• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.2
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• pp.328-332
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• 2014

A survey was conducted on the isolation of lactic acid bacteria with antibacterial activity to extend kimchi shelf-life. Antibacterial activity was tested against bacteria associated with acidification of kimchi, including Lactobacillus plantarum, Pediococcus pentosaceus, and Lactobacillus sakei, using agar-well diffusion assay. Two isolates from kimchi were identified as Lactococcus lactis subsp. lactis and Lactobacillus brevis by 16S rRNA gene sequence analysis and API 50 CHL assay, and they showed antibacterial effects against indicator strains. The isolates displayed acid tolerance at pH 3.5, salt tolerance in 5% NaCl, and growth at $4^{\circ}C$. These result imply that the selected strains might be used to extend kimchi shelf-life as a potential starter.

• Journal of Veterinary Clinics
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• v.31 no.3
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• pp.194-198
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• 2014

Methicillin-resistant staphylococci (MRS) are emerging as important pathogens in humans and animals worldwide. The aim of this study was to investigate the prevalence of MRS in the racehorse population and in horse-related personnel in Korea. A total of 195 horses and 18 humans (eight veterinarians, three veterinary hospital staff, and seven horse-handlers) from racehorse farms in Korea were included in the study. The samples were collected from nasal cavities using bacterial transport medium and were cultivated on tryptic soy agar with 5% sheep blood for 3 days at $37^{\circ}C$ to confirm the presence of Staphylococcus spp. Presumptive Staphylococcus spp. isolates were identified by 16S ribosomal RNA gene analysis. The coagulase test and oxacillin susceptibility tests were performed using the tube dilution and disk diffusion methods, respectively. The presence of the mecA gene was determined using a polymerase chain reaction assay. Of the 195 horses, 29 (15.6%) yielded 29 MRS isolates. Twelve (66.7%) of the 18 horse-related personnel yielded 12 MRS isolates. All of the MRS isolates from horses or horse-related personnel were identified as methicillin-resistant coagulase-negative staphylococci (MRCNS). The result of this study suggest that the prevalence of MRS increased with the duration of antibiotic use (p = 0.002). This study also provides evidence for the zoonotic transmission of MRCNS between horses and humans, although further investigations are needed.

• Korean Journal of Plant Resources
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• v.30 no.2
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• pp.133-143
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• 2017

This study was conducted to evaluate the contents of total polyphenol and flavonoid, and the effect of antioxidant, antimicrobial activities and cytotoxicity in vitro by different solvent fractions from Orostachys japonicus. The ethylacetate fraction extract for O. japonicus contained $634.48{\mu}g/g$ polyphenol and $205.20{\mu}g/g$ flavonoid. The ABTS radical scavenging ability of ethylacetate fraction extract at 1 mg/ml was higher than 95% which is comparable to ascorbic acid of 97%. The APX enzymatic activity and CAT activity were $1125.89{\mu}mol$ ascorbate oxidized/min/mg protein and 119.87 H2O2 decomposed/min/mg protein, respectively. In disc agar plate diffusion assay, the extract gave rise to a larger inhibition circle with Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus and Malassezia furfur strains compared with antibiotics kanamycin suggestive of high antibiotic activity. The cytotoxicity of extracts of O. japonicus was significant differences between solvent fractions. That is, the cytotoxic effect against human cancer cell was higher in ethylacetate fraction extract than other fraction extracts. These results suggest that fraction extract of O. japonicus might be very effective and economical in developing natural antioxidant and antimicrobial.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.42-48
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• 2009

Anticandidial activity of seven herbal extracts, Taraxacum Platycarpum, Houttuyniae Herba, Lonicerae Flos, Anemarrhena Rhizome, Forsythia Fruit, Paeoniae Ratix, and Coptidis Rhizoma, were determined against five different Candida sp. by agar diffusion assay. The concentration of total phenolic compounds of seven herbal extracts ranged from 0.6 to $2.5{\mu}g/mg$. The total antioxidant activities showed that Taraxacum Platycarpum and Houttuyniae Herba were 60% in 80% ethanol extract and Lonicera Flower and Paeoniae Ratix were 70, 75%, respectively, in 100% ethanol extract. Coptidis Rhizoma extract showed antifungal activity against non-Candida albicans, C. tropicalis and C. glabrata. The MIC values of a compound separated in TLC from Coptidis Rhizoma extract were 24, and $48{\mu}g/mL$ against C. tropicalis and C. glabrata. The above compound showed the same retention time with berberin in HPLC analysis.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.4
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• pp.355-364
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• 2016

This study was initiated to evaluate the antioxidant and antimicrobial activities of methanol extract (ME) and hot water extract (HWE) obtained from the fruiting bodies of medicinal mushroom, Phellinus gilvus. The free radical scavenging activity of ME from P. gilvus on 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 93.65% at 2 mg/mL, which was comparable with the positive control, butylated hydroxytoluene (BHT, 96.97%) at the same concentration. The ferrous ion-chelating ability of ME and HWE was significantly higher than that of BHT at all concentration levels. The antimicrobial assay of ME was performed against six bacteria and one species of fungus. ME exhibited antibacterial activity against 5 out of 6 bacteria: Staphylococcus aureus, Streptococcus mutans, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa; whereas, ME did not show antimicrobial activity against gram-negative bacterium Vibrio vulnificus and fungal species Candida albicans. The minimum inhibitory concentration (MIC) of ME against 5 strains of bacteria, such as S. aureus, S. mutans, B. subtilis, E. coli, and P. aeruginosa, was 100, 100, 50, 100, 200 mg/mL, respectively. The results suggest that good antioxidant and microbial activities of P. gilvus fruiting bodies might be used for natural antioxidant and antimicrobial agents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.5
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• pp.721-726
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• 2012

Lactic acid bacteria (LAB) are able to secrete antimicrobial peptides called bacteriocins, which inhibit other bacteria such as pathogenic microorganisms. Therefore, bacteriocin-producing starters can be used as natural biopreservatives for various foods. The objective of this study was to screen and characterize bacteriocin-producing LAB from Kimchi and to investigate their applicability as a starter in Kimchi fermentation. To screen bacteriocin-producing LAB, gram-positive and gram-negative bacteria were used as indicators. To measure the antimicrobial activities of isolates, agar well diffusion assay method was used. According to the results, bacteriocin produced by $Lb.$ $sakei$ B16 showed antimicrobial activity against $Listeria$ $monocytogenes$ ATCC 19115, $Escherichia$ $coli$ KCTC 1467, and$Lactobacillus$ $plantarum$ KTCT 3104. Furthermore, bacteriocin was very stable after treatment with high temperature and high and low pH, but its effects were inhibited by treatment with proteolytic enzymes such as trypsin, proteinase K, and ${\alpha}$-chymotrypsin, revealing their bacteriocin-like protein- based structure. These results suggest that $Lb.$ $sakei$ B16 and its bacteriocin are good candidates as a functional probiotic and natural biopreservative, respectively, in fermented foods.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.478-486
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• 1995

Periodontal therapy for treatment of periodontitis involves the elimination of bacterial plaque and elimination of the anatomic defects by regenerative procedure. The purpose of this study was to evaluate on the biological effect of magnolia and Ginkgo biloba extract to the antimicrobial, antiinflammatory and cellular activity. Antimicrobial assay was performed with the diffusion method of the extract by measuring of growth inhibitory zone of B. cereus from blood agar plate. Effect of the extract to cellular activity of gingival fibroblast were examined using MTT method and measured the result with optical density on 570nm by ELISA reader. Inhibitory effects of $PGE_2$ production from gingival fibroblast was performed with the addition of $IL-l{\beta}$ and the extract to the well and examined to the product of $PGE_2$ from cell by ELISA reader. In vivo anti-inflammatory effect was performed with injection examined with clinically and histologically for their extent of mecrosis and inflammation. Antimicrobial activity of Magnolia extract showed significantly higher activity than that of control. However, GBE did not showed significant activity to compare with control, and mixture of Magnolia and GBE extract showed significantly higher activity than that of control. The effect of cellular activity to gingival fibroblast showed no significant differences of between control and Magnolia extract. However, GBE showed significantly higher rate of cellular activity to compare with control and even to PDGF-BB, and also showed same degree of cellular activity even though mixed with Magnolia extract. The inhibitory effect of $PGE_2$ production showed significantly reduction of $PGE_2$ production to compare with control, but its inhibitory effect was not much strong to compare with Indomethacin. In vivo, antiinflammatory effect of Magnolia extract to P. gingivalis injection of Hamster buccal check showed significantly reduction of inflammatory cell infiltration and tissue necrosis, but GBE showed no effect on the inhibition of inflammatory process. These results suggested that Magnolia and GBE extract possessed different kind of biological activity and also can be compensated on their activity with each other for elimination of bacterial plaque and anatonical defect.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.495-500
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• 2013

