• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1444-1452
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• 2019

The conventional prophylactic vaccines for human papillomavirus (HPV) efficiently prevent infection with high-risk HPV types, but they do not promote therapeutic effects against cervical cancer. Previously, we developed HPV16 E7-expressing Lactobacillus casei (L. casei-E7) as a therapeutic vaccine candidate for cervical cancer, which induces antitumor therapeutic effects in a TC-1 murine cancer model. To improve the therapeutic effect of L. casei-E7, we performed co-treatment with poly-gamma-glutamic acid (${\gamma}-PGA$), a safe and edible biomaterial naturally secreted by Bacillus subtilis. We investigated their synergistic effect to improve antitumor efficacy in a murine cancer model. The treatment with ${\gamma}-PGA$ did not show in vitro cytotoxicity against TC-1 tumor cells; however, an enhanced innate immune response including activation of dendritic cells was observed. Mice co-administered with ${\gamma}-PGA$ and L. casei-E7 showed significantly suppressed growth of TC-1 tumor cells and an increased survival rate in TC-1 mouse models compared to those of mice vaccinated with L. casei-E7 alone. The administration of ${\gamma}-PGA$ markedly enhanced the activation of natural killer (NK) cells but did not increase the E7-specific cytolytic activity of $CD8^+$ T lymphocytes in mice vaccinated with L. casei-E7. Overall, our results suggest that oral administration of ${\gamma}-PGA$ induces a synergistic antitumor effect in combination with L. casei-E7.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.449-454
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• 2008

Some pretreatment methods have been proposed to enhance the biodegradability and to shorten the hydrolysis reaction time. By means of efficient pretreatment the suspended solids (SS) can be made of better accessible for the anaerobic bacteria. There are several ways how this can be accomplished, which include biological, mechanical, thermal, and chemical methods. For the sludge solubilization using the cavitation phenomenon, we have tried to develop a pretreatment process consisted of a reactor and pumps. The objectives of this study were to develop a advanced wastewater treatment consisted of IABR and the cavitation with PGA. The most effective removal for organic matter and nutrients were occured when both cavitation pretreatment and ${\gamma}$-PGA were applied at the IABR process. Only small portion of ${\gamma}$-PGA at a rate of 1.38mg/L, was enough to improve sedimentation ability, SS removal efficiencies, and sludge volume reduction. After the sludge solubilization by the cavitation, SCOD increased to 193% and SS decreased to 36%. The removal ratio of BOD was 94.5%, T-N removal ratio was 85.5% and T-P removal ratio was 84.9%. The combination process of the IABR with the cavitation and PGA addition seems to be very effective alternative wastewater treatment process.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1061-1070
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• 2019

In the present study, the optimization of poly(${\gamma}$-glutamic acid) (${\gamma}$-PGA) production by Bacillus sp. FBL-2 was studied using a statistical approach. One-factor-at-a-time method was used to investigate the effect of carbon sources and nitrogen sources on ${\gamma}$-PGA production and was utilized to select the most significant nutrients affecting the yield of ${\gamma}$-PGA. After identifying effective nutrients, response surface methodology with central composite design (CCD) was used to obtain a mathematical model to identify the optimum concentrations of the key nutrients (sucrose, $\text\tiny{L}$-glutamic acid, yeast extract, and citric acid) for improvement of ${\gamma}$-PGA production. The optimum amount of significant medium components appeared to be sucrose 51.73 g/l, $\text\tiny{L}$-glutamic acid 105.30 g/l, yeast extract 13.25 g/l, and citric acid 10.04 g/l. The optimized medium was validated experimentally, and ${\gamma}$-PGA production increased significantly from 3.59 g/l (0.33 g/l/h) to 44.04 g/l (3.67 g/l/h) when strain FBL-2 was cultivated under the optimal medium developed by the statistical approach, as compared to non-optimized medium.

• Journal of Microbiology and Biotechnology
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• v.27 no.5
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• pp.1032-1037
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• 2017

The poly-${\gamma}$-$\small{D}$-glutamic acid (PGA) capsule, a major virulence factor of Bacillus anthracis, provides protection of the bacterium from phagocytosis and allows its unimpeded growth in the host. We investigated crosstalk between murine natural killer (NK) cells and macrophages stimulated with the PGA capsule of Bacillus licheniformis, a surrogate of the B. anthracis capsule. PGA induced interferon-gamma production from NK cells cultured with macrophages. This effect was dependent on macrophage-derived IL-12 and cell-cell contact interaction with macrophages through NK cell receptor NKG2D and its ligand RAE-1. The results showed that PGA could enhance NK cell activation by inducing IL-12 production in macrophages and a contact-dependent crosstalk with macrophages.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4002-4018
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• 2023

An integrated neutron interrogation system has been developed for non-destructive assay of highly-radioactive special nuclear materials, to accumulate knowledge of the method through developing and using it. The system combines a differential die-away (DDA) measurement system for the quantification of nuclear materials and a prompt gamma-ray analysis (PGA) system for the detection of neutron poisons which disturb the DDA measurements; a common D-T neutron generator is used. A special care has been taken for the selection of materials to reduce the background gamma rays produced by the interrogation neutrons. A series of measurements were performed to test the basic performance of the system. The results show that the DDA system can quantify plutonium of as small as 20 mg and it is not affected by intense neutron background up to 1.57 × 10⁷ s^-1 and gamma ray of 4.43 × 10¹⁰ s^-1. The gamma-ray background counting rate at the PGA detector was reduced down to 3.9 × 10³ s^-1 even with the use of the D-T neutron generator. The test measurements show that the PGA system is capable of detecting 0.783 g of boron and about 86.8 g of gadolinium in 30 min.

