• Korean Journal of Microbiology
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• v.31 no.4
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• pp.318-325
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• 1993

The optima] conditions for the formation, the regeneration. and the spheroplast fusion of Flavimonas aryz/habitans spheroplasts were investigated. Cells were transformed to spherop]asts effectively by treatment of 0.5% volume (v/v) of 0.] M EDTA and ]00 flg/ml lysozyme at $37^{\circ}C$ for 30 min without shaking. Magnesium chloride and calcium chloride were effective on the stabilization of spheroplasts. and 20 mM calcium chloride in the rich regeneration medium improve the yield of regenerants as much as 3.5-fo]d. Addition of 0.8% bovine serium albumine (BSA) in dilution buffer for spheroplast formation improved the stabilization of spheroplasts over extended periods (4-6 hr) at room temperature. and thus increased the yield of recombinants to 4.5-fold. The spheroplast formation frequency and regeneration frequency of F aryzihabitans strain was 90.10% and 3.800/." respectively. The first regenerated cell of F. aryzihabitans spheroplasts were appeared 6 hours after plating. By I I hours after plating, 80% of spheroplasts were regenerated on thc rich regeneration medium containing 0.5 M sucrose. The intraspeci11c spheroplast fusion of F urvz/habitans was carried out and the properties of obtained fusants were investigated. Formation of fusion products was effective when the Flav/munas spheroplast mixture was treated with 40%(w/v) PEG6000 and 20 mM CaCl, for 10 min at room temperature. and thc formation of frequency of recombinants were $2.0{\times}10^{-5}~3.6{\times}10^{-5}$. All tested recombinant clones were very stable on further propagation.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1379-1384
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• 2007

Four Gram-negative, chemoheterotrophic, non-motile, yellow-colored strains were isolated from the East Sea or from deep-sea sediments of Nankai Trough by standard dilution plating. Characterization by polyphasic approaches indicated that the four strains are members of the same species. Phylogenetic analyses based on 16S rRNA gene sequences revealed that the strains formed a coherent and novel genus-level lineage within the family Flavobacteriaceae. The dominant cellular fatty acids were i-C15:0, 3-OH i-C17:0, and 2-OH i-C15:0 and/or C16:1 ${\omega}7c$. Predominance of 2-OH i-C15:0 and/or C16:1 ${\omega}7c$ clearly differentiated the strains from closely related members. The DNA G+C contents ranged 35.1-36.2 mol%. It is proposed, from the polyphasic evidence, that the strains should be placed into a novel genus and species named Sufflavibacter maritimus gen. nov., sp. nov., with strain $IMCC1001^T(=KCCM\;42359^T=NBRC\;102039^T)$ as the type strain.

• Polymer(Korea)
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• v.27 no.3
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• pp.235-241
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• 2003

The polyacrylonitrile (PAN)-based activated carbon fibers (ACFs) containing copper metal were electrolytically prepared in introducing the antibacterial activity into ACFs. The antibacterial activity was investigated by dilution test against Staphylococous aureus (S. aureus; gram positive and virulence) and Klebsiella pnemoniae (K. pnumoniae: gram negative and avirulence). The micropore and textural properties of the ACFs containing copper metal were characterized by BET, t-plot, and H-K methods. The ACFs showed slight decreases in BET's specific surface area, micropore volume, and total pore volume as copper metal increased. However, the antibacterial activities of the ACFs were strongly increased against S. aureus as well as K. pnumoniae, which could be attributed to the presence of copper metal in CU/ACFs systems.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.168-175
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• 2007

We report here on the cultivation of numerous novel bacterial species from a eutrophic freshwater pond. A total of 60 strains, 15 strains per each culture medium, were obtained from the surface of a eutrophic freshwater pond by employing a conventional dilution-plating method with four different kinds of culture media, including R2A, 1/10R2A, PCA, and 1/10PCA. Among the 60 strains isolated, 27 strains showed less than 97% 16S rRNA gene sequence similarities to validly published species, and thus they are considered to comprise 19 novel species. Of the 27 strains assigned to the novel species, the majority of the strains (20 strains) were affiliated with the Alphaproteobacteria and Betaproteobacteria. The remaining 7 strains were affiliated with the Gammaproteobacteria, Firmicutes, Actinobacteria, and Deinococci. Because we have isolated 19 novel species from a usual freshwater pond using a conventional culturing technique, our results suggest that an unexplored ecosystem, even if it looks like a common ecosystem found elsewhere, harbors diverse unidentified microbes, which will be definitely further characterized.

• The Plant Pathology Journal
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• v.21 no.3
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• pp.244-251
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• 2005

The induction of growth promotion on numerous crops by rhizobacteria is a well documented phenomenon. In case of tomato (Lycopersicon esculentum), fruit yield is higher in replant soil than that in fresh soil. To investigate what kind of rhizobacterium is involved, microbial community in rhizosphere and on rhizoplane of tomato plants from each soil was analyzed by dilution plating on selective media. Many Gram-negative bacteria and actinomycetes were isolated from tomato in replant soil. One Gram-negative rhizobacterium isolated was identified as Pseudomonas putida based on its biochemical characteristics, fatty acid methyl ester analysis and 16S rDNA sequence. This bacterium designated strain 17 inhibited the growth of Pseudomonas corrugata, and increased growth of tomato seedlings. In addition, its culture filtrate inhibited conidial germination of plant-pathogenic fungi such as Fusarium oxysporum f. sp. radicis-lycopersici, F. oxysporum f. sp. cucumerinum, and Nectria radicicola. Scanning electron microscopy revealed strain 17 colonized and persisted on the epidermal surfaces of tomato radicles and roots. These results suggest that P. putida strain 17 may serve as a biological control agent to suppress multiple soil-borne diseases for tomato plants. Increased microbial populations that suppress deleterious microorganisms including pathogens could be one of the major factors in increased tomato yield in replant soil.

