• Korean Journal of Microbiology
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• v.48 no.4
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• pp.270-274
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• 2012

Three actinobacterial strains exhibiting broad spectrum antibiotic activities were isolated from soil, and characterized. Through the comparative analysis of 16S rRNA genes, the three isolates could be assigned to the genus Streptomyces, as S. tanashiensis, S. nashivillensis, and S. rubiginosohelvolus were found to be the mostly related species, but the strains formed independent phylogenetic lineage. Each strain exhibited different antimicrobial profile against Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus, Gram-negative bacteria Salmonella typhi, Enterobacter cloacae, Serratia marcescens, and Pseudomonas aeruginosa, and also fungi Candida tropicalis and Candida krusei. In addition to the antimicrobial profile, the strains also differed in API ZYM test results, which implies that the three strains might produce difference antimicrobial substances.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.73-80
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• 2023

Broad range of fatty acids were reported to show antimicrobial activities against broad range of microorganisms. However, possible changes of the antibacterial activity of a fatty acid based on structural variations are largely unknown. This study was focused on determination and comparison of the antimicrobial activities of the medium chain fatty acids, based on the position of carboxyl groups on either terminal end, against the representative food-pathogenic bacteria. Over all, mono-carboxyl medium chain fatty acids (MC-MCFA) presented stronger antimicrobial activities against the food-pathogenic bacteria tested including methicillin-resistant Staphylococcus aureus (MRSA) than di-carboxyl medium chain fatty acid (DC-MCFA). In addition, some of MC-MCFA and DC-MCFA showed high possibility to be used as a synergistic adjuvant for both the commercial β-lactam family antibiotics and aminoglycoside family antibiotics against MRSA.

• Proceedings of the SCSK Conference
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• 1992.09a
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• pp.46-68
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• 1992

To investigate the effect on the antimicrobial activity against S.aureus ATCC 6538, E.coli KCTC 1039 and cell toxic level against transformed mouse fibroblast L929 in formula added with various concentrations of UVB blockers commonly used in cosmetic products, these experiments were carried out by preservative efficacy testing methods and in vitro cytotoxicity methods. The results obtained were as follow ; 1) Octyl Dimethyl PABA had a broad antibacterial spectrum against the Gram (+) and the Gram(-) bacteria at 5.84 % concentration, but not Octyl Methoxycinnamate. 2) Antibacterial activity was decreased in a combined UVB blocker system of squalane base. Especially, Octyl Dimethyl PABA was inactivated by Octyl Methoxycinnamate at 5.84% concentration to a large extents , but not 4-Methylbenzylidene Camphor. 3) Within in vitro cytotoxicity by use of mouse fibroblast L929 on UV-B blockers, NR assay was more excellent than MTT assay on quantitative

• Journal of Microbiology and Biotechnology
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• v.16 no.11
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• pp.1706-1712
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• 2006

Because of the need for new antimicrobial substances with novel mechanisms of action, we report here the use of an Acinetobacter reporter system for high-throughput screening of active antimicrobial agents. The bioreporter Acinetobacter strain DF4/PUTK2 carrying luciferase genes luxCDABE was chosen because of its ecological importance and it is widespread in nature. This bioreporter is genetically engineered to emit light constitutively that can be measured in real time by luminometry. Hence, this reporter system was employed to determine the bacteriostatic actions of spent-culture supernatants derived from twelve bacterial isolates. Out of the results, the strongest bioluminescence inhibitory effect of the supernatants was recorded with Bacillus cereus strain BAC (S5). Subsequently, ethyl acetate extracts of extracellular products of strain BAC (S5) were separated by a thin-layer chromatography (TLC). Based on the bioluminescence inhibitory assay, three fractions were found to have antimicrobial activity. One fraction (C) having the strongest antimicrobial activity was further purified using TLC and characterized by IR, $^1H$ NMR, mass spectrometry, SDS-PAGE, and amino acid composition analysis. The results predicted the presence of 2-pyrrolidone-S-carboxylic acid (PCA) and the octadeconic-acid-like fatty acid. Fraction C also demonstrated a broad inhibitory activity on several Gram-negative and Gram-positive bacteria. In conclusion, the Acinetobacter reporter system shows great potential to be a reliable, sensitive, and real-time indicator of the bacteriostatic actions of the antimicrobial agents.

