• Korean Journal of Microbiology
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• v.52 no.2
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• pp.212-219
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• 2016

Forty-nine pigments were extracted from the collections of 106 pigment producing bacteria from the plant rhizosphere soil. Antibacterial activity test was performed in the subjects of the extracted pigments with plant pathogenic bacteria including Xanthomonas axonopodis and Xanthomonas campestris, and with plant pathogenic fungi including Botrytis cinerea, Colletotrichum acutatum, and Fusarium oxysporum. The yellow pigment by Chryseobacterium sp. RBR9 and the red pigment by of Methylobacterium sp. RI13 showed the antibacterial activities against Xanthomonas axonopodis and Xanthomonas campestris. The violet pigment by Collimonas sp. DEC-B5 showed the antibacterial activity as well as the antifungal activities against Botrytis cinerea and Fusarium oxysporum. Especially, the violet pigment inhibited the growth of Botrytis cinerea more than 65% at MIC $20{\mu}M$. Upon the HPLC analysis result for the isolation of pigment with antifungal activity, violacein (91.6%) and deoxyviolacein (8.4%) were isolated for the pigment by Collimonas sp. DEC-B5. The production amount of the pigment was increased more than 10 times higher when D-mannitol 1.5% and yeast extract 0.2% were added as the nitrogen source to SCB medium. This study suggests that produced violacein by Collimonas sp. DEC-B5 will be effective to control strawberry gray-mold rot fungi by its preventive activity.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.470-473
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• 2000

Since the biosynthetic production of indigo and indirubin normally reflects a difficult process including the toxicity of indole to microorganisms, only several bacterial strains have been exploited to produce indigo and indirubin from indole or its derivatives. P. savastanoi BCNU 106, which was a gram negative bacterium, was isolated and tolerant to 10% (v/v) toluene. The indole tolerance level of P. savastanoi BCNU 106 was as high as 160 mg/ml when toluene or p-xylene was added to the medium to 20% by volume. P. savastanoi BCNU 106 grown in a two-phase culture system containing indole(100 mg/ml) and P-xylene (0.2 ml/ml) produced P-xylene-soluble pigments, blue indigo and purple indirubin. Of the conditious tried, the production of indigo and indirubin was found only when P. savastanoi BCNU 106 was grown in the two-phase system overlaid with the organic solvents with appropriate polarity. This study may illustrate that the isolated extremophile P. savastanoi could be used in the microbial conversion process of the industrial potentials.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.08a
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• pp.83-90
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• 1999

Electron crystallography of two-dimensional crystalsand electron cryo-microscopy is becoming an established method for determining the structure and function of a variety of membrane proteins that are providing difficult to crystallize in three dimension. In this study this technique has been used to investigate the structure of a ~160 kDa reaction centre sub-core complex of photosystem II. Photosystem II is a photosynthetic membrane protein consisting of more than 25 subunits. It uses solar energy to split water releasing molecular oxygen into the atmosphere and creates electrochemical potential across the thylakoid membrane, which is eventually utilized to generate ATP and NADPH. Images were taken using Philips CM200 field emission gun electron microscope with an acceleration voltage of 200kW at liquid nitrogen temperature. In total, 79 images recorded dat tilt angles ranging from 0 to 67 degree yielded amplitudes and phases for a three-dimensional map with an in-plant resolution of 6$\AA$ and 11.4$\AA$ in the third dimension shows at least 23 transmembrane helices resolved in a monomeric complex, of which 18 were able to be assigned to the D1, D2, CP47 , and cytochrome b559 alfa beta-subunits with their associated pigments that ae active in electron transport (Rhee, 1998, Ph.D.thesis). The D1/D2 heterodimer is located in the central position within the complex and its helical scalffold is remarkably similar to that of the reaction centres not only in purple bacteria but also in plant photosystem I (PSI) , indicating a common evoluationary origin of all types of reaction centre in photosynthetic organism known today 9RHee et al. 1998). The structural homology is now extended to the inner antenna subunit, ascribed to CP47 in our map, where the 6 transmembrane helices show a striking structural similarity to the corresponding helices of the PSI reaction centre proteins. The overall arrangement of the chlorophylls in the D1 /D2 heterodimer, and in particular the distance between the central pair, is ocnsistent with the weak exciton coupling of P680 that distinguishes this reaction centre from bacterial counterpart. The map in most progress towards high resolution structure will be presented and discussed.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.5
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• pp.441-449
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• 2015

