the highest expression level of rKI-3 among the induction points examined. The highest demand of oxygen at this point was crucial for the maximum expression level of rKI-3. As the lactose concentration increased, the expression level also increased, though the expression level showed a plateau above a concentration of 14 mM of lactose. Lactose acted less specifically than IPTG since most of it was hydrolyzed to glucose and galactose. However, using lactose, the cell growth and the maximum expression level of rKl-3 increased by 20% and 24%, respectively, compared with those using IPTG in the fed-batch culture. The lactose seemed to be hydrolyzed by intracellular and extracellular $\beta$-galactosidase liberated by cell lysis at the same time. Residual concentration of glucose was maintained to a a limit of detection by high performance liquid chromatography, and galactose was not consumed by the host strain Escherichia coli BL2l(DE3).

• KSBB Journal
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• v.9 no.2
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• pp.211-223
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• 1994

In fermentations with a 4-liter stirred tank bioreactor, a better than two-fold enhancement of the gas-liquid mass transfer coefficient$(k_La)$ in the celite-immobilized fungal cultures of Tolypocladium in flatum over the parallel conventional free-cell was observed at identical biomass concentrations, despite the higher specific oxygen uptake rate of the immobilized fungi during exponential growth. As a result oxygen sufficient conditions, i. e., dissolve oxygen(D.O.) concentrations exceeding 75% air saturation, could be maintained throughout exponential growth period of the immobilized culture, in contrast to the suspended fungal culture, whose D.O. levels fell below 50% air saturation. A linear monotonic dependence of $k_La$ upon impeller agitaion rate was found for both immobilized and conventional cultivation modes over a range of 250 to 550rpm, the slope being a function of biomass concentration for the free but not for the immobilized cell system In contrasts oxygen transfer rate was a much weaker function of aeration rate up to about 2.5 vvm for both culture configurations. Above this level, aeration rate had no further effect on the mass transfer. In addition, the immobilized cultures sustained good morphological and physiological states, leading to almost two times higher cyclosporln A (CyA) productivity overt the parallel free cell system. These experiments suggest that the celite-immobilized fungal system in a stirred tank reactor has considerable promise for scaling up cyclosporin A production in terms of high-density cultivation.

• Microbiology and Biotechnology Letters
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• v.29 no.4
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• pp.227-233
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• 2001

To maximize astaxanthin (3,3'-dihydroxy-$\beta\beta$'carotene-44'-dione) production by high density Haematococcus pluvialis cultures, various, media were examined Among tested media, \`Hong Kong Medium and Modified Bolds Basal Medium showed the best result for cell growth ( $2.0$\times$10^{ 6}$cells /mL) and for astaxanthin content per cell (9.7 mg astaxanthin mg/g cell), respectively, Maximum astasanthin concentration of 6.1mL was obtained at pH 7.5, $20^{\circ}C$~$25^{\circ}C$ Deficiencies of nitrogen source($NaNO_3$ and proteose-peptone) found to simulate astaxanthin formation Relatively low light inten- sity of $60\mu$E ($\m^2$s) was sutiable for vegetative cell growth while higher light intensity was required for higher astaxanthin accumulation.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.3
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• pp.167-173
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• 2011

The Effects of external resistance on electrical properties such as current density, power density and coulombic efficiency were investigated in two-chamber type MFCs using a ferricyanide as reducing agent. A stable electricity was produced when a constant time elapsed after innoculation of mixed cultures into the anode compartment; voltages from 0.13 to 0.16 V was measured at $50{\Omega}$ of external resistance. When the external resistance was increased, the current density decreased and the power density rapidly increased and then slowly decreased. Big variation of electrical properties was observed in high-current density region due to the concentration loss related with substrate consumption in repeated experiments changing the external resistance. The maximum power density ($175.8mW/m^2$) and coulombic efficiency (46.1%) were obtained at $100{\Omega}$ of the external resistance which is nearest with the internal resistance ($134{\Omega}$) of MFC system.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.2
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• pp.100-107
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• 2004

Schwann cell, one of important components of peripheral nervous system, interact with neurons to mutually support the growth and replication of embryonal nerves and to maintain the different functions of adult nerves. The Ara-C, known as an antimitotic agent, have been used to have high effectiveness in eliminating fibroblasts during Schwann cell culture period. This enrichment effect is also known to be cummulative with each successive pulse of Ara-C applied and is due to a progressive loss of fibroblasts. But the cytotoxicity by Ara-C is also cummulative and noticeable over the period. To determine the most effective application time and interval of Ara-C in the Schwann cell culture, we observed the Schwann cell purity and density with the Ara-C treatment in plain and three-dimensional culture from dorsal root ganglion of new born rat. By culturing dispersed dorsal root ganglia, we can repeatedly generate homogenous Schwann cells, and cellular morphology and cell count with mean percentages were evaluated in the plain culture dishes and in the immunostainings of S-100 and GFAP in the three-dimensional culture. The Ara-C treated cultures showed a higher Schwann cell percentage ($31.0%{\pm}8.09%$ in P4 group to $65.5%{\pm}24.08%$ in P2 group), compared with that obtained in the abscence of Ara-C ($17.6%{\pm}6.03%$) in the plain culture after 2 weeks. And in the three-dimensional culture, S-100 positive cells increased to $56.22%{\pm}0.67%$ and GFAP positive cells to $66.46%{\pm}1.83%$ in G2 group (p<0.05), higher yield than other groups with Ara-C application. Therefore, we concluded that the Ara-C treatment is effective for the proliferation of Schwann cells contrast to the fibroblasts in vitro culture, and the first application after 24 hours from cell harvesting and subsequent 2 pulse treatment (P2 group in plain culture and G2 group in three-dimensional culture) was more effective than other application protocols.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.1
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• pp.42-51
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• 2006

