• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.560-566
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• 1998

The bacteriocin produced by Lactobacillus sp. GM7311 showed strong inhibitory activity against the growth of three Gram positive bacteria, Listeria monocytogenes, Bacillus subtilis, and Staphylococcus aureus. When the bacteriocin was added to the culture at different phases, viable cells of all of the tested strains were decreased, although the most inhibited phase was different. Thereby, when the bacteriocin $(100\;Bu/m{\ell})$ was added to exponential and stationary phase of L. monocytogenes, the rapid reduction of viable cell counts occured. And, in the case of B. subtilis, the highest inhibitory effect occured at lag phase and mid-exponential phase by the addition of the bacteriocin under same condition as mentioned above. Also, we can observe the accelerated reduction of survivors counts for the all of the phase except stationary phase in the S. auresus. Transmission electron microscopic observation of L. monocrogenes and B. subtilis treated with bacteriocin revealed apparent Iysis of the cell wall and excretion of the cell contents, indicating bacteriolysis. Also, the amino acids and fatty acids compositions were different from controls. However, the Iysis of cell wall didn't occur in S. aureus, though the cytoplasmic materials were reduced. This result indicates that the bacteriocin inhibits the synthesis of nuclear materials such as DNA, RNA and proteins.

• Journal of Microbiology and Biotechnology
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• v.27 no.10
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• pp.1820-1826
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• 2017

Lipoteichoic acid (LTA), a cell wall component of gram-positive bacteria, is recognized by Toll-like receptor 2, expressed on certain mammalian cell surfaces, initiating signaling cascades that include nuclear factor kappa-light-chain-enhancer of activated B cells (NF-${\kappa}B$) and mitogen-activated protein kinase. There are many structural and functional varieties of LTA, which vary according to the different species of gram-positive bacteria that produce them. In this study, we examined whether LTA isolated from Staphylococcus aureus (aLTA) affects the expression of junction proteins in keratinocytes. In HaCaT cells, tight junction-related gene expression was not affected by aLTA, whereas adherens junction-related gene expression was modified. High doses of aLTA induced the phosphorylation of extracellular signal-regulated protein kinases 1 and 2, which in turn induced the epithelial-mesenchymal transition (EMT) of HaCaT cells. When cells were given a low dose of aLTA, however, NF-${\kappa}B$ was activated and the total cell population increased. Taken together, our study suggests that LTA from S. aureus infections in the skin may contribute both to the outbreak of EMT-mediated carcinogenesis and to the genesis of wound healing in a dose-dependent manner.

• Journal of Ginseng Research
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• v.25 no.1
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• pp.53-58
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• 2001

To clarify a significant difference between red-colored phenomena (RCP) and microbes isolated from rhizosphere soil of healthy ginseng (HES) and red-colored ginseng (RCS), we have examined growth and cellulase activities of the microbes according to pH variation and iron status. The soil microbes could not grow at pH 3.0 on the YEB medium. The growth of bacterium isolated from RCG at pH from 5.0 to 9.0 showed small differences and the growth of bacterium HES was lower than that of others. The growth of bacteria from RCS and surface soil (SUS) at pH 5.0 were also lower than that of pH 7.0 and pH 9.0. However, the bacteria isolated from red-colored ginseng (RCG) and RCS are able to grow on the medium contained 2 mM Fe$\^$3+/ at pH 3.0. Furthermore, the growth of bacterium from RCG increased about two times in the medium contained iron at pH 7.0 compared with minus iron. The cellulase activity of isolated bacteria increased two times in the medium contained 2 mM Fe$\^$3+/ compared with minus iron. The activity of extra-cellular cellulase was higher by one hundred times than that of intracellular level. The cellulase activity of the bacterium from RCS at pH 5.0 was higher by two times than that of pH 7.0. Especially, intracellular activity of the bacterium from RCS on the medium contained 2mM Fe$\^$3+/ increased about six to seven times compared with control (minus iron). Also, extra-cellular activity increased about eleven to twelve times compared with control. These results indicate that the soil microbes seem to be related iron redoxidation by proton extrusion and with cell wall digestion by secreted cellulase.

