• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.637-643
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• 1991

The inhibitory activity of Lactobacillus plantarum Lp2 isolated from Kimchi was investigated against E. colz, Staphylococcus aureus, Str. faecalis, P. aeruginosa and psycrotrophic strain Pcl. The addition of ether extract from Lp2 culture broth completely inhibited the growth of E, coli, P. aeruginosa and Pc1, but the inhibitory action was weak against S. aureus and Str. faecalis. The inhibitory substance(s), soluble in methanol, acetone and ethyl ether, was active in the pH range of 5 and 6, but the activity was lost above pH 6. The activity was retained after heating at $121^{\circ}C$ for 15 min. By dialysis, the molecular weight of the inhibitory substancek) was estimated under 1000. The TLC analysis of Lp2 ether extract revealed the presence of three bands and the inhibitory activity was found in that of $R_f$ value 0.73.

• International Journal of Oral Biology
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• v.41 no.4
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• pp.209-215
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• 2016

Chlorhexidine has long been used in mouth washes for the control of dental caries, gingivitis and dental plaque. Minimal inhibitory concentration (MIC) is the lowest concentration of an antimicrobial substance to inhibit the growth of bacteria. Concentrations lower than the MIC are called sub minimal inhibitory concentrations (sub-MICs). Many studies have reported that sub-MICs of antimicrobial substances can affect the virulence of bacteria. The aim of this study was to investigate the effect of sub-MIC chlorhexidine on biofilm formation and coaggregation of oral early colonizers, such as Streptococcus gordonii, Actinomyces naeslundii and Actinomyces odontolyticus. The biofilm formation of S. gordonii, A. naeslundii and A. odontolyticus was not affected by sub-MIC chlorhexidine. However, the biofilm formation of S. mutans increased after incubation with sub-MIC chlorhexidine. In addition, cell surface hydrophobicity of S. mutans treated with sub-MIC of chlorhexidine, decreased when compared with the group not treated with chlorhexidine. However, significant differences were seen with other bacteria. Coaggregation of A. naeslundii with A. odontolyticus reduced by sub-MIC chlorhexidine, whereas the coaggreagation of A. naeslundii with S. gordonii remained unaffected. These results indicate that sub-MIC chlorhexidine could influence the binding properties, such as biofilm formation, hydrophobicity and coaggregation, in early colonizing streptococci and actinomycetes.

• Journal of dental hygiene science
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• v.20 no.4
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• pp.221-229
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• 2020

Background: The purpose of this study was to investigate the anti-oral microbial activity and anti-inflammatory effects of rosmarinic acid (RA) in lipopolysaccharide (LPS)-stimulated MC3T3-E1 osteoblastic cells on a titanium (Ti) surface during osseointegration, and to confirm the possibility of using RA as a safe natural substance for the control of peri-implantitis (PI) in Ti-based dental implants. Methods: A disk diffusion test was conducted to confirm the antimicrobial activity of RA against oral microorganisms. In order to confirm the anti-inflammatory effects of RA, inflammatory conditions were induced with 100 ng/ml of LPS in MC3T3-E1 osteoblastic cells on the Ti surface treated with or without 14 ㎍/ml of RA. The production of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS-stimulated MC3T3-E1 osteoblastic cells on the Ti surface was confirmed using an NO assay kit and PGE2 enzyme-linked immunosorbent assay kit. Reverse transcription polymerase chain reaction and western blot analysis were performed to confirm the expression of interleukin (IL)-1β and tumor necrosis factor (TNF)-α in total RNA and protein. Results: RA showed weak antimicrobial effects against Streptococcus mutans and Escherichia coli, but no antimicrobial activity against the bacteria Aggregatibacter actinomycetemcomitans and the fungus Candida albicans. RA reduced the production of pro-inflammatory mediators, NO and PGE2, and proinflammatory cytokines, TNF-α and IL-1β, in LPS-stimulated MC3T3-E1 osteoblastic cells on the Ti surface at the protein and mRNA levels. Conclusion: RA not only has anti-oral microbial activity, but also anti-inflammatory effects in LPS-stimulated MC3T3-E1 osteoblasts on the Ti surface, therefore, it can be used as a safe functional substance derived from plants for the prevention and control of PI for successful Ti-based implants.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.4
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• pp.577-583
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• 2014

