• The Korean Journal of Ecology
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• v.27 no.5
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• pp.301-306
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• 2004

The sensitivity to Cd of three ectomycorrhizal fungi, Paxillus involutus, Suillus bovinus and Rhizopogon subcaerulescens, was assessed and compared in terms of radial growth and dry mass production, using both agar and liquid culture. The radial growth of S. bovinus and R. subcaerulescens was significantly reduced at the lowest concentration (0.1mg Cd/L). The 50% effective concentration (EC$_{50}$) values calculated from radial growth rates of the ectomycorrhizal fungi showed that the sensitivity of the fungi to Cd was greatest in S. bovinus and lowest in R. subcaerulescens. Cadmium addition also significantly decreased dry mass production of the ectomycorrhizal fungi. The sensitivity of the fungi to Cd in terms of dry mass production, was greatest in S. bovinus and lowest in P. involutus. Higher growth rates of P. involutus and melanisation of R. subcaerulescens appeared to contribute to reduced Cd toxicity.

• Microbiology and Biotechnology Letters
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• v.27 no.6
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• pp.509-514
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• 1999

Forty seven amylolytic Bifidobacterium strains were isolated on starch-containing agar medium from the faecal samples of the various age groups of Korean. From these amyloytic Bifidobacterium spp., two strains of KFRI 1535, identified temporarily as Bifidobacterium longum, and KFRI 1550, identified as Bifidobacterium breve, showed great macrophage-stimulating activity for the production of tumor necrosis factor-$\alpha$ and inteleukin-6. As the cell concentration increased the cytokine production increased, although in some strains the cytokine levels started to decline over cell concentration increased the cytokine production increased, although in some strains the cytokine levels started to decline over cell concentration of $250\mu\textrm{g}$/ml. the strains which showed high cytokine-stimulating activity generally showed greater production of nitric oxide even though differences were less between strains. Selected Bifidobacterium strains were compared for their fermentation capability in saccharified rice solution and in apple pomace mixture.

• Journal of agriculture & life science
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• v.44 no.3
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• pp.23-30
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• 2010

The optimal growth condition of in vitro stem cutting of Dendrobium nobile 'Hamana Lake Dream' ${\times}$ 'No. 55' was investigated. Among various media and their concentrations, MS media had better effect on the growth of micro stem cutting than Hyponex media in all concentration levels except stem length. The activated charcoal concentration in MS media showed different effects on number of stem and root, leaf length, and fresh weight: the most effective in the range of 0.1 to 1.0 g/L and barely effective above 2.0 g/L. Addition of agar 5 g/L, sucrose at 40 g/L, and peptone at 1 g/L to MS media increased significantly stem length, leaf width, and fresh weight, internode length and number of roots, and the number of stem and leaves. On the other hand, addition of gelite with any concentration had no effect on the growth of micro stem cutting compare to that of control. The optimal temperature for growth of micro stem cutting was $28^{\circ}C$. Under the same temperature, MS medium was better than Hyponex medium for the growth of stem. In addition, sucrose at 40 g/L was the most effective on growth at $28^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.79-84
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• 1992

The Photosynthetic bacterium, Rhodopseudomonas sphaeroides strain B6 was irnmobilized on agar gel. The optimum concentration of agar for hydrogen production was 2% (w/v). Maximum rates of hydrogen production by immobilized (300 ml of gel; 2.85 rng dry cells/ml) and free cells (1l culture; 0.87 mg dry cells/ml) were 47.5 and 48.0 ml/hr/culture, respectively. However, when both cultures were fed by 10 mmoles of lactate as limited electron donor at the later period of incubation, the activity of hydrogen production by free cells was significantly decreased but, immobilized cells continued hydrogen production with almost the same initial rate. Wc examined hydrogen production by immobilized cells of strain B6 under periodic illumination for 12 hr-intervals. When the culture was periodically fed by basal medium containing 9.3 rnmoles of DL-lactate and 1.86 mmoles of L-glutamate as consumed electron donor and nitrogen source, respectively, for every one liter of hydrogen produced, hydrogen was evolved continuously with the average rate of 510 ml/day/300 ml gel (2.9 rng dry cellslml) during the incubation time for 228 hr.

• Journal of fish pathology
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• v.36 no.2
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• pp.251-261
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• 2023

Photobacterium sp. YW2207 was isolated from rainbow trout raised in a fish farm located in Yeongwol-gun, Gangwon Province, South Korea. Based on 16S rRNA sequence analysis and phylogenetic analysis, it was confirmed that Photobacterium sp. YW2207 showed 100% similarity with Photobacterium piscicola and Photobacterium phosphoreum, and 94.6% similarity with P. damselae subsp. damselae. Biochemical analysis revealed that Photobacterium sp. YW2207 is a Gram-negative, motile bacterium with a cell size of 1.5~3×3~5 ㎛. The bacteria were cultured on nutrient agar, brain heart infusion agar, Muller-Hinton agar, tryptic soy agar, and thiosulfate citrate bile sucrose agar with NaCl concentrations ranging from 0 to 2.5%. The API50CHE and API20E tests indicated lower utilization capabilities compared to the P. damselae strains provided in the API database. Furthermore, unlike most Photobacterium species, Photobacterium sp. YW2207 presented negative for catalase test. Results from the flow cytometric measurement indicated that Photobacterium sp. YW2207 exhibited a more diverse distribution of cell sizes and had larger cell sizes compared with P. damselae subsp. damselae. Minimum inhibitory concentration tests showed that Photobacterium sp. YW2207 had low susceptibility to β-Lactam and aminoglycoside antibiotics, while having high susceptibility to tetracycline, doxycycline, and quinolone antibiotics. Pathogenicity on rainbow trout revealed that an immersion of 1×10⁵ CFU/ml did not cause mortality or clinical symptoms.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.619-623
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• 1991

To investigate nisin production and resistance of Lactococcus lactis ssp. tactis ML (L. lactis $ML_8$, effects of medium, pH of culture broth, and cell growth on the nisin activity, and effect of nisin with or without $Ca^[2+}$ ion on the growth of L. lactzs were analyzed. In the bio-assay of nisin by the agar diffusion method, inhibition-zone diameter of Micrococcus Javus was propotional to the logarithm of nisin concentration ranged 0.5~20 unitlml (12.5~500 ng/mf). Nisin activity of the pasteurized culture filtrates of L. lactis MLs was high at pH 2!3 but was inactivated completely at pH over 6.0. Nisin production of the L. lactis $ML_8$ cultured on LTB broth increased at late logarithmic phase and reached 10.5 unitlml after 16 hr. The cell growth of L. lactis LM 0230, a plasmid free and nisin sensitive strain, was inhibited on agar medium containing 7 unitlrnl of nisin, while L. lactis $ML_8$ showed high survival ability at 20 unitld of nisin. When 40 mM $Ca^[2+}$ ion was added to Elliker broth with 8 unitlml of nisin, the growth pattern of L. lactis $ML_8$ was similiar to that on control medium which did not contain nisin and $Ca^[2+}$ ion, and this suggested that $Ca^[2+}$ increased the nisin resistance of the L. lactis.

• Fashion & Textile Research Journal
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• v.5 no.1
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• pp.71-76
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• 2003

Three different types of chitosan were prepared from red crab shells to study anti-microbial activity of chitosan on pathogenic bacteria, MRSA(Methicillin-resistant. Staphylococcus aureus), Water-insoluble chitosan, whose degree of deacetylation is kept over 90% and molecular weights are 20,000, 500,000, 150,000, 80,000, and 40,000, respectively. Water-soluble chitosan, whose degree of deacetylation is about 48% and molecular weights are 200,000 and 80,000. Water-soluble chitosan, whose degree of deacetylation is 82% and molecular weight is 3,900. The anti-microbial activities of three types of chitosan were investigated by Tube Dilution Technique(TDT) and Agar Plate Smear Method(APSM). And the following conclusions are made ; Chitosan having 5 different types of M.W chitosan (over 90% deacetylation) showed similar anti-microbial activities at over 0.05% concentration. Especially, chitosan having M.W 40,000 150,000 showed the excellent anti-microbial activity. The anti-microbial activity of chitosan was enhanced when the chitosan/acetic add solution was aged for 7days. The anti-microbial activity of chitosan was only shown at chitosan/acetic acid solution. The anti-microbial activity was not detected in chitosan solution dissolved in neutral pH water. Therefore, it can be concluded that the anti-microbial activity was due to NH3+ cationic ion of chitosan in acidic aqueous solution.