• KSBB Journal
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• v.8 no.3
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• pp.209-216
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• 1993

For the production of biodegradable polymers from microorganisms a bacterial strain producing a biopolymer was isolated from soil. The bacteriological characteristics of this strain and physicochemical Properties of the biopolymer produced were investigated. The bacterial strain was identified as an alkalophilic Alcaligenes sp. The Purified biopolymer treated with cetylpridinium chloride and acetone was identified as an acidic biopolymer having carboxyl groups and showed strong UV absorbance (at 210nm). The biopolymer was composed of 100% glutamic acid and glutamic acid existed as $\gamma$-polyglutamic acid($\gamma$-PGA) in the form of the $\gamma$-peptide bond. The equivalent weight of this $\gamma$-PGA was estimated about 350, indicating that one acidic fraction per 2.7 residue of $\gamma$-polyglutamic acid existed. The molecular weight was $6.5{\times}10^5$ Daltons.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1170-1178
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• 2008

The cyclopentenone prostaglandins (cyPGs) prostaglandin $A_1$ ($PGA_1$) and 15-deoxy-${\Delta}^{12,14}$-prostaglandin $J_2$ (15d-$PGJ_2$) have been reported to exhibit antiinflammatory activity in activated monocytes/macrophages. However, the effects of these two cyPGs on the expression of cytokine genes may differ. In this study, we investigated the mechanism of action of $PGA_1$ in lipopolysaccharide (LPS)-induced expression of inter leu kin (IL)-10 mRNA in mouse peritoneal macrophages. 15d-$PGJ_2$ inhibited expression of LPS-induced IL-10, whereas $PGA_1$ increased LPS-induced IL-10 expression. This synergistic effect of $PGA_1$ on LPS-induced IL-10 expression reached a maximum as early as 2 h after simultaneous $PGA_1$ and LPS treatment ($PGA_1$/LPS), and did not require new protein synthesis. The synergistic effect of $PGA_1$ was inhibited by GW9662, a specific peroxisome proliferator-activated receptor ${\gamma}(PPAR{\gamma})$ antagonist, and Bay-11-7082, a NF-${\kappa}B$ inhibitor. The extracellular signal-regulated kinases (ERK) inhibitor PD98059 increased the expression of $PGA_1$/LPS-induced IL-10 mRNA, rather than inhibiting the IL-10 expression. Moreover, $PGA_1$ inhibited LPS-induced ERK phosphorylation. The synergistic effect of $PGA_1$ on LPS-induced IL-10 mRNA and protein production was inhibited by p38 inhibitor PD169316, and $PGA_1$ increased LPS-induced p38 phosphorylation. In the case of stress-activated protein kinase/c-Jun $NH_2$-terminal kinase (SAPK/JNK), the SAPK/JNK inhibitor SP600125 did not inhibit IL-10 mRNA synthesis but inhibited the production of IL-10 protein remarkably. These results suggest that the synergistic effect of $PGA_1$ on LPS-induced IL-10 expression is NF-${\kappa}B$-dependent and mediated by mitogen-activated protein (MAP) kinases, p38, and SAPK/JNK signaling pathways, and also associated with the $PPAR{\gamma}$ pathway. Our data may provide more insight into the diverse mechanisms of $PGA_1$ effects on the expression of cytokine genes.

• Macromolecular Research
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• v.13 no.4
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• pp.339-343
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• 2005

Microbial hydrogel was prepared by ${\gamma}-irradiation$ of poly(${\gamma}-glutamic acid$) (PGA) which was produced from Bacillus subtilis BS 62 and it's physico-chemical characteristic was examined. The hydrogel, prepared from 10% PGA with the dose of 48 kGy, was swollen up to 1,370 times of specific water content as dry weight basis. The hydrogels obtained above the dose of 48 kGy appeared to have higher compressive strength but lower specific water content. The period to reach a swelling equilibrium for the hydrogel in deionized water at the temperature range of 4 to $45^{\circ}C$ was about 10 h. The swollen hydrogel was shrunk in ionic solutions with the increase of ionic strength, and the rate of shrinkage was greater in calcium chloride solution than in sodium chloride. Specific water content of the hydrogel was quickly decreased at $80^{\circ}C$, showing a thennally hydrodegradable property.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.942-952
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• 2013

Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(${\gamma}$-glutamic acid) (PGA) has been prepared via a thermally induced phase separation technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the phase separation solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and separation fields.

• Microbiology and Biotechnology Letters
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• v.33 no.3
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• pp.200-206
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• 2005

A bacterium with high productivity of poly-$\gamma$-glutamic acid (PGA) was isolated from the traditional Korean seasoning, ChungKookJang. The 16s ribosomal RNA sequence of isolated strain showed 97.6, 98.9 and $90.3{\%}$ of similarity to those of Bacillus sp. WL-3, Bacillus subtilis; ENV1 and B amy-loliquefaciens (T), respectively. Accordingly, this bacterium was identified as a Bacillus sp. However, some biochemical characteristics of this strain were different from those of B. subtilis: D-xylose fermentation and glycogen utility were negative. Maximum production of PGA was achieved when it was grown aerobically in a culture medium containing glutamic acid ($3{\%}$) and fructose ($4{\%}$) as carbon sources. The volumetric yield of PGA reached up to 27 g/l in the optimum culture medium. These results suggest that the present strain can be applicable for industrial purposes such as a prototype strain for food or cosmetics industry.