Flavonoids are plant pigments that have been demonstrated to exert various pharmacological effects including anti-cancer, anti-diabetic, anti-atherosclerotic, anti-bacterial, and anti-inflammatory activities. However, the molecular mechanisms in terms of exact target proteins of flavonoids are not fully elucidated yet. In this study, we aimed to evaluate the anti-inflammatory mechanism of scutellarein (SCT), a flavonoid isolated from Erigeron breviscapus, Clerodendrum phlomidis and Oroxylum indicum Vent that have been traditionally used to treat various inflammatory diseases in China and Brazil. For this purpose, a nitric oxide (NO) assay, polymerase chain reaction (PCR), nuclear fractionation, immunoblot analysis, a kinase assay, and an overexpression strategy were employed. Scutellarein significantly inhibited NO production in a dose-dependent manner and reduced the mRNA expression levels of inducible NO synthase (iNOS) and tumor necrosis factor (TNF)-${\alpha}$ in lipopolysaccharide (LPS)-activated RAW264.7 cells. In addition, SCT also dampened nuclear factor (NF)-${\kappa}B$-driven expression of a luciferase reporter gene upon transfection of a TIR-domain-containing adapter-inducing interferon-${\beta}$ (TRIF) construct into Human embryonic kidney 293 (HEK 293) cells; similarly, NF-${\kappa}B$ nuclear translocation was inhibited by SCT. Moreover, the phosphorylation levels of various upstream signaling enzymes involved in NF-${\kappa}B$ activation were decreased by SCT treatment in LPS-treated RAW264.7 cells. Finally, SCT strongly inhibited Src kinase activity and also inhibited the autophosphorylation of overexpressed Src. Therefore, our data suggest that SCT can block the inflammatory response by directly inhibiting Src kinase activity linked to NF-${\kappa}B$ activation.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1692-1700
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• 2017

Ralstonia solanacearum causes bacterial wilt in a wide variety of host plant species and produces a melanin-like blackish-brown pigment in stationary phase when grown in minimal medium supplemented with tyrosine. To study melanin production regulation in R. solanacearum, five mutants exhibiting overproduction of melanin-like pigments were selected from a transposon (Tn) insertion mutant library of R. solanacearum SL341. Most of the mutants, except one (SL341T), were not complemented by the original gene or overproduced melanins. SL341T showed Tn insertion in a gene containing a conserved domain of eukaryotic transcription factor. The gene was annotated as a hypothetical protein, given its weak similarity to any known proteins. Upon complementation with its original gene, the mutant strains reverted to their wild-type phenotype. SL341T produced 3-folds more melanin at 72 h post-incubation compared with wild-type SL341 when grown in minimal medium supplemented with tyrosine. The chemical analysis of SL341T cultural filtrate revealed the accumulation of a higher amount of homogentisate, a major precursor of pyomelanin, and a lower amount of dihydroxyphenylalanine, an intermediate of eumelanin, compared with SL341. The expression study showed a relatively higher expression of hppD (encoding hydroxyphenylpyruvate dioxygenase) and lower expression of hmgA (encoding homogentisate dioxygenase) and nagL (encoding maleylacetoacetate isomerase) in SL341T than in SL341. SL341 showed a significantly higher expression of tyrosinase gene compared with SL341T at 48 h post-incubation. These results indicated that R. solanacearum produced both pyomelanin and eumelanin, and the novel hypothetical protein is involved in the negative regulation of melanin production.

• Korean Journal of Food Science and Technology
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• v.5 no.1
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• pp.49-54
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• 1973

Studies were carried out to investigate the relationship of the remaining percentage of antiseptics and the preservative effect of combined antiseptics and gamma radiation on the keeping quality of pork sausage. Antiseptics quantities, total bacterial counts, and pH were examined during the storage at $5^{\circ}C$ and $30^{\circ}C$. The results obtained were summarized as follows: 1) After irradiation, quantities of antiseptics decreased in proportion to the level of dosage and K-SOA showed more radiosensitivity than AF-2 (p<0.01). 2) The remaining percentage of antiseptics during storage were higher in samples of more irradiated and stored at the lower temperature. AF-2 decreased less than K-SOA. 3) The correlation between the increase of total bacteria counts and percentage of antiseptics survival in sausage was highly significant(p<0.01). High doses of irradiation, storage at lower temperature and use of AF-2, however, seemed to be effective in controlling the increase of total bacterial flora. 4) From the relationships among quantities of antiseptics, number of total bacteria and sensory evaluation, it was shown that the most suitable radiation dose was considered to be 0.5 Mrad, which was superior to 0.75 Mrad in keeping qualities and nonirradiation odor. 5) Effect of gamma ray on the heme pigments of sausage surface was not recognized.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.193-200
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• 2007

Indoor airborne bacterial and fungal concentrations were examined at classrooms and corridors of 3 elementary schools in Ulsan. Airborne microorganisms were collected with an impaction-type air sampler using plate count agar and dichloran rose bengal chloramphenicol agar. During the semester, concentrations of bacteria ranged $168{\sim}3,887 MPN/m^3$ at classrooms and $168{\sim}6,339 MPN/m^3$ at corridors, while those of fungi ranged $34{\sim}389 MPN/m^3$ at classrooms and $91{\sim}507 MPN/m^3$ at corridors. The bacterial concentrations showed larger variations between situations and schools compared to those of fungi. When airborne bacteria were isolated and identified, 84% were observed as Gram-positive, and Micrococcus spp. was the most abundant group with 61% of tested isolates, followed by genus Staphylococcus with 10%. The Micrococcus spp. isolates, of which 75% were identified as M. luteus, appeared to be from human origins. The protective pigments and substantial cell wall of Micrococcus may provide selective advantage for their survival in the air. We also isolated and identified 15 genera of filamentous fungi. The most common culturable fungi were Cladosporium, Aspergillus and Penicillium, and these 3 genera were 69% of fungal isolates. Genus Stachybotrys, of which S. chartarum is a well known producer of many potent mycotoxins, was also detected from one of the schools. further systematic studies are necessary with an emphasis on species identification and mycotoxin production of isolated fungal genera, including Aspergillus, Penicillium, and Stachybotrys.

• Journal of Life Science
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• v.32 no.5
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• pp.411-419
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• 2022

Carotenoids are red, orange, and yellow fat-soluble pigments that exist in nature, and are known as physiologically active substances with various functions, such as provitamin A, antioxidant, anti-inflammatory, and anticancer. Because of their physiological activity and color availability, carotenoids are widely used in the food, cosmetics, and aquaculture industries. Currently, most carotenoids used industrially use chemical synthesis because of their low production cost, but natural carotenoids are in the spotlight because of their safety and physiologically active effects. However, the production of carotenoids in plants and animals is limited for economic reasons. Carotenoids produced by bacteria have a good advantage in replacing carotenoids produced by chemical synthesis. Since carotenoids produced from bacteria have limited industrial applications due to low productivity, studies are continuously being conducted to increase the production of carotenoids by bacteria. Studies conducted to increase carotenoid production from bacteria include the activity of enzymes in the bacterial carotenoid biosynthesis pathway, the development of mutant strains using physical and chemical mutagens, increasing carotenoid productivity in strain construction through genetic engineering, carotenoid accumulation through stress induction, fermentation medium composition, culture conditions, co-culture with other strains, etc. The aim of this article was to review studies conducted to increase the productivity of carotenoids from bacteria.