• Journal of Microbiology and Biotechnology
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• 제19권4호
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• pp.391-396
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• 2009

The chemical compositions, and antibacterial and antifungal effects of essential oils extracted from three coniferous species, Pinus densiflora, Cryptomeria japonica, and Chamaecyparis obtusa, were investigated. Gas chromatography mass analysis of the essential oils revealed that the major components and the percentage of each essential oil were 16.66% $\beta$-phellandrene and 14.85% $\alpha$-pinene in P. densiflora; 31.45% kaur-16-ene and 11.06% sabinene in C. japonica; and 18.75% bicyclo [2,2,1] heptan-2-ol and 17.41% 2-carene in Ch. obtusa. The antimicrobial assay by agar disc diffusion method showed that $2.2{\mu}g$ of Ch. obtusa oil inhibited most effectively the growth of Escherichia coli ATCC 33312 and Klebsiella oxytoca ATCC 10031, whereas the C. japonica oil gave weak antimicrobial activity. The minimal inhibitory concentration(MIC) values for bacterial strains were in the range of 5.45-21.8 mg/ml depending on essential oils, but most Gram-negative bacteria were resistant even at 21.8 mg oil/ml. P. densiflora oil showed the most effective antifungal activity and the MIC values for Cryptococcus neoformans B42419 and Candida glabrata YFCC 062CCM 11658 were as low as 0.545 and 2.18 mg/ml, respectively. Cryp. neoformans B42419 was the most sensitive to all essential oils in the range of 0.545-2.18 mg/ml. Our data clearly showed that the essential oils from the three conifers had effective antimicrobial activity, especially against fungi.

• 한국약용작물학회지
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• 제24권4호
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• pp.303-308
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• 2016

Background: This study aimed to investigate the antioxidat and antimicrobial activities of the methanol extract and its fractions prepared from the roots of Sanguisorba officinalis L. Methods and Results: The antioxidant activities were compared by evaluating the DPPH radical and nitric oxide (NO) scavenging ability. Measurement of DPPH radical scavenging ability showed that the $SC_{50}$ values of the ethyl acetate fraction was $3.85{\mu}g/m{\ell}$. The ethyl acetate fraction exhibited the most effective DPPH radical scavenging ability compared with the other samples. As for the NO scavenging ability, at all tested concentrations, the ethyl acetate fraction showed a higher scavenging activity than that of the extract and other fractions. These results are related to the total phenolic compound and flavonoid contents of the ethyl acetate fraction. Antimicrobial activity against foodborne pathogens was investigated using the disc diffusion assay. The ethyl acetate fraction showed the highest antimicrobial activity against gram-positive Staphylococcus aureus and Bacillus cereus. However, the chloroform fraction had a higher antimicrobial activity against gram-negative Vibrio vulnificus than that of the extract and other fractions. Conclusions: The results show that the ethyl acetate fraction had a higher antioxidant as well as antimicrobial activity, than did the other samples. Therefore, the ethyl acetate fraction has potential application in the food industry.

• Natural Product Sciences
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• 제23권2호
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• pp.125-131
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• 2017

Clitoria ternatea or Commonly known blue pea, is a perennial climber crop native to Asian countries. The current study was aimed to evaluate the antimicrobial activity C. ternatea extract on food borne microorganisms and its antifungal effect on Penicillium expansum. The extract showed significant antimicrobial activity against 3 Gram positive bacteria, 2 Gram negative bacteria and 1 filamentous fungus on disc diffusion assay. The extract also showed good biocidal effect on all Gram positive bacteria tested and P. expansum. However, the kill curve analysis revealed that the fungicidal activity of the extract against P. expansum conidia was depend on the concentration of the extract and the time of exposure of the conidia to the extract. The scanning electron micrograph of the extract treated P. expansum culture showed alterations in the morphology of fungal hyphae. The germination of P. expansum conidia was completely inhibited and conidial development was totally suppressed by the extract, suggesting the possible mode of action of anthocyanin. Besides, the extract also exhibited 5.0-log suppression of microbial growth relative to control in the rice model. The results indicate the potential use of the C. ternatea anthocyanin as food biopreservative.

• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1814-1822
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• 2018

Most people use cosmetics to protect their skin. Preservatives are often used to prevent their contamination upon use. There has been a great demand for natural preservatives due to recent reports on the side effects of parabens. Therefore, we evaluated the antimicrobial activities of Lonicera japonica and Magnolia obovata extracts and determined their potential as natural preservatives. We found that the 50% ethanol extract from L. japonica had antibacterial activity only against S. aureus and P. aeruginosa, while the ethyl acetate fraction showed antimicrobial activity against all six microbial strains tested. On the other hand, the 70% ethanol extract and the ethyl acetate fraction from M. obovata showed antimicrobial activity against all six strains. A synergistic effect against S. aureus, B. subtilis, and C. albicans was confirmed when two ethyl acetate fractions having antimicrobial activity against all six strains were used in combination. Synergistic activity against B. subtilis was also confirmed through kill-time analysis. High-performance liquid chromatography was performed to identify the components of each extract. Based on the minimum inhibitory concentration and the results of a disc diffusion assay, we confirmed that caffeic acid and luteolin influenced the antimicrobial activity of L. japonica and that the antimicrobial activity of M. obovata was influenced by the interaction of magnolol and honokiol with other components. Therefore, this study suggests that the combination of L. japonica and M. obovata extracts may be used as a plant-derived natural preservative.

• 미생물학회지
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• 제53권3호
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• pp.193-199
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• 2017

This study was aimed to evaluate the antimicrobial activity of Penicillium purpurogenum ED76 on several clinically important microorganisms. The endophytic fungus P. purpurogenum ED76 was previously isolated from Swietenia macrophylla leaf. The antimicrobial efficacy of P. purpurogenum ED76 dichloromethane extract was determined via disc diffusion and broth microdilution assay. A kill curve study was conducted and the morphology of extract treated bacterial cells were viewed under scanning electron microscope. The dichloromethane extract showed significant inhibitory activity on 4 test bacteria and 2 test yeasts. The minimal inhibitory concentration of the extract ranged from 125 to $1,000{\mu}g/ml$, which indicates the different susceptibility levels of the test microorganisms to the fungal extract. The kill curve study has revealed a concentration-dependent inhibition for all test microorganisms. With the increase of the extract concentration, the microbial growth was significantly reduced. The scanning electron micrograph of dichloromethane extract-treated Staphylococcus aureus cells showed the total damage of the cells. The cell wall invagination of the bacterial cells also indicates the loss of cellular materials and metabolic activity. The gas chromatography mass spectrometry analysis of the extract also showed that the major compound was stigmasterol, which constitutes 45.30% of the total area. The dichloromethane extract of P. purpurogenum ED76 exhibited significant inhibitory activity on several clinically important bacteria and yeasts. The study proposed a possible mode of action that the extract cause significant damage to the morphology of S. aureus cells.

• 한국임상수의학회지
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• 제34권4호
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• pp.261-267
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• 2017

The aim of this study was to investigate the antibacterial properties of chitosan silver nanocomposites (CAgNCs) using pathogenic Vibrio ichthyoenteri as a bacterial model. Results of agar disc diffusion and turbidimetric assays showed that CAgNCs could inhibit the growth of V. ichthyoenteri in concentration dependent manner. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CAgNCs were 75 and $125{\mu}g/mL$, respectively. Furthermore, CAgNCs treatment induced the reactive oxygen species (ROS) level in V. ichthyoenteri cells in concentration and time dependent manner, suggesting that it generates oxidative stress, leading to bacterial cell death. The field emission scanning electron microscope (FE-SEM) images of CAgNCs treated V. ichthyoenteri exhibited strong cell membrane damage than un-treated control bacteria. MTT assay results showed the highest cell viability (22%) at $75{\mu}g/mL$ of CAgNCs treated bacteria samples. The results from this study suggest that CAgNCs is a potential antibacterial agent to control fish pathogenic bacteria.

• 한국치위생학회지
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• 제17권3호
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• pp.493-504
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• 2017

Objectives: This study aimed to find out the antimicrobial activities of Ramaria botrytis (Fr.) extracts against oral pathogens. Methods: The antimicrobial activities of Ramaria botrytis (Fr.) extracts were evaluated against oral pathogens by the disc diffusion assay, and the minimum inhibitory concentrations (MICs) of ethyl acetate extracts were determined by broth dilution method. The strains used in this study were Staphylococcus aureus, Streptococcus mutans, Streptococcus sanguinis, Streptococcus sobrinus, Streptococcus anginosus, Streptococcus ratti, Streptococcus criceti, Actinomyces israelii, Actinomyces viscosus and Aggregatibacter actinomycetemcomitans. Results: The ethyl acetate extract of Ramaria botrytis (Fr.) effectively inhibited the growth of oral bacteria compared with acetone or ethanol extract. The ethyl acetate extract exhibited MIC values ranging from 3.75 to 15.00 mg/ml, and it showed antimicrobial activity against both Gram-positive and negative oral bacteria. Conclusions: The ethyl acetate extracts from Ramaria botrytis (Fr.) showed the antimicrobial activities against ten oral bacteria. Thus, the extract of Ramaria botrytis (Fr.) may be considered as an effective natural antimicrobial agent for the prevention of oral pathogens.