Schwann cell, one of important components of peripheral nervous system, interact with neurons to mutually support the growth and replication of embryonal nerves and to maintain the different functions of adult nerves. The Ara-C, known as an antimitotic agent, have been used to have high effectiveness in eliminating fibroblasts during Schwann cell culture period. This enrichment effect is also known to be cummulative with each successive pulse of Ara-C applied and is due to a progressive loss of fibroblasts. But the cytotoxicity by Ara-C is also cummulative and noticeable over the period. To determine the most effective application time and interval of Ara-C in the Schwann cell culture, we observed the Schwann cell purity and density with the Ara-C treatment in plain and three-dimensional culture from dorsal root ganglion of new born rat. By culturing dispersed dorsal root ganglia, we can repeatedly generate homogenous Schwann cells, and cellular morphology and cell count with mean percentages were evaluated in the plain culture dishes and in the immunostainings of S-100 and GFAP in the three-dimensional culture. The Ara-C treated cultures showed a higher Schwann cell percentage (31.0%${\pm}$8.09% in P4 group to 65.5%${\pm}$24.08% in P2 group), compared with that obtained in the abscence of Ara-C (17.6%${\pm}$6.03%) in the plain culture after 2 weeks. And in the three-dimensional culture, S-100 positive cells increased to 56.22%${\pm}$0.67% and GFAP positive cells to 66.46%${\pm}$1.83% in G2 group (p<0.05), higher yield than other groups with Ara-C application. Therefore, we concluded that the Ara-C treatment is effective for the proliferation of Schwann cells contrast to the fibroblasts in vitro culture, and the first application after 24 hours from cell harvesting and subsequent 2 pulse treatment (P2 group in plain culture and G2 group in three-dimensional culture) was more effective than other application protocols.

• Microbiology and Biotechnology Letters
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• v.29 no.4
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• pp.206-211
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• 2001

In order to overexpress constitutively the Kluyveromyces marxianus exoinulinase gene (INUI) in Saccharomyces cerevisiae, four episomal expression systems employing GAPDH, ADHI, PGK and ENOI promoters were constructed as p YIGP aADHI -INU, pPGK-INU, and pENOI- INU plasmids respectively, When S cereviais transformants harboring each plasmid were batchwisely cultivated in the fermentor containing 5% glucose medium no significant differences in the cell growth are observed How- ever the experession level of exoinulinase and plasmid stability showed a strong dependency on the promoter employed. The expression levels of exoinulinase were about 1.70 unit/ml for GAPDH promoter 1.67 unit/ml for PGK promoter, 1.29 unit /ml for ADH1 promoter, and 0.80 unit/ml for ENOl promoter. The plasmid stabilites were maintaines above 80% in all experession systems. except the GAPDH promoter system of 55%, Based on the plas- mid stability and expression level of exoinulinase the ADHl and PGK promoter system were selected for the fed - batch culture to overproduce exoinulinase By the intermittent feeding of yeast extract and glucose, both promoter systems gave the cell concentration of about 30 g-dry cell weight/1 byt the maximal exoinulinase activity of 3.70 unit/ml and plasmid stability of 96% in the ADH1 promoter were higher than those (2.70 unit/ml, 80%) of PGK sys- tem Taking into account the plasmid stability and extended culture time the ADH1 promoter systems would be the most feasible expression systems for the constitutive overproduction of exoinulinase through high cell-density fed- batch cultures using non-selective rich medium.

• 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.

• KSBB Journal
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• v.25 no.2
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• pp.142-154
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• 2010

The protein-bound innerpolysaccharides (IPS) produced by suspended mycelial cultures of Inonotus obliquus have promising potentials as an effective antidiabetic as well as an immunostimulating agents. To enhance IPS production, intensive strain improvement process should be carried out using large amount of UV-mutated protoplasts. During the whole strain-screening process, the stage of solid growth-culture was found to be the most time-requiring step, thus preventing rapid screening of high-yielding producers. In order to reduce the cell growth period in the solid growth-stage, therefore, solid growth-medium was optimized using the statistical methods such as (i) Plackett-Burman and fractional factorial designs (FFD) for selecting positive medium components, and (ii) steepest ascent (SAM) and response surface (RSM) methods for determining optimum concentrations of the selected components. By adopting the medium composition recommended by the SAM experiment, significantly higher growth rate was obtained in the solid growth-cultures, as represented by about 41% larger diameter of the cell growth circle and higher mycelial density. Sequential optimization process performed using the RSM experiments finally recommended the medium composition as follows: glucose 25.61g/L, brown rice 12.53 g/L, soytone peptone 12.53 g/L, $MgSO_4$ 5.53 g/L, and agar 20 g/L. It should be noted that this composition was almost similar to the medium combinations determined by the SAM experiment, demonstrating that the SAM was very helpful in finding out the final optimum concentrations. Through the use of this optimized medium, the period for the solid growth-culture could be successfully reduced to about 8 days from the previous 15~20 days, thus enabling large and mass screening of high producers in a relatively short period.