• Korean Journal of Veterinary Research
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• v.33 no.3
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• pp.419-427
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• 1993

Thirteen strains of Clostridium perfringens were isolated from the pigs with hemorrhagic enteritis. The characteristics of the outbreaks, clinical signs and lesions were examined. The biochemical properties, type of toxin and susceptibility to antimicrobial agents of the isolates were investigated. The results could be summarized as follows ; 1. Almost of the pigs affected with hemorrhagic enteritis, 17 cases examined from 1989 to 1992, were piglets less than 7 day old. 2. The average mortality rate of piglet less than 7 day old affected with hemorragic and necrotic enteritis was 48.5%. 3. The clinical signs of pigs with hemorrhagic enteritis were depression, hemorrhagic diarrhea, anemia and dehydration. Necropsy of the infected pigs showed typical hemorrhage of upper intestine and necrosis of mucosal membrane. 4. The characteristic biochemical properties of the isolates were 2-band hemolysis, positive reaction of reverse CAMP test and formation of LV precipitate in egg yolk medium. 5. The toxin type of the 13 isolates, investigated by mouse inoculation test, was all type C strains of Clostridium perfringens. 6. In susceptibility test to antimicrobial agents, 13 isolates of Clostridium perfringens were highly sensitive to ampicillin, enrofloxacin(Baytril), cephalothin, penicillin and trimethoprim-sulfamethoxazole.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2577-2583
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• 2011

We have designed a 20-residue hybrid peptide CA(1-8)-MA(1-12) (CAMA) incorporating residues 1-8 of cecropin A (CA) and residues 1-12 of magainin 2 (MA) with high bacterial cell selectivity. CAMA-P2 is an ${\alpha}$-helical antimicrobial peptide designed from a CAMA hybrid peptide and substitution of Gly-Ile-Gly hinge sequence of CAMA to Pro influences the flexibility at central part of CAMA. Based on structure-activity relationships of CAMA peptides, to investigate the effects of the total positive charges on antimicrobial activity of CAMA-P2, the $Ser^{14}{\rightarrow}$Lys analogue (CAMA-syn1) was synthesized. The role of tryptophan at C-terminal ${\alpha}$-helix on its antimicrobial activity as well as synergistic activity was also investigated using $Ser^{14}{\rightarrow}$Lys/$Phe^{18}{\rightarrow}$Trp analogue (CAMA-syn2). Also, we designed CAMA-syn3 by substitution of $Lys^{16}$ located opposite side of substituted $Lys^{14}$ of CAMA-syn1 with Leu residue, resulting in increase of hydrophobicity and amphipathicity of the peptide. All of CAMA-syn analogues showed good antimicrobial activities similar to those of CAMA and CAMA-P2. The CAMA-syn1 and CAMA-syn2 showed low hemolytic activity and cytotoxicity against human keratinocyte Haca-T cells while CAMA-syn3 showed hemolytic activity and cytotoxicity at its MIC value. We then investigated their abilities to act synergistically in combination with the antimicrobial flavonoids and synthetic compounds screened in our laboratory. The results showed that all peptides exhibited synergistic effects with dihydrobinetin, while only CAMA-syn2 exhibited synergistic effects with YKAs3001 against both S. aureus and MRSA, suggesting that Trp residue at C-terminus of CAMA-syn2 may facilitate the polar antibiotic flavonoids and synthetic compounds to permeabilize the membrane. This study will be useful for the development of new antibiotic peptides with potent antimicrobial and synergistic activity but without cytotoxicity.

• Journal of Microbiology and Biotechnology
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• v.32 no.8
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• pp.1003-1010
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• 2022

The purpose of this study was to examine the phytochemical compounds and antibacterial activity of Coffea robusta leaf extract (RLE). The results indicated that chlorogenic acid (CGA) is a major component of RLE. The minimum inhibitory concentrations (MICs) of RLE against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella Typhimurium were 6.25, 12.5, 12.5, and 12.5 mg/ml, respectively. RLE effectively damages the bacterial cell membrane integrity, as indicated by the high amounts of proteins and nucleic acids released from the bacteria, and disrupts bacterial cell membrane potential and permeability, as revealed via fluorescence analysis. Cytotoxicity testing showed that RLE is slightly toxic toward HepG2 cells at high concentration but exhibited no toxicity toward Caco2 cells. The results from the present study suggest that RLE has excellent potential applicability as an antimicrobial in the food industry.

• Journal of Food Hygiene and Safety
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• v.10 no.1
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• pp.33-39
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• 1995

The antibacterial and antifungal effect of grapefruit seed extract(GFSE) was investigated for its purpose of application to a diverse spectrum of field as sanitizers, disinfectants and preservatives. GFSE showed coparatively high content of such flavoniods as naringin and hesperidin and ascorbic acid. GFSE containing a low level of organic acids is a heavy viscous and water-soluble liquid. As a result of the antimicrobial test of GFSE, Bacillus subtilis and Aspergillus oryzae did not survive at detectable levels when treated with more than 100 ppm of GFSE. The minimum inhibitory concentrations of GFSE for a wide variety of pathogenic and putrefactive bacteria, fungi and yeasts were 100 ppm and 250 ppm, respectively. In the comparable electron micrograph of microbial cells treated with GFSE or not, we could conclude that GFSE destroy microorganisms by disrupting the functions of the cell wall membrane and microbial spores.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1086-1093
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• 1998

The antimicrobial effect of mixed solutions of grapefruit seed extract(250ppm) and ascorbic acid(1%) on the spoilage microorganisms such as Staphylococcus epidermis, Escherichia coli, Pseudomonas syringae, Candida albicans and Corynebacterium xerosis isolated from the spoiled soybean sprouts were investigated. Cell wall and membrane were partially destroyed and the contents of the destroyed cell were exuded after treatment. Packages with 30 m cast polypropylene(CPP), 16 m polyolefin(RD 106) and 10 m high density polyethylene(HDPE) were applied for soybean sprouts dipped in mixed solutions respectively. Oxygen and carbon dioxide concentration inside packages were dependent on the kind of films during storage at 5oC. The antimicrobial activity of mixed solutions was maintained for 5 days at CPP package. Package with HDPE showed a severe browning than the others after 5 days. Ascorbic acid content of mixed solution treatment was higher than that of control for each package.

• The Korean Journal of Food And Nutrition
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• v.13 no.2
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• pp.139-145
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• 2000

To separate anticaries and antiinflammation from Aloe vera peel, we investigated a inhibited effect of Streptococcus mutans JC-2 that was antibiosis, glucosyltransferase activity about aloe-emodin and barbaloin. Aloe-emodin and barbaloin had strong antibiosis activity against Streptococcus mutans JC-2, they were especially antibiosis effect to low growth and prolong lag phase at attachment concentration 100$\mu\textrm{g}$/mL. The reduction rate of a culture fluid became to lessen than the comparison group for aloe-emodin and barbaloin. The intracellular materials of Streptococcus mutans JC-2 were to leakage as much as attachment concentration addition of aloe-emodin and barbaloin but there was no significant difference membrane demage between two active substances. The activity of GTase was inhibited by aloe-emodin and barbaloin and their inhibition rate was respectively 99.8%, 98.4% at the attachment concentration 100$\mu\textrm{g}$/mL.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.147-148
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• 2001

Many people living in Asia countries, particularly Korea, Japan and China, have consumed very widely fresh seafood products, such as shrimps, oysters, mussels and other marine invertebrates and fishes, without any heating or cooking. A variety of Vibrio spp., including V. parahaemolyticus, V. cholera. V. vulnificus, and V. fluvialis, lives in these seafoods and cause great problems associated with human disease. A strong antimicrobial agent to effectively inhibit the growth of these pathogenic bacteria in in vivo or in vitro is urgently need for preventing fish and human diseases. (omitted)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.151-152
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• 2001

Chitin, a polymer of N-acetylglucosamine ($\beta$-1,4 linked 2-acetamido-D-glucose), is a cellulose-like biopolymer present richly in the exoskeleton of crustaceans and in cell walls of fungi, insects and yeast. Chitosan is derived from chitin by deacetylation, to different degrees, in the presence of alkali. [l]. Recent studies for chitin and chitosan have been concentrated in bioactivities such as antitumor activity, immuno-enhancing effects, enhancing protective effects against infection with some pathogens in mice, and antimicrobial activeity [2]. (omitted)

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.771-776
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• 2005

In recent days, there is much interest in the biocidal activity of silver since silver is known to be safe and effective as disinfectant and biocidal material against coliforms and viruses. In particular, nano silted silver particles which can be used as effective biocidal material received more attention. Accordingly, it is important to investigate antimicrobial activity and mechanism of nano sized silver particles prepared in a cost-effective manner. In this study, nano sized silver particles were prepared via photoreduction of a silver salt ($AgNO_3$) in the bulk phase of $PEO_{20}-PPO_{70}-PEO_{20}$ (Pluronic 123) block copolymer The antimicrobial efficacy of silver nano particles against E. coli was investigated and compared with that of silver ion as the concentration of silver nano particles, pH ($5.6{\sim}8.2$), temperature ($4^{\circ}C{\sim}35^{\circ}C$) varied in aqueous system. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) was used to examine the nature of damaged microorganism with nano sized silver particles and silver ion. This study showed that antimicrobial efficacy of silver nano particles was approximately one twentieth than that of silver ion. It was more biocidal at higher pH in contrast with silver ion. In addition, nano silver particles was demonstrated to disrupt the outer membrane of E. coli, subsequently causing their aggregation. On the other hand, silver ion diffused into the cell damaging the cytoplasmic membrane without disrupting the outer membrane of E. coli.

• Food Science and Preservation
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• v.11 no.3
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• pp.411-416
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• 2004

Botanical antimicrobial agent-grapefruit seed extract mixture(BAAG), which could be applied to the preparation of antimicrobial packaging paper, was investigated in order to prove the preservative function of fruits and vegetables. HAAG showed remarkable antimicrobial effects against Fusarium solani Botrytis cinerea, Pencillium crustosum, Erwinia carotovora, Phoma destructiva and Alternaria radicina causing the postharvest decay of fruits and vegetables. We have examined that HAAG could inhibit the growth of microorganims when treated with more than 500 $\mu$g/mL concentration. The activities of HAAG were stable in the wide spectrum of pH and temperature. Direct visualization of microbial cells by using scanning electron microscope showed the loss of microbial cell membrane function, which was destroyed by treating with the dilute solutions of HAAG. We could confirm that HAAG be an antimicrobial agent for the preparation of antimicrobial packaging paper.