• Microbiology and Biotechnology Letters
• /
• v.46 no.2
• /
• pp.91-101
• /
• 2018

The aim of this study was to transfer the 18.5 kb gene clusters coding for 17 genes from Lactobacillus rhamnosus to Lactococcus lactis subsp. cremoris MG1363 in order to determine the effect of host on exopolysaccharide (EPS) production and to provide a model for studying the phosphorylation of proteins which are proposed to be involved in EPS polymerization. Lactobacillus rhamnosus RW-9595M and ATCC 9595 have 99% identical operons coding for EPS biosynthesis, produced different amounts of EPS (543 vs 108 mg/l). L. lactis subsp. cremoris MG1363 transformed with the operons from RW-9595M and ATCC 9595 respectively, produced 326 and 302 mg/l EPS in M17 containing 0.5% glucose. The tyrosine protein kinase transmembrane modulator (Wzd) was proposed to participate in regulating chain elongation of EPS polymers by interacting with the tyrosine protein kinase Wze. While Wzd was found in phosphorylated form in the presence of the phosphorylated kinase (Wze), no phosphorylated proteins were detected when all nine tyrosines of Wzd were mutated to phenylalanine. Lactococcus lactis subsp. cremoris could produce higher amounts of EPS than other EPS-producing lactococci when expressing genes from L. rhamnosus. Phosphorylated Wzd was essential for the phosphorylation of Wze when expressed in vivo.

• KSBB Journal
• /
• v.26 no.1
• /
• pp.33-40
• /
• 2011

Anti-diabetic effect of the exopolysaccharides (EPS) produced from submerged mycelial culture of Cordyceps sinensis (Cs) was studiedin a type II diabetic animal model (C57BL/6J ob/ob). This study was designed to determine whether Cs-EPS improves clinical symptoms of type II diabetes in ob/ob mice. After Cs-EPS treatment at doses of 200 mg/kg body weight, the fasting blood glucose levels decreased by 47% after 7 weeks compared with those of the control mice. According to the oral glucose tolerance test, the glucose levels recovered its baseline after 120 min in Cs-EPS-treated mice, although the blood glucose levels increased significantly after 30 min. On the other hand, the control group (not-treated) did not recovered its initial level of glucose after 120 min. Furthermore, food intake, body weight, total plasma cholesterol and triglyceride concentrations in ob/ob mice treated with Cs-EPS were significantly decreased, compared with those in control ob/ob mice. Cs-EPS treatment increased significantly the plasma insulin level and the expression of leptin mRNA in adipose tissue of Cs-EPS-treated ob/ob mice. From these results, it is demonstrated that Cs-EPS could be effective for regulating normal blood glucose levels by increasing the amounts of plasma insulin and leptin expression in ob/ob mice, indicating that this compound could be a candidate material as a dietary supplement to control hyperglycemia in patients suffering from type II diabetes.

• Journal of the Korean Society for Precision Engineering
• /
• v.34 no.1
• /
• pp.35-39
• /
• 2017

We used a construction method using a CNC milling machine, where free-formed molds were made by cutting EPS (Expanded PolyStyrene) foam with the CNC machine, to build free-formed buildings. CNC milling is off-the-shelf technology that can easily cut EPS foam; however its production cost is too high and the time to manufacture an EPS mold is too long. This paper proposes a novel cutting machine with a fast and cost effective mechanism to manufacture EPS concrete molds. Our machine comprises a cutter and Cartesian coordinate type moving mechanism, where the cutter cuts EPS foam using a hotwire in the shape of '$\sqcap$' and is capable of adjusting its cutting angle in real-time while keeping its cutting width. We proved through cutting experiments on the CNC machine that cutting time was greatly shortened compared to the conventional method and that the resulting concrete mold satisfied manufacturing precision.

• Microbiology and Biotechnology Letters
• /
• v.23 no.3
• /
• pp.269-274
• /
• 1995

For the screening of a new functional exopolysaccharide, sugar composition and rheological properties of exopolysaccharide produced from Xanthomonas sp. EPS-1 were investigated. The average molecular weight of exopolysaccharide was determined to be approximately 2.l $\times$ 10$^{6}$ dalton. The new exopolysaccharide EPS-1 was composed of mannose, glucose, galactose and gluco- samine. IR analysis showed that the exopolysaccharide EPS-1 was assumed to be polymer with carbohydrates. NMR analysis showed that exopolysaccharide EPS-1 was presumed to be 4 units of sugar and trace of CH$_{3}$ group. Exopolysaccharide EPS-1 solution showed a characteristic of non-Newtonian fluid properties. At the concentration of 1.0%, the consistency index and the flow behavior index were shown at 10.8352 poise-sec and 0.4419, respectively. All dispersions were pseudoplastic fluids described accurately by Power-law model. Exopolysaccharide EPS-1 was highly viscous at low concentration, with good stability over a wide range of pH 5 to 13. The excellent compatibility of exopolysaccharide EPS-1 was represented with salts such as sodium chloride.

• The Plant Pathology Journal
• /
• v.39 no.5
• /
• pp.417-429
• /
• 2023

Ralstonia solanacearum species complex (RSSC) is a soil borne plant pathogen causing bacterial wilt on various important crops, including Solanaceae plants. The bacterial pathogens within the RSSC produce exopolysaccharide (EPS), a highly complicated nitrogencontaining heteropolymeric polysaccharide, as a major virulence factor. However, the biosynthetic pathway of the EPS in the RSSC has not been fully characterized. To identify genes in EPS production beyond the EPS biosynthetic gene operon, we selected the EPS-defective mutants of R. pseudosolanacearum strain SL341 from Tn5-inserted mutant pool. Among several EPSdefective mutants, we identified a mutant, SL341P4, with a Tn5-insertion in a gene encoding a putative NDP-sugar epimerase, a putative membrane protein with sugar-modifying moiety, in a reverse orientation to EPS biosynthesis gene cluster. This protein showed similar to other NDP-sugar epimerases involved in EPS biosynthesis in many phytopathogens. Mutation of the NDP-sugar epimerase gene reduced EPS production and biofilm formation in R. pseudosolanacearum. Additionally, the SL341P4 mutant exhibited reduced disease severity and incidence of bacterial wilt in tomato plants compared to the wild-type SL341 without alteration of bacterial multiplication. These results indicate that the NDP-sugar epimerase gene is required for EPS production and bacterial virulence in R. pseudosolanacearum.

• Microbiology and Biotechnology Letters
• /
• v.34 no.3
• /
• pp.196-203
• /
• 2006

Three slime-forming lactic acid bacteria were isolated from Kimchi and shown to produce viscous exopolysaccharides (EPS) in sucrose media. The isolated strains, GJ2, C3 and C11, were identified as Leuconostoc kimchii, Leuconostoc citreum and Leuconostoc mesenteroides, respectively, by examining their metabolic characteristics and determining their 16S rDNA sequences. Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 exhibited high viability (maintained initial viable cell count of $10^8$ CFU/ml) in 0.05 M sodium phosphate buffer (pH 3.0) for 2 h, in artificial gastric juice for 2 h and in 0.3% oxgall for 24 h. When tested, Leu. kimchii GJ2, in particular, displayed antimicrobial activity against pathogenic microorganisms. Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 produced 21.49 g/l, 16.46 g/l and 22.98 g/l EPS, respectively, in sucrose (5%) medium. The amount of purified EPS extracted from Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 was 14.61 g/l, 7.73 g/l and 4.77 g/l, respectively. Although the EPS produced by Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 differed in viscosity, TLC and HPLC analysis revealed that each contained only one type of monosaccharide, glucose. The average molecular mass of EPS produced by Leu. kimchii GJ2 was 306,606 Da.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.29 no.3
• /
• pp.132-139
• /
• 2019

EPS (expanded polystyrene) is one of the most used building materials for insulation that is favored by its excellent heat insulation, economical efficiency and lightweight characteristics. However, EPS is vulnerable to the fire and producing large amount of toxic gases in case of fire. Therefore, ultra-lightweight geopolymer which can replace EPS is fabricated by using IGCC (integrated gasification combined cycle) fused slag and Si sludge as raw materials and the possibility of replacement on ultra-lightweight geopolymer for EPS as an insulation building material was evaluated in this study. Ultra-lightweight geopolymer can be fabricated with the pulverized IGCC fused slag having low carbon content and density, compressive strength, thermal conductivity were $0.064g/cm^3$, 0.04 MPa, and 0.072 W/mK, respectively. The thermal conductivity of ultra-lightweight geopolymer is 1.5~2.0 times higher than that of EPS suggested in the KS M 3808; however, the thermal conductivity value of geopolymer is meaningful and competitive to that of EPS in the market. Therefore, ultralightweight geopolymer can be applicable to the building material for thermal insulation purpose and have an enough possibility to replace EPS in the future because it is not only much safer than EPS in case of fire but also it can be fabricate by using waste materials from the industry.

• Journal of the Korean Vacuum Society
• /
• v.14 no.1
• /
• pp.35-39
• /
• 2005

In the UV-NIL process using an elementwise patterned stamp (EPS), which includes channels formed to separate each element with patterns, low-viscosity resin droplets with a nano-liter volume are dispensed on all elements of the EPS. Following pressing of the EPS, the EPS is illuminated with UV-light to cure the resin; and then the EPS is separated from several thin patterned elements on a wafer. Experiments on UV-NIL were performed on an EVG620-NIL. 50 - 100nm features of the EPS with 3m channels were successfully transferred to 4 in. wafers. Especially, the wafer deformation during imprint was analyzed using the finite element method (FEM) in order to study the effect of the wafer deformation on the UV-NIL using EPS.

• Geotechnical Engineering
• /
• v.12 no.5
• /
• pp.127-136
• /
• 1996

Recently, EPS which has unit weight of only 20~30kg/m3, is used for acquiring the safety of settlement and bearing capacity, In Korea, EPS was first used in 1993 as backfill material for abutment that was constructed on soft ground in Inchon. Since then EPS has been used increasingly as backfill material. However, adequate modelling has not yet been proposed for the prediction of the behavior of EPS. Only it's design strength was proposed as the results of unconfined strength and creep test. Accordingly this paper executed triaxial compression test on EPS with various density and confining pressure. Through the analysis of test data the behavior of EPS for strainstress, tangential modulus and poisson's ratio can be expressed in functions with parameters of density and confining pressure of EPS. From these results, this paper proposed a nonliner model describing the behavior of EPS.

• Ecology and Resilient Infrastructure
• /
• v.3 no.4
• /
• pp.215-220
• /
• 2016

A new immobilization technique of nanoscale $TiO_2$ powder to expanded polystyrene (EPS) balls with temperature-controlled melting method was developed, and the photocatalytic activity of $TiO_2$ powder-embedded EPS balls were evaluated using methylene blue (MB) solution under ultraviolet irradiation (${\lambda}=254nm$). Based on the scanning electron microscope (SEM) images and associated energy-dispersive X-ray spectroscopy (EDX) analysis, the components of the intact EPS balls were mainly carbon and oxygen, whereas those of $TiO_2$-immobilized EPS balls were carbon, oxygen, and titanium, indicating that relatively homogenous patches of $TiO_2$ and glycerin film were coated on the surface of EPS balls. Based on the comparison of degradation efficiencies of MB between intact and $TiO_2$-immobilized EPS balls under UVC illumination, the degradation efficiencies of MB can be significantly improved using $TiO_2$-immobilized EPS balls, and surface reactions in heterogeneous photocatalysis were more dominant than photo-induced radical reactions in aqueous solutions. Thus, $TiO_2$-immobilized EPS balls were found to be an effective photocatalyst for photodegradation of organic compounds in aqueous solutions without further processes (i.e., separation, recycling, and regeneration of $TiO_2$ powder). Further study is in progress to evaluate the feasibility for usage of buoyant $TiO_2$-immobilized EPS to inhibit the excessive growth of algae in rivers and lakes.