• Journal of Microbiology and Biotechnology
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• v.20 no.10
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• pp.1397-1402
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• 2010

Papyriflavonol A (PapA), a prenylated flavonoid [5,7,3',4'-tetrahydroxy-6,5'-di-(${\gamma},{\gamma}$-dimethylallyl)-flavonol], was isolated from the root barks of Broussonetia papyrifera. Our previous study showed that PapA has a broad-spectrum antimicrobial activity against pathogenic bacteria and fungi. In this study, the mode of action of PapA against Candida albicans was investigated to evaluate PapA as an antifungal agent. The minimal inhibitory concentration (MIC) values were 10~25 ${\mu}g/ml$ for C. albicans and Saccharomyces cerevisiae, Gram-negative bacteria (Escherichia coli and Salmonella typhimurium), and Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus aureus). The kinetics of cell growth inhibition, scanning electron microscopy, and measurement of plasma membrane florescence anisotrophy revealed that the antifungal activity of PapA against C. albicans and S. cerevisiae is mediated by its ability to disrupt the cell membrane integrity. Compared with amphotericin B, a cell-membrane-disrupting polyene antibiotic, the hemolytic toxicity of PapA was negligible. At 10~25 ${\mu}g/ml$ of MIC levels for the tested strains, the hemolysis ratio of human erythrocytes was less than 5%. Our results suggest that PapA could be a therapeutic fungicidal agent having potential as a broad spectrum antimicrobial agent.

• Journal of Life Science
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• v.31 no.1
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• pp.83-89
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• 2021

Uu-ilys, an i-type lysozyme from spoon worm (Urechis unicinctus), is an innate immune factor that plays an important role in the defense against pathogens. It also possesses non-enzymatic antibacterial activity. Thus, there is a possibility to develop an antimicrobial model peptide from Uu-ilys. In this study, we report the design, production, and antibacterial activity of an Uu-ilys analog that exhibits antibacterial activity. The Uu-ilys structure was fragmented according to its secondary structures to predict the regions with antimicrobial activity using antimicrobial peptide (AMP) prediction tools from different AMP databases. A peptide containing the C-terminal fragment was predicted to exert antimicrobial activity. The chosen fragment was designated as an Uu-ilys analog containing the C-terminal fragment, Uu-ilys-CF. To examine the possibility of developing an AMP using the sequence of Uu-ilys-CF, recombinant fusion protein (TrxA-Uu-ilys-CF) was produced in an expression system that was heterologous. The produced fusion protein was cleaved after methionine leaving Uu-ilys-CF free from the fusion protein. This was then isolated through high performance liquid chromatography and reverse phase column, CapCell-Pak C18. The antibacterial activity of Uu-ilys-CF against different microbial strains (four gram-positive, six gram-negative, and one fungal strain) were assessed through the ultrasensitive radial diffusion assay (URDA). Among the bacterial strains tested, Salmonella enterica was the most susceptible. While the fungal strain tested was not susceptible to Uu-ilys-CF, broad spectrum antibacterial activity was observed.

• Applied Biological Chemistry
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• v.46 no.4
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• pp.385-390
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• 2003

An antimicrobial peptide was purified from the roots of Phytolacca americana L. and was designated as PAMP-r. Purification was carried out by DEAE-cellulose anion exchange, sephadex G-75 gel filtration, Mono S cation exchange, and Resource RPC reverse phage chromatography. The molecular weight of PAMP-r was estimated to be about 4,900 Da by 15% SDS-PAGE under reducing condition. PAMP-r exhibited a broad spectrum of antimicrobial activity. PAMP-r was stable against heat and pH treatment; its activity was not diminished by the heat treatment up to $80^{\circ}C$ for 30 min, and it showed a pH stability in the range between pH 3.0 to pH 8.0.