• 한방재활의학과학회지
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• 제30권1호
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• pp.31-45
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• 2020

Objectives In this study, we investigated the antimicrobial activity of a 70% ethanol extract of Maneung-hwan (MEH), which is prescribed by practitioners of oriental medicine for use against methicillin-resistant Staphylococcus aureus (MRSA). Methods The antibacterial activity of MEH against MRSA strains was evaluated using the disc diffusion method, broth microdilution method (minimal inhibitory concentration, MIC), checkerboard dilution test, and time-kill test. The mechanism of action of MEH was investigated by bacteriolysis using detergents or ATPase inhibitors Additionally, mRNA and protein expression were investigated by quantitative reverse transcription-polymerase chain reaction and western blot assay, respectively. Results The MIC of MEH was 25~1,600 ㎍/mL against all the tested bacterial strains. We showed that MEH extract exerts strong antibacterial activity. In the checkerboard dilution test, the fractional inhibitory concentration index of MEH in combination with antibiotics indicated synergism or partial synergism against S. aureus. The time-kill study indicated that the growth of the tested bacteria was considerably inhibited after a 24-h treatment with MEH and selected antibiotics. To measure the cell membrane permeability, MEH (3.9 ㎍/mL) was combined with Triton X-100 (TX) at various concentrations N,N-dicyclohexylcarbodimide (DCCD) was also tested as an ATPase inhibitor. TX and DCCD cooperation against S. aureus exhibited synergistic action. Accordingly, the antimicrobial activity of MEH in the context of cell membrane rupture and ATPase inhibition was assessed. Additionally, the expression of genes and proteins associated with resistance was reduced after exposing MRSA to MEH. Conclusions These results suggest that MEH possesses antibacterial activity and acts as a potential natural antibiotic against MRSA.

• 미생물학회지
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• 제9권2호
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• pp.86-93
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• 1971

위생환경이 좋지 못하고 보건사업의 혜택이 원활치 못한 지역의 소아 및 국민학동에게서 분리한 장내 세균 중 이열성 장내 독소생성 대장균주의 분포를 배양된 부신암 세포를 이용하여 살펴보았다. 이 열성 장내독소의 존재아래 부신암 세포는 세포의 원형화 및 seroid 생성력의 항진을 보이기에 이 두 성질에 기처를 두어 독소생선균주를 감별하였다. 실험의 결과 조사대상자의 약 10%에 해당하는 균주들이 독소 생성 균주로 밝혀졌다. 분리한 균주의 화학요법제에 대한 감수성 내지 내성도를 측정하였는데 특히 주목할 것은 이열성 장내독소 균주들의 대부분이 gentamycin(10mg)과 nalidixic acid(5mg)에 감수성이 있는데 비해, colistin(10mg), novobiocin(30mg), sulfa drug(50mg)에는 내성을 나타냈으며, 장내 질환에 널리 쓰이는 chloramp-henicol(10mg)에 대해서는 균에 따라 감수성 또는 내성을 보인데 있다. 이상의 조사로 우리나라 정상아동이 상당의 이열성 장내독소 생성균주를 보유하고 있음을 알수 있다. 이를 균주중 몇개는 장내질환 치료제로 널리 사용하는 항생제에 대해 내성을 지니고 있음을 볼 수 있었다.

• 한국미생물·생명공학회지
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• 제48권2호
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• pp.230-235
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• 2020

The global evolution of antibiotic resistance has threatened the efficacy of available treatment options with ravaging impacts observed in developing countries. As a result, investigations into the prevalence of antibiotic resistance and the role of plasmids are crucial. In this study, we investigated the presence and distribution of bla_TEM and gyrA genes, plasmid profiles, and the antimicrobial susceptibility pattern of Salmonella strains isolated from raw meat and stool sources across Niger State, Nigeria. Ninety-eight samples, comprising 72 raw meat and 26 stool samples, were screened for Salmonella spp. The antimicrobial susceptibility of Salmonella isolates to 10 commonly used antimicrobial agents was determined using the KirbyBauer disc diffusion method. Isolates were further analyzed for plasmids, in addition to PCR amplification of beta-lactamase (bla_TEM) and gyrA genes. A total of 31 Salmonella spp. were isolated, with 22 from raw meat (70.97%) and 9 from stool (29.03%). Salmonella spp. with multiple resistance patterns to ceftazidime, cefuroxime, ceftriaxone, erythromycin, ampicillin, cloxacillin, and gentamicin were detected. Ofloxacin and ciprofloxacin were found to be the most effective among the antibiotics tested, with 67.7% and 93.5% susceptible isolates, respectively. Nine (29.03%) isolates harbored plasmids with molecular sizes ranging between 6557 bp and 23137 bp. PCR amplification of gyrA was detected in 1 (3.23%) of the 31 isolates while 28 isolates (90.32%) were positive for bla_TEM. This study shows the incidence of antibiotic resistance in Salmonella isolates and the possible role of plasmids; it also highlights the prevalence of ampicillin resistance in this local population.