• Journal of Microbiology
• /
• v.43 no.5
• /
• pp.443-450
• /
• 2005

The multi-host pathogen, Pseudomonas aeruginosa, possesses an extraordinary versatility which makes it capable of surviving the adverse conditions provided by environmental, host, and, presumably, competing microbial factors in its natural habitats. Here, we investigated the P. aeruginosa-Bacillus subtilis interaction in laboratory conditions and found that some P. aeruginosa strains can outcompete B. subtilis in mixed planktonic cultures. This is accompanied by the loss of B. subtilis viability. The bactericidal activity of P. aeruginosa is measured on B. subtilis plate cultures. The bactericidal activity is attenuated in pqsA, mvfR, lasR, pilB, gacA, dsbA, rpoS, and phnAB mutants. These results suggest that P. aeruginosa utilizes a subset of conserved virulence pathways in order to survive the conditions provided by its bacterial neighbors.

• Korean Journal of Microbiology
• /
• v.15 no.1
• /
• pp.46-59
• /
• 1977

To screen biologically active components of the higher fungi of Korea, the carpophores of Auricularia polytricha, a well-known edible mushroom, were extracted with 0.14M NaCl solution. The extractive was successively fractionated by adding ammonium sulfate in various amounts, the respective precipitates being weparated by centrifugation, dialyzed and freeze-dried. When a dose of 60mg/kg of each was, i.p., injected into ICR mice, the fraction shich was precopitated at 20% (NH$_{4}$)$_{2}$SO$_{4}$ showed the highest toxicity, killing seven mice within two days. The fraction obtained at 40% (NH$_{4}$)$_{2}$SO$_{4}$ showed the second highest toxicity. The two fractions were named auratoxin I and II after the genus name. The symptoms of the intoxication were convulsion during the first 30 minutes after the injection, then sleeping within an hour, and tremor, lacrimation, nasal and ophthalmic bleeding, congestion and death in 24 hours. Particularly the spleen of the mice was fonud to be enlarged remarkably. The chemical analysis of the toxins showed that auratoxin I consisted of 4.4% protein and 84.5% polysaccharide and that auratoxin II 35.8% protein and 48.0% polysaccharide.

• Korean Journal of Microbiology
• /
• v.22 no.4
• /
• pp.223-228
• /
• 1984

To screen biologically active components of the higher fungi of Korea, the carpophores of Auricularia polytricha, a well-known edible mushroom, were extracted with 0.14M NaCl solution. The extractive was successively fractionated by adding ammonium sulfate in various amounts, the respective precipitates being weparated by centrifugation, dialyzed and freeze-dried. When a dose of 60mg/kg of each was, i.p., injected into ICR mice, the fraction shich was precopitated at 20% (NH/sub 4/)/sub 2/SO/sub 4/ showed the highest toxicity, killing seven mice within two days. The fraction obtained at 40% (NH/sub 4/)/sub 2/SO/sub 4/ showed the second highest toxicity. The two fractions were named auratoxin I and II after the genus name. The symptoms of the intoxication were convulsion during the first 30 minutes after the injection, then sleeping within an hour, and tremor, lacrimation, nasal and ophthalmic bleeding, congestion and death in 24 hours. Particularly the spleen of the mice was fonud to be enlarged remarkably. The chemical analysis of the toxins showed that auratoxin I consisted of 4.4% protein and 84.5% polysaccharide and that auratoxin II 35.8% protein and 48.0% polysaccharide.

• Mycobiology
• /
• v.32 no.4
• /
• pp.197-198
• /
• 2004

A new technique for single spore isolation was developed for predacious fungi forming constricting rings directly on the spores using Dactylaria brochopaga and Arthrobotrys dactyloides. Constricting rings were induced directly on the spores by transferring the spores in 25 ppm solution of DL-Valine in sterile distilled water. Freshly hatched and thoroughly washed second stage juveniles of Meloidogyne incognita were transferred into cavity blocks containing induced rings for trapping and killing of nematodes. The killed nematodes were surface sterilized with streptomycin and inoculated into petri dishes containing maize meal agar media with 100 ppm streptomycin. The petri dishes were incubated at $29{\pm}1^{\circ}C$ for few days which yielded axenic culture of these fungi.

• ALGAE
• /
• v.28 no.4
• /
• pp.297-305
• /
• 2013

There is increasing interest in the relationships between marine bacteria and red tide organisms. Some bacteria are known to kill red tide organisms, and may be responsible for accelerating the termination of red tides. Thus, certain algicidal bacteria have been proposed for the control of red tides. Meanwhile, many red tide organisms are known to feed on marine bacteria. The roles of marine bacteria and red tide organisms are therefore reversible. In Korean waters, the killing of red tide organisms by algicidal bacteria, and also the feeding of red tide organisms on marine bacteria have been extensively investigated. The findings of such studies may influence the conventional view of red tide dynamics, and also planktonic food webs. Here, we review the species and concentrations of algicidal bacteria that kill red tide organisms in Korean waters, as well as the ingestion rate and grazing impact of red tide organisms on marine bacteria. Furthermore, we offer an insight into the ecological roles of these 2 components in marine planktonic food webs.