• Mycobiology
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• v.43 no.3
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• pp.303-310
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• 2015

The increasing emergence of lead drugs for the resistance produced by the pathogenic strains and arrival of new diseases have initiated the need for searching novel metabolites with best anticancer and antimicrobial properties than the existing one. With this view, the investigation was conducted for the isolation, identification, and biological evaluation of potential endophytic fungi of Aegle marmelos, a medicinal tree used for more than three decades, for curing various disorders. A total of 169 endophytic fungal strains obtained from sampling and among those 67 were pigmented strains. Upon antagonistic screening, five endophytic fungal strains exhibited antagonistic potentiality by inhibiting the pathogens. These five potent strains were characterized at molecular level by sequencing the amplified internal transcribed spacer (ITS) 1 and ITS 4 regions of rDNA and they were grouped under order Pleosporales, Eurotiales, and Capnodiales. The metabolites from the respective strains were produced in fungal culturing media and extracted using polar solvents. Further, the extracts of five endophytes manifested antimicrobial activity against tested clinical pathogens and Alternaria alternata (FC39BY), Al. citrimacularis (FC8ABr), and Curvularia australiensis (FC2AP) exhibited significant antimicrobial profile against 9 of 12 tested pathogens, showing broad spectrum activity. The antioxidant levels of all the five endophytes revealed the highest activity at least concentrations, and major activity was unveiled by the members of order Pleosporales FC2AP and FC8ABr. This research explains the value of endophytic fungal extracts and its significance of antimicrobial and antioxidant properties.

• Natural Product Sciences
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• v.25 no.1
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• pp.38-43
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• 2019

Microbial wound infection prolonged the hospitalization and increase the cost for wound management. Silver is commonly used as antimicrobial wound dressing. However, it causes several adverse side effects. Hence, this study was aimed to evaluate the antimicrobial efficiency of Swietenia macrophylla seed extract on clinical wound pathogens. Besides, the bioactive constituents of the seed extract were also determined. S. macrophylla seeds were extracted with methanol by maceration method. The seed extract inhibited 5 test bacteria and 1 yeast on disc diffusion assay. The antibacterial activity was broad spectrum, as the extract inhibited both Gram positive and Gram negative bacteria. On kill curve analysis, the antibacterial activity of the seed extract was concentration-dependent, the increase of extract concentration resulted in more reduction of bacterial growth. The extract also caused 99.9% growth reduction of Bacillus subtilis relative to control. A total of 21 compounds were detected in gas chromatography- mass spectrometry analysis. The predominant compounds present in the extract were oleic acid (18.56%) and linoleic acid (17.72%). In conclusion, the methanolic extract of S. macrophylla seeds exhibited significant antimicrobial activity on clinical wound pathogens. Further investigations should be conducted to purify other bioactive compounds from the seeds of S. macrophylla.

• Journal of Microbiology and Biotechnology
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• v.29 no.11
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• pp.1841-1851
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• 2019

Garcinol, a well-known medicinal phytochemical, was extracted and isolated from the dried fruit rinds of Garcinia quaesita Pierre. In this study, garcinol has successfully used to reduce silver ions to silver in order to synthesize garcinol-capped silver nanoparticles (G-AgNPs). The formation and the structure of G-AgNPs were confirmed by UV-visible spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The antimicrobial activity of garcinol and G-AgNPs were investigated by well diffusion assays, broth micro-dilution assays and time-kill kinetics studies against five microbial species, including Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). The formation of G-AgNPs is a promising novel approach to enhancing the biological activeness of silver nanoparticles, and to increase the water solubility of garcinol which creates a broad range of therapeutic applications.