In this study, we evaluated fermentation characteristics of microorganism with antimicrobial activity in makgeolli made from various kinds of koji and nuruk during fermentation. The pH of nuruk groups decreased compared to the koji groups after 3 days of fermentation. Acidity and alcohol contents of nuruk groups significantly increased compared to the koji groups. The total sugar contents of the koji groups were significantly higher than those of the nuruk groups after 15 days of fermentation. Sensory scores of koji groups (DKB) were higher than those of other samples. Antimicrobial activities of nuruk group (GND and ANF) against Salmonella enterica, Bacillus subtilis, Escherichia coli, and Bacillus cereus were significantly higher compared to the koji group. ST-1, isolated from (Geumjeonggu nuruk D), showed the highest antimicrobial activity and was identified as Paenibacillus polymyxa strain RCP6 based on 16S rRNA sequencing. Our result suggest that Paenibacillus polymyxa from nuruk group produces a bacteriocin-like substrate with antimicrobial activity.

• Journal of Food Hygiene and Safety
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• v.22 no.4
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• pp.317-322
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• 2007

The purpose of this study was to investigate the antibacterial effect of films on shelf-life and microbiological safety of mackerel. Effects of antimicrobial films against total aerobic bacteria, Escherichia coli O157:H7, Listeria monocytogenes, Vibrio parahaemolyticus in mackerel were evaluated during storage of 5-14 days at $5^{\circ}C,\;10^{\circ}C\;and\;15^{\circ}C$. Antimicrobial films were developed with addition of a natural substance, wasabi extracts (Wasabia japonica). At $5^{\circ}C$ storage, growth of total aerobic bacteria, Escherichia coli O157:H7, Listeria monocytogenes were inhibited higher than at 10 and $15^{\circ}C$. Especially, the numbers of V. parahaemolyticus were decreased gradually at $5^{\circ}C$ even in the control sample, and about $1\;log_{10}cfu/g\;and\;1.8\;log_{10}cfu/g$ reductions were observed at 1 and 4 days, respectively. After 7 days, V. parahaemolyticus in all samples were not detected. There is a limit of a single treatment of antimicrobial film to prolong shelf-life of mackerel. The synergistic effect of antimicrobial film were shown by addition of $5^{\circ}C$ refrigeration.

• Food Science and Preservation
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• v.18 no.2
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• pp.219-225
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• 2011

We investigated the antimicrobial and antioxidant activities. and total polyphenol contents of Curcuma longa. Curcuma aromatica. and Curcuma zedoaria. In antimicrobial activity assays of solvent extracts, ethanol extract showed the highest activity compared with other extracts. The antimicrobial activity of ethanol extract of C. longa showed higher than those of C. aromatica, and C. zedoaria. Antimicrobial substance in ethanol extract of C. longa was maintained after heating at $100^{\circ}C$ for 30 min and not affected by changes in pH. DPPH free radical scavenging activity of solvent extracts were high in the order of ethanol, ethylacetate, ether, water, and hexane fractions, C. longa showed greater DPPH free radical scavenging activity than those of the C. aromatica, and C. zedoaria. Total polyphenol content of C. longa and C. aromatica exhibited were similar levels, whereas C. zedoaria was slightly lower concentration.