• Korean Journal of Organic Agriculture
• /
• v.19 no.spc
• /
• pp.255-258
• /
• 2011

When kiwifruit root system infected with nematodes was treated by hot water dipping treatment, the maximum temperature for this treatment was suggested as $50^{\circ}C$. The lowest killing temperature of internal root-knot in the root tissue was $48^{\circ}C$. Consequently, root-knot nematodes could be killed without damaging root tissues by the hot water dipping treatment at $48^{\circ}C$ for 10 minutes. This could be useful for organic production and distribution of kiwifruit seedlings by avoiding the synthetic nematicides which are not easily decomposed in soil once applied.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.26 no.6
• /
• pp.998-1005
• /
• 1997

Kimchi showed protective effect from oxidative damage generated by hydrogen peroxide and paraquat. To investigate the major components of kimchi which reduce the cytotoxicity against reactive oxygen species, keratinocyte(A431, epidermoid carcinoma, human) and fibroblast(CCD-986SK, normal control, human) were cultured under oxidative stress condition provoked by paraquat, a superoxide anion generator, and hydrogen peroxide in the absence or presence of kimchi ingredients. Most keratinocyte and fibroblast cells were killed by hydrogen peroxide and paraquat over 1mM concentration, but kimchi ingredients showed protective effects from oxidative damage generated by hydrogen peroxide and onion, among those, garlic showed the most remarkable preventive effect. Most of kimchi ingredients showed protective effect against paraquat, especially leek notably increased cell survival. For fibroblast cells, ginger had the preventive effect against paraquat, especially leek notably increased cell survival. For fibroblast cells, ginger had the preventive effect from cell killing by high dose of hydrogen peroxide, but most ingredients were not effective against paraquat.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.9
• /
• pp.1073-1077
• /
• 1999

CRAMP, a 37-amino acid cationic antimicrobial peptide was recently deduced from the cDNA cloned from mouse femoral marrow RNA. In order to investigate the structure-activity relationship and functional region of CRAMP, CRAMP and its 18-mer overlapping peptides were synthesized by the solid phase method. CRAMP showed broad spectrum antibacterial activity against both Gram-positive and Gram-negative bacterial strains (MIC: 3.125-6.25 μM) but had no hemolytic activity until 50 μM. CRAMP was found to have a potent anticancer activity (IC50: 12-23 μM) against two human small cell lung cancer cell lines. Furthermore, CRAMP was found to display faster bactericidal rate in B. subtilis rather than E. coli in the kinetics of bacterial killing. Among 18-meric overlapping fragment peptides, only CRAMP (16-33) displayed potent antibacterial activity (MIC: 12.5-50 μM) against several bacteria with no hemolytic activity. Circular dichroism (CD) spectra anal-ysis indicated that CRAMP and its analogues will form the amphipathic α-helical conformation in the cell membranes similar to other antimicrobial peptides, such as cecropins and magainins.

• Journal of the Chungcheong Mathematical Society
• /
• v.24 no.3
• /
• pp.503-515
• /
• 2011

Let G be a compact connected semisimple Lie group, B the Killing form of the algebra g of G, and g the invariant metric induced by B. Then, we obtain a necessary and sufficient condition for a left invariant linear connection D with a Weyl structure ($D,\;g,\;{\omega}$) on (G, g) to be projectively flat (resp. Einstein-Weyl). And, we also get that if a left invariant linear connection D with a Weyl structure ($D,\;g,\;{\omega}$) on (G, g) which has symmetric Ricci tensor $Ric^D$ is projectively flat, then the connection D is Einstein-Weyl; but the converse is not true. Moreover, we show that if a left invariant connection D with Weyl structure ($D,\;g,\;{\omega}$) on (G, g) is projectively flat (resp. Einstein-Weyl), then D is a Yang-Mills connection.

• Journal of Microbiology and Biotechnology
• /
• v.31 no.6
• /
• pp.875-881
• /
• 2021

The mitochondrial targeting domain (MTD) of Noxa contributes to its mitochondrial localization and to apoptosis induction. As a peptide, MTD fused with octa-arginine (R8), a CPP, induces necrosis related to intracellular calcium influx and destruction of mitochondria and endoplasmic reticulum. We searched for homologs of MTD, and compared their cell killing capability when fused with R8. Three of the seven peptides triggered cell death with similar mechanisms. The comparative analysis of peptide sequences showed that four amino acid sites of MTD are critical in regulating necrosis, suggesting the potential to generate artificial, adjustable cytotoxic peptides, which could be effective medicines for many diseases. Thus, homologs functionality could hint to the functions of their belonging proteins.