• Journal of Life Science
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• v.8 no.5
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• pp.520-525
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• 1998

Effects of plant growth regulators and anti-oxidants for rapid multiplication of Cymbidium kanran were investigated. The best gelling agent was 2.5 g/1 gelrite which needed less quantity (about 28%) and half price than 9 g/1 chemi-cal agar. Undefined edible agar was only a little bit worse than chemical agar in growth, but the price was half as much as the latter. The higher concentration of BA and NAA, the deeper browning of medium that prevented from performing its functions of plant growth regulators. Polyvinylpyrrolidone (M.W. 40,000) was the most effective anti-oxidant other than ascorbic acid, aspartic acid, and rutin in protecting the browning of medium, enhancing the effect of plant growth regulators, and thus prolonging the subculture cycle. Vigorous seedlings were obtained by 0.1∼1.0 mg/1 BA,0.1 mg/1 NAA and 1 g/1 polyvinylpyrrolidone treatments. Therefore, the best result for growth and econo-mic aspects in rhizome culture of Cymbidium kanran were obtained by using MS basal medium with 2.5 g/1 gelrite, 1 g/1 polyvinylpyrrolidone, 0.1∼1.0 mg/1 BA and 0.1 mg/1 NAA.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.1
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• pp.21-25
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• 2013

Acinetobacter baumannii is an aerobic, gram-negative and glucose-non-fermenting bacterium, which has emerged as a serious opportunistic pathogen. Many clinical microbiology laboratories use the Vitek 2 system for the routine antimicrobial susceptibility testing process, including testing on A. baumannii isolates. However, in case of amikacin, it is now recommended to perform additional antimicrobial susceptibility testing for A. baumannii strains due to the relatively lower minimum inhibitory concentration (MIC) in the Vitek 2 system compared to conventional reference methods. In our study, we assessed MIC for amikacin susceptibility testing of A. baumannii isolates in the Vitek 2 system, the agar dilution, Etest, and disk diffusion method. We collected 40 gentamicin-resistant, A. baumannii strains (amikacin MIC by Vitek 2:${\leq}2{\mu}g/mL$, 2 isolates; $4{\mu}g/mL$, 34 isolates; $8{\mu}g/mL$, 4 isolates) from a University hospital and compared the Vitek 2 system to other reference methods for testing susceptibility to amikacin. The Vitek 2 system showed major errors in all of the 40 isolates, yielding a low MIC. The results of our study strongly suggested that the Vitek 2 system was not a reliable method to test the MICs of gentamicin; ranging from ${\geq}16{\mu}g/mL$ for amikacin susceptibility. Other tests, such as agar dilution, Etest, or disk diffusion methods, should be paralleled to determine the MIC of amikacin in A. baumannii.

• Korean Journal of Veterinary Research
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• v.39 no.4
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• pp.765-771
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• 1999

Unlike most Escherichia coli strains, E coli O157 : H7 didn't ferment sorbitol within 24h of incubation and showed a negative reaction for $\beta$-glucuronidase. We developed a new medium for the rapid isolation of E coli O157 : H7 using sorbitol MacConkey agar with cefixime, potassium tellurite and 4-methylumbelliferyl-${\beta}$-D-glucuronide (MUG) as a primary plating medium. The addition of $20{\mu}g/ml$ of vancomycin in enrichment broth for E coli O157 : H7 inhibited lots of Gram positive bacteria. Three strains (10.3%) of 29 non-O157 E coli strains and 3 strains (8.3%) of 36 Salmonella spp were inhibited at the $0.05{\mu}g/ml$ of cefixime and 23 strains (79.3%) of 29 non-O157 E coli strains and 12 strains (33.3%) of 36 Salmonella spp were inhibited at the $2.0{\mu}g/ml$ of potassium tellurite. But none of the E coli O157 : H7 was affected at these concentration. The addition of MUG at $100{\mu}g/ml$ level to sorbitol MacConkey agar with cefixime and potassium tellurite (CTM-SMAC) aided in the rapid isolation of E coli O157 : H7 from samples by checking sorbitol-negative and $\beta$-glucuronidase negative phenotypes simultaneously. In conclusion, inoculation of a positive in the O157 screening test from enrichment broth on CTM-SMAC appeared to be a rapid, cost-effective and sensitive method for the isolation of E coli O157 : H7.