This study was performed to identify safe natural food preservatives from medicinal herbs and to evaluate the antimicrobial effects of medicinal plants against microorganisms. Medicinal herbs were extracted 3 times with methanol at $45^{\circ}C$ for 3 h and fractionated with n-hexane. The antimicrobial effects of the fractions were determined by measuring the diameter of the inhibition zone by using an agar-well diffusion assay. The MIC of fractions for the inhibition of microorganisms was determined using a microplate reader. The antimicrobial effects of fractions were greater against gram positive bacteria than against gram negative bacteria, but the difference was not significant. The antimicrobial effects of fractions were concentration dependent. While these results have implications, the underlying mechanisms of microbial inactivation need to be further elucidated. The results showed the possibility of developing safer food preservatives.

• KSBB Journal
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• v.21 no.1 s.96
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• pp.42-48
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• 2006

Bacillus subtilis KMU-13 was isolated from the Lillehammer forest soils at Norway and shown a strong antifungal activity on cucumber scab, Cladosporium cucumerinum KACC 40576. B. subtilis KMU-13 produced a maximum level of antifungal substance under incubation aerobically at $30^{\circ}C$, 180 rpm for 48 hours in LB broth containing 0.5% maltose and 0.5% bactopeptone and initial pH adjusted to 6.0. Butanol extract of cultured broth was confirmed inhibitory zone by plate assay and Rf 0.64 value substance by thin layer chromatography (TLC) represented high antifungal activity against C. cucumerinum KACC 40576 and also shown fungal growth inhibitory activity against Botytis cinerea KACC 40573, C. gloeosporioides KACC 40804, D. byoniae KACC 40669, F. oxysporum KACC 40037, F. oxysporum KACC 40052, F. oxysporum f. sp. radicis-lycopersici KACC 40537, F. oxysporum KACC 40902, M. cannonballus KACC 40940, P. cambivora KACC 40160, R. soiani AG-1 KACC 40101, R. solani AG-4 KACC 40142, and S. scleotiorum KACC by agar diffusion method.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.564-570
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• 2003

The antibacterial mechanism of enterobacter Salmonella typhimurium was studied. The rfa (Waa) gene cluster of S. typhimurium encodes the core oligosaccharide biosynthesis of lipopolysaccharide (LPS). Among the rfa gene cluster, we recently cloned the rfaE gene, which is involved in ADP-L-glycero-D-manno-heptose biosynthesis. The rfaE mutant synthesizes heptose-deficient LPS, which consists of only lipid A and 3-deoxy-D-manno-octulosonic acid (KDO), thus making an incomplete LPS and a rough phenotype mutant. S. typhimurium deep-rough mutants with the heptose region of the inner core show a reduced growth rate, sensitivity to high temperature, and hypersensitivity to hydrophobic antibiotics such as baicalin isolated from the medicinal herb of Scutellaria baicalensis Georgi. Thus, in this study, the cloned rfaE gene was added to the S. typhimurium rfaE mutant strain SL1102 (rfaE543), which makes heptose-deficient LPS and has a deep-rough phenotype. The complementation created a smooth phenotype in the SL1102 strain. The sensitivity of SL1102 to bacteriophages was also recovered to that of wild-type strain, indicating that LPS is used as the receptor for bacteriophage infection. The permeability barrier of SL1102 to hydrophobic antibiotics such as novobiocin and baicalin was restored to that of the wild-type, suggesting that antibiotic resistance of the wild-type strain is highly correlated with their LPS. Through an agar diffusion assay, the growth-inhibition activity of baicalin was fully observed in the mutant SL1102 strain. However, only a half of the inhibitory activity was detected in the rfaE complemented SL1102 strain. Furthermore, the LPS produced by the rfaE-complemented SL1102 strain was indistinguishable from LPS biosynthesis of smooth strains.