• Environmental Analysis Health and Toxicology
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• v.8 no.3_4
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• pp.7-12
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• 1993

An Actinomycete strain isolated from Mt. Dea-Dun had a strong antifungal activity. The culture brith produced by isolated strain showed only antifungal activity against fungi with the exception of yeast and bacteria. It was heat stable, dissolved in ehtylacetate. The concentrated antifungal agent showed cytotoxicity against HEP-2 and HeLa as tumor cell line, and showed weak cytotoxicity against VERO 36 as normal cell line. Morphological and physiological characteristics were tested with isolated strain. The spore color of isolated strain was gray. It had a short chain and produced brown colored lytic substance in yeast extract-malt agar. The cell wall of isolated strain was composed of meso-DAP, and we suggested it as genus Actinomadura. In the existing of chemical inhibitor, isolated strain grew on the condition of 0.0001% crystal violet, 0.1% phenol, 0.01% sodium azide and 10% sodium chloride. Carbon utilization of isolated strain was shown that glucose, sucrose, manitol and sodium citrate were well utilized.

• Analytical Science and Technology
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• v.30 no.3
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• pp.113-121
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• 2017

Now a day's rise of new antibiotic resistant bacterial strains is a global threat. Ethnic people of India have been employing Aphanamixis polystachya (Wall.) R. Parker wood extract in healing cancerous wounds. The aim of this study was to evaluate the antimicrobial activity and to identify the medicinally potent chemicals in the essential oil extract of A. polystachya. The antibacterial properties of various organic extracts were evaluated against a range of bacteria (gram-positive and gram-negative bacteria) based on the disc diffusion method and GC-MS based analysis for finding active oil extract components. All extracts of A. polystachya leaves showed potential antibacterial activity, notably ethyl acetate, while petroleum ether extracts revealed highly sensitive activity against all tested bacteria (zones of inhibition ranging from 8.83 to 11.23 mm). In addition, the petroleum ether extract had the lowest MIC value (32 to $256{\mu}g/mL$) against E. coli, S. lutea, X. campestris, and B. subtilis bacteria. The major compounds detected in oil [${\beta}$-elemene (16.04 %), ${\beta}$-eudesmol (12.78 %), ${\beta}$-caryophyllene (19.37 %), ${\beta}$-selinene (11.32 %), elemol (5.76 %), and ${\alpha}$-humulene (5.68 %)] are expected to be responsible for the potent antimicrobial activity. The results of this study offer valuable insights into the potent role of A. polystachya essential oil extract in pharmaceutical and antibiotic research.

• Journal of Conservation Science
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• v.23
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• pp.67-72
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• 2008

This study was conducted to examineboth the type of wood decay and the degree of degradation for the waterlogged woods (Alnus spp. and Fraxinus spp., about 5,700~5,900 year old), which were excavated at Higokri, Pyungteak in the west-coastal region of Korea. The transmission electron microscope (TEM) observation indicated the degradations by soft rot and bacteria were common in both woods. Erosion bacteria attacked gradually and irregularly from the secondary layer to compound middle lamella and often produced the cavity which was similar to soft-rot cavity but much smaller ones. Tunneling bacteria decomposed mainly $S_2$ layer. Though of highly degraded walls, the cells almost kept the original form with intact lignin-rich middle lamella, which were saturated by water. No marine borer's trace indicated that the sealine rise in the western coast of Korean peninsula during the climate optimum period in the holocene might not be high enough to submerge the Higokri area which locates about 2 km from the present sealine.

• Biomedical Science Letters
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• v.15 no.3
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• pp.257-260
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• 2009

Toll-like receptors (TLRs) recognize molecular structures derived from microbes including bacteria, viruses, yeast, and fungi. TLRs have emerged as a major signaling component of the mammalian host defense. TLR4 is a member of the Toll family that senses lipopolysaccharide (LPS), a cell wall component of gram negative bacteria. LPS recognition by TLR4 requires an additional accessory molecule, MD-2. LPS induces the activation of NF-${\kappa}B$ and IRF3 through MyD88 or TRIF-dependent pathways. The activation of NF-${\kappa}B$ leads to the induction of inflammatory gene products including cytokines and cyclooxygenase-2 (COX-2). This study was carried out to investigate the anti-inflammatory effects of oak wood vinegar. Oak wood vinegar inhibits the NF-${\kappa}B$ activation and COX-2 expression induced by LPS. These results provide new ideas to understand the mechanism of oak wood vinegar for its anti-bacterial and anti-inflammatory activities.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.135-135
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• 2008

