• Journal of Microbiology and Biotechnology
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• v.19 no.3
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• pp.250-256
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• 2009

Acinetobacter strain $KNF2022^T$ was isolated from tobacco plant roots during the screening of antiviral substances having inhibitory effects on Tobacco mosaic virus (TMV) and examined by phenotypic, chemotaxonomic, and genetic characterization. It was a nonmotile, Gram-negative bacterium. This strain contained Q-9 as the main respiratory quinone. The major cellular fatty acids of the isolate were 16:0, 18:1 w9c, and 16:1 w7c/15 iso 2OH. The DNA base composition was 44 mol%. Phylogenetic analysis based on the 16S rRNA sequence revealed that the isolate formed an evolutionary lineage distinct from other Acinetobacter species. Based on the evaluation of morphologic, physiologic, and chemotaxonomic characteristics, DNA-DNA hybridization values, and 16S rRNA sequence comparison, we propose the new species Acinetobacter antiviralis sp. nov., the type strain of which is $KNF2022^T$ (=KCTC $0699BP^T$).

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.666-674
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• 2016

The bacterial strains were screened as potential starters for fermenting low-salt doenjang (a Korean traditional fermented soybean paste) using Korean doenjang based on proteolytic and antipathogenic activities under 6.5-7.5% NaCl conditions. Phylogenetic analysis based on 16S rRNA gene sequences showed that they all belonged to the genus Bacillus. Proteolytic and antipathogenic activities against Escherichia coli, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, and Aspergillus flavus, as well as fibