• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.293-298
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• 1995

Antimicrobial effect of tea extracts from green tea(steamed, roasted), oolong tea and black tea was investigated. Minimal inhibitory concentration(MIC) of tea extraxcts against 9 well known strains of foodborne pathogenic bacteria such as the Gram positive and Gram negative bacteria was determined at 37$^{\circ}C$. Significant antimicrobial activity was observed in the steamed green tea and the roasted green tea of the water-soluble fraciton, and the steamed green tea of the methanol-soluble fraction, and the steamed green tea, roasted green tea and the oolong tea of the crude catechin fraction. The MIC of these extracts against B. subtillis were 700$\mu\textrm{g}$/ml, 500$\mu\textrm{g}$/ml and 120 $\mu\textrm{g}$/ml, respectively. The crude catechin fraction possessed greater antimicrobial activity than did the other fractions. Among tea extracts, extracts of steamed green tea, roasted green tea and oolong tea showed higher antimicrobial activity than them of black tea. The MIC of the crude catechin fraction obtained from tea extracts against Gram-positive bacteria such as M. Iuteus, B. subtillis and S. mutans were 30~50$\mu\textrm{g}$/ml, 120~240$\mu\textrm{g}$/ml and 120~180$\mu\textrm{g}$/ml, and against Gram-negative bacteri such as e. aerogenes and V. parahaemolyticus were 50~60$\mu\textrm{g}$/ml and 60~70$\mu\textrm{g}$/ml in the broth medium, respectively. Especially, the MIC to Streptococcus mutans which has known as a causative bacteria of a decayed tooth were 120$\mu\textrm{g}$/ml, 140$\mu\textrm{g}$/ml, 180$\mu\textrm{g}$/ml and above 1,000$\mu\textrm{g}$/ml in steamed green tea, roasted green tea, oolong tea and black tea, respectively. Tea extracts had strong growth inhibition activity against foodborne pathogenic and dental bacteria.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.7
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• pp.1052-1061
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• 2019

Objective: This study was conducted to identify duck liver-expressed antimicrobial peptide 2 (LEAP-2) and demonstrate its antimicrobial activity against various pathogens. Methods: Tissue samples were collected from 6 to 8-week-old Pekin ducks (Anas platyrhynchos domesticus), total RNA was extracted, and cDNA was synthesized. To confirm the duck LEAP-2 transcript expression levels, quantitative real-time polymerase chain reaction was conducted. Two kinds of peptides (a linear peptide and a disulfide-type peptide) were synthesized to compare the antimicrobial activity. Then, antimicrobial activity assay and fluorescence microscopic analysis were conducted to demonstrate duck LEAP-2 bactericidal activity. Results: The duck LEAP-2 peptide sequence showed high identity with those of other avian species (>85%), as well as more than 55% of identity with mammalian sequences. LEAP-2 mRNA was highly expressed in the liver with duodenum next, and then followed by lung, spleen, bursa and jejunum and was the lowest in the muscle. Both of LEAP-2 peptides efficiently killed bacteria, although the disulfide-type LEAP-2 showed more powerful bactericidal activity. Also, gram-positive bacteria was more susceptible to duck LEAP-2 than gram-negative bacteria. Using microscopy, we confirmed that LEAP-2 peptides could kill bacteria by disrupting the bacterial cell envelope. Conclusion: Duck LEAP-2 showed its antimicrobial activity against both gram-positive and gram-negative bacteria. Disulfide bonds were important for the powerful killing effect by disrupting the bacterial cell envelope. Therefore, duck LEAP-2 can be used for effective antibiotics alternatives.

• BMB Reports
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• v.41 no.2
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• pp.93-101
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• 2008

The major cell wall components of bacteria are lipopolysaccharide, peptidoglycan, and teichoic acid. These molecules are known to trigger strong innate immune responses in the host. The molecular mechanisms by which the host recognizes the peptidoglycan of Gram-positive bacteria and amplifies this peptidoglycan recognition signals to mount an immune response remain largely unclear. Recent, elegant genetic and biochemical studies are revealing details of the molecular recognition mechanism and the signalling pathways triggered by bacterial peptidoglycan. Here we review recent progress in elucidating the molecular details of peptidoglycan recognition and its signalling pathways in insects. We also attempt to evaluate the importance of this issue for understanding innate immunity.

• Archives of Pharmacal Research
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• v.10 no.4
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• pp.228-231
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• 1987

Studies on the adsorption of four kinds of bacteria, Staphylococcus aureus, Sarcina lutea, Escherichia coli and Serratia marcescens by activated Korean Kaoline have been carried out to innovate utilization as adsosrbent preparations. In connection with particle size and size fraction, the adsorption was examined by colony counting and spectroscopy. Korean kaolin was purified from Hadong white species of preminum grade and three size fractions were derived from passage through BS # 100, #200 and # 325 mesh sieves, respectively. These were activated at $105^{\circ}$or $280^{\circ}$ for three hours and at $550^{\circ}C$ for one hours. The results indicated that the adsorbing power of Korean kaolin was superior for S. aureus and S. lutea, but E. coli and S. marcescens were not adsorbed by clays. The smaller the particle size, the greater was adsorbing power for Gram-positive bacteria. Threre appears to be justification for its investigations as an ingredient in intestinal adsorbent preparations.

• YAKHAK HOEJI
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• v.32 no.4
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• pp.222-229
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• 1988

A series of substituted benzylthioalkanamidocephalosporins 3a-3p were synthesized and tested in vitro antibacterial activity. Of these new cephalosporins exhibited good antibacterial activity against Gram-positive bacteria whereas none of the compounds possessed the activity against Gram-negative bacteria at the concentration tested.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.189-192
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• 1987

The syntheses of mercaptotetrazoles and cephalothin analogs are described. Their in vitro potency was established. The compounds exhibited high antibacterial activity against Gram-positive bacteria and moderate activity against Gram-negative bacteria.

• Korean Journal of Microbiology
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• v.34 no.1_2
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• pp.31-36
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• 1998

A broad spectrum of antibiotic action was studied with Centipedin purified from centipede Scolopendra subspinipes multilans L. Koch aganist gram-positive, gram-negative bacteria and fungi. The minimal inhibitory concentrations(MICs) were determined in liquid medium. The significant antibiotic activity was obtained aganist gram-negative Klebsiella pneumoniae ATCC 8308 responsible for causing infection at lung and intestine. The MIC value against Klebsiella pneumoniae ATCC 8308 was $2{\mu}g/ml$, and this Centipedin was active against Proteus vulgaris NRRL B-123. In addition, it has been shown that Centipedin blocks procaryotic RNA transcription and a little of DNA replication system in vitro. Centipedin did not exhibit any significant cytotoxicity against animal cells such as human blood leukemia (HL-60) and mouse B lymphocyte myeloma cell.

• Journal of Food Hygiene and Safety
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• v.10 no.2
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• pp.65-71
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• 1995

Bacteriocins from lactic acid bacteria have attracted much attention in recent years because of their useful worth in increasing safety and extending shelf life of foods. These substances show an inhibitory effect against some food spoilage bacteria and food-borne pathogens. The inhibitory effect fo the bacteriocin produces by lactic acid bacteria against Listeria monocytogenes(L. monocytogenes) was examined in this study. The culture supernatants of 5 kinds of bacteria among the 10 kinds of testes lactic acid bacteria had the inhibitory activity against Listeria sp., various Gram positive and Gram negative bacteria. Bacteriocin produced by Lactobacillus plantarum(Lact. plantarum) LMG 7945 was the most active toward L. monocytogenes. Bacteriocin production of the Lact. plantarum LMG 7945 cultured on MRS broth was increased late logarithmic phase over early stationary phase. This bacteriocin was stable at heat treatment and acidic pH relatively; The activity was retained after heating at 121$^{\circ}C$ for 15min and was active in the pH range of 2~4 but was lost above pH 5.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.81-85
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• 2003

Direct analysis of microbes such as either gram-positive or gram-negative bacteria without cell lysis was investigated using capillary electrophoresis. Bacteria cells were directly introduced into the microbore fusedsilica capillary, then separated under high electric field in less than 15 min. It was found that a proper dispersion of bacteria cells was important for reproducible results. Migration behavior of bacteria at different storage condition was investigated and many unexpected peaks were observed from bacteria stored at room temperature due to the distortion of cells. This phenomenon was attributed to the change of size and shape of the same bacterium and confirmed by the scanning electron microscopic images.

• International Journal of Industrial Entomology and Biomaterials
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• v.24 no.1
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• pp.37-40
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• 2012

The apidaecins are highly active against Gram-negative bacteria. Here, we show the expression and antibacterial activity of the bumblebee, Bombus ignitus, apidaecin. We PCR-amplified 51 bp of the active domain sequence of the B. ignitus apidaecin gene and expressed the recombinant B. ignitus apidaecin active domain in baculovirus-infected insect cells. The recombinant B. ignitus apidaecin active domain shows bactericidal activity against Gram-negative bacteria, including Pseudomonas tolaasii, a serious pathogen in cultivated mushrooms, but not Gram-positive bacteria. This result suggests that the active domain of the B. ignitus apidaecin is a potential antibacterial agent for the control of bacterial brown blotch diseases.