Various biosensors were evaluated for identifying and detecting foodborne pathogens in a rapid and effective manner. First, five strains of Escherichia coli and six strains of Salmonella were identified using Fourier transform infrared spectroscopy and a statistical program. For doing this, lipopolysaccharides (LPSs) and outer membrane proteins (OMPs) were extracted from a cell wall of each bacterial strain. As a result, each strain was identifed at the level of 97% for E. coli and 100% for Salmonella. Second, E. coli O157:H7, S. Enteritidis, and Listeria monocytogenes were identified by multiplex PCR products from four specific genes of each bacteria using a capillary electrophoresis (CE). Also, ground beef for E. coli O157:H7, lettuce for S. Enteritidis, and hot dog for L. monocytogenes were used to determine the possibility of detecting pathogens in foods. Foods inoculated with respective pathogen were cultivated for six hours and multiplex PCR products were obtained and assessed. The minimum detection levels of tested bacteria were <10 cells/g, <10 cells/g, and $10^4$ cells/g for E. coli O157:H7, S. Enteritidis, and L. monocytogenes, respectively. Third, it was possible to detect S. Typhimurium in a pure culture and lettuce by a bioluminescence-based detection assay using both recombinant bacteriophage P22::luxI and a bioluminescent bioreporter. In addition, bacteriophage T4 was quantitatively monitored using E. coli including luxCDABE genes.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.759-771
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• 2023

Plant growth-promoting rhizobacteria (PGPR) are naturally occurring bacteria that intensively colonize plant roots and are crucial in promoting the crop growth. These beneficial microorganisms have garnered considerable attention as potential bio-inoculants for sustainable agriculture. PGPR directly interacts with plants by providing essential nutrients through nitrogen fixation and phosphate solubilization and accelerating the accessibility of other trace elements such as Cu, Zn, and Fe. Additionally, they produce plant growth-promoting phytohormones, such as indole acetic acids (IAA), indole butyric acids (IBA), gibberellins, and cytokinins.PGPR interacts with plants indirectly by protecting them from diseases and infections by producing antibiotics, siderophores, hydrogen cyanide, and fungal cell wall-degrading enzymes such as glucanases, chitinases, and proteases. Furthermore, PGPR protects plants against abiotic stresses such as drought and salinity by producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and modulating plant stress markers. Bacteria belonging to genera such as Bacillus, Pseudomonas, Burkholderia, Pantoa, and Enterobacter exhibit multiple plant growth-promoting traits, that can enhance plant growth directly, indirectly, or through synergetic effects. This comprehensive review emphasizes how PGPR influences plant growth promotion and presents promising prospects for its application in sustainable agriculture.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.189-197
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• 1998

Hyeroxyapatite(HAp) which has good biocompatibility was made by Wet Chemical Process. The surface of Ti-6Al-4V, coated with HAp by lon Beam Assisted Deposition (IBAD), was treated with 5ppm, 10ppm, 20ppm, and 100ppm of $AgNO_3$ solution. In this Ag impregnation process, $Ca^{2+}$ of HAp was substituted with $Ag^+$ of $AgNO_3$. In this study, the antimicrobial effect and biocompatibility of Ti-6Al-4V alloy which was coated with Ag-HAp were examined. The antimicrobial test was carried out with two kinds of bacteria(P. Aeruginosa, S. Epidermidis), which are highly infectious in a transplanting operation of implant materials. As a result of the test, it was observed that Ti-6Al-4V alloy which was treated by 20ppm of $AgNO_3$ solution has good biocompatibility. In order to observe the antimicrobial mechanism of $Ag^+$, E. coli which is the most common bacterium was treated by Ag-HAp. Then cell morphology of E. coli was observed by the transmission electron microscope(TEM). The destruction of cell wall and cytoplasm of E. coil were observed. A black spot appeared in the cytoplasm was analyzed by energy dispersive analysis X-ray (EDAX) and it showed a small amount of $Ag^+$. Thus, it was proved that $Ag^+$ destroys bacteria effectively and Ti-6Al-4V alloy which was impregnate with Ag ion show antimicrobial effect on infection bacteria.