• The Plant Pathology Journal
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• v.24 no.3
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• pp.283-288
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• 2008

Plant leaf surface is an important niche for diverse epiphytic microbes, including bacteria and fungi. Plant leaf surface plays a critical frontline defense against pathogen infections. The objective of our study was to evaluate the effectiveness of a starch-based super-absorbent polymer(SAP) combination, which enhances water potential and nutrient availability to plant leaves. We evaluated the effect of SAP on the maintenance of bacterial populations. In order to monitor bacterial populations in situ, a SAP mixture containing Pseudomonas syringae pv. tabaci that expressed recombinant green fluorescent protein(GFPuv) was spray-challenged onto whole leaves of Nicotiana benthamiana. The SAP combination treatment enhanced bacterial robustness, as indicated by disease severity and incidence. Unexpectedly, bacterial numbers were not significantly different between leaves treated with the SAP combination and those treated with water alone. Furthermore, young leaves treated with the SAP combination had more severe symptoms and a greater number of bacterial spots caused by primary and secondary infections compared to young leaves treated with the water control. In contrast, bacterial cell numbers did not statistically differ between the two groups, which indicated that measurement of viable GFP-based bacterial spots may provide a more sensitive methodology for assessing virulence of bacterial pathogens than methods that require dilution plating following maceration of bacterial-inoculated leaf tissue. Our study suggests that the SAP combination successfully increased bacterial aggressiveness, which could either be used to promote the ability of biological agents to control weedy plants or increase the robustness of saprophytic epiphytes against competition from potentially harmful microbes.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.569-573
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• 2010

A quantitative detection method for Salmonella in seafood was developed using a SYBR Green-based real-time PCR assay. The assay was developed using pure Salmonella DNA at different dilution levels [i.e., 1,000 to 2 genome equivalents (GE)]. The sensitivity of the real-time assay for Salmonella in seeded seafood samples was determined, and the minimum detection level was 20 CFU/g, whereas a detection level of 2 CFU/ml was obtained for pure culture in water with an efficiency of ${\geq}85%$. The real-time assay was evaluated in repeated experiments with seeded seafood samples and the regression coefficient ($R^2$) values were calculated. The performance of the real-time assay was further assessed with naturally contaminated seafood samples, where 4 out of 9 seafood samples tested positive for Salmonella and harbored cells <100 GE/g, which were not detected by direct plating on Salmonella Chromagar media. Thus, the method developed here will be useful for the rapid quantification of Salmonella in seafood, as the assay can be completed within 2-3 h. In addition, with the ability to detect a low number of Salmonella cells in seafood, this proposed method can be used to generate quantitative data on Salmonella in seafood, facilitating the implementation of control measures for Salmonella contamination in seafood at harvest and post-harvest levels.

• Journal of Korean society of Dental Hygiene
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• v.14 no.1
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• pp.95-100
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• 2014

Objectives : The purpose of the present study was to investigate the effect of bamboo charcoal on Streptococcus mutans which is one of the most important causative agents of dental caries. Methods : S. mutans was incubated with or without bamboo charcoal and then changes were observed in its cell viability and antibacterial effect. Oral epithelial cells viabillity(human gingival fibroblast, HGF) was performed using MTT assay. Antibacterial effect was analyzed using a dilution plating method and agar diffusion method. Results : Oral epithelial cells, human gingival fibroblast (HGF) showed a tendency to increase in bamboo charcoal treatment solution concentrations(0.5, 1, 2, 3, 5, 10%). The bamboo charcoal had an antibacterial effect on S. mutans. Antibacterial effect of bamboo charcoal for the bacterium was 58%. Charcoal concentration of 2% and 5% in the inhibition zone showed a minimal growth, but the concentration of 10% bamboo charcoal in inhibition zone revealed a conspicuous antibacterial activity. Conclusions : Overall results suggested that the bamboo charcoal proved to be bactericidal effect on S. mutans.

• Mycobiology
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• v.43 no.4
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• pp.392-401
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• 2015

Using dilution plating method, 47 fungal isolates were obtained from a soil sample collected from Dokdo in the East Sea of Korea in 2013. In this study, two fungal isolates, EML-MFS30-1 and EML-DDSF4, were confirmed as undescribed species, Metarhizium guizhouense and Mortierella oligospora in Korea based on current classification system using multi loci including rDNA internal transcribed spacer, large subunit, small subunit, and ${\beta}$-tubulin (BTUB) genes. Herein, detailed morphological descriptions on characters of the undescribed fungal species as well as their molecular phylogenetic status are provided with comparisons to related species.

• Korean Journal of Microbiology
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• v.54 no.1
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• pp.81-83
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• 2018

We sequenced the genome of the Neisseria sp. KEM232 isolated from the smooth surface caries of human cavity of a 7-year old male in Republic of Korea by using the standard dilution plating technique. The genome comprises a single circular 2,371,912 bp chromosome with a G + C content of 58.5%, 2,210 protein-coding genes, 108 pseudo genes, 51 RNA genes, and one CRISPR array. Based on the 16S rRNA gene sequence similarity and average nucleotide identity, the strain KEM232 is most closely related to Neisseria baciliformis.