• Microbiology and Biotechnology Letters
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• v.38 no.1
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• pp.32-39
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• 2010

This study was carried out to investigate the usefulness of the natural antimicrobial substances for natural dyeing. Antimicrobial activity of natural substances, extracted by water, ethanol, methanol and ethyl acetate, were shown over 20 mm by Rheum palmatum, Caesalpinia sappan, Prunus mume, Schizandra chinensis, Rhus javanica, and Coptis japonica. Especially, water and methanol extract of C. japonica were shown strong antimicrobial activity against all investigated strains. Minimum inhibition concentration of C. japonica water extract was investigated 110 mg/mL for Staphylococcus aureus ATCC 6538. Investigated natural substances were not only shown strong antimicrobial activity for natural dyeing but also might be used other industries.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.354-361
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• 2018

This study was carried out to isolate soil bacteria with antimicrobial activity and evaluate antimicrobial substances produced by isolated bacteria. Among many isolates Bacillus subtilis DS660 and Paenibacillus polymyxa DS842 showed high antimicrobial activities against 6 species of microbial residents on human skin and 3 species of pathogenic bacteria. DS660 and DS842 showed 15.3~26.8 and 11.3~27.5 mm of inhibition zone diameter, respectively on nutrient agar medium against most target bacteria and fungi. DS660 and DS842 produced $57{\pm}8$ and $170{\pm}15{\mu}mol/ml$ of siderophore, respectively as an antimicrobial substance. Analysis of ethyl acetate extract of culture supernatants of DS660 and DS842 suggested production of glycolipid biosurfactant which reduced surface tension of culture supernatant of DS660 and DS842 from 60.0 to 40.3 and 30.3 mN/m, respectively. DS660 and DS842 also showed $169.2{\pm}9.9$ and $357.2{\pm}13.7nmol/min/mg$ protein of ${\beta}-1,3$-glucanase activity, respectively, and hydrolyzed cell wall components of 3 bacterial species. These results suggest that B. subtilis DS660 and P. polymyxa DS842 may be utilized as an environment-friendly biocontrol agent against some skin microbes and pathogenic bacteria.

• Journal of Life Science
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• v.34 no.7
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• pp.493-499
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• 2024

Antimicrobial peptides are antimicrobial substances inherent in animals and plants, with strong antibacterial activity even in small amounts and with various other functions such as antiviral and antioxidant actions. Plants can be grown with just water and sunlight, allowing for their mass production at low costs. However, transforming a chloroplast into one that produces antimicrobial peptides, rather than growing plants, increases the amount of protein expression and minimizes contamination of the ecosystem because gene transfer by pollen does not occur. In that context, using transgenic plant chloroplasts to produce recombinant proteins increases protein degradation and reduces the solubility of proteins. To solve this problem, we fused SUMO, a fusion protein, with a recombinant protein. We also used a 6xHis tag to purify the fusion protein. The antimicrobial peptide stomoxyn is an antibacterial substance found in stable flies. Stomoxyn has an α-helix structure and is amphiphilic, which allows it to dissolve bacterial cell membranes. In this study, we constructed a transformation vector to express stomoxyn in both plant chloroplasts and Escherichia coli and used this vector to confirm the expression of stomoxyn in E. coli. The expression of the protein was then confirmed in E. coli using a transformation vector. The expressed stomoxyn was purified by nickel column and SUMOase treatment, and its antibacterial activity was confirmed using an agar diffusion assay. The EGFP gene was used to ensure that the transformed vector was inserted into the chloroplast.

• Microbiology and Biotechnology Letters
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• v.10 no.3
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• pp.211-215
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• 1982

Streptomyces griseorubiginosus var. soyoensis previously identified, produced two kinds of antifungal antibiotics, trans-cinnamamide and another new substance. The latter was identified to be a new substance of tetraene family by establishment of UV, IR, NMR, mass spectra and chemical reactions and rotatively named as Tetraene KM-A. Through an antimicrobial activity test using serial agar dilution method, Tetraene KM-A showed strong growth inhibitory activity against fungi and yeasts, but not against procaryotes tested. The inhibitory action of Tetraene KM-A on fungi was remarkably ineffective when some of sterols were added to the cultural media. $LD_{50}$ of the Tetrene KM-A to mice and rats by intravenous injection were 84.3 and 90.4 mg/kg respectively. $LD_{50}$ to mice by oral feeding was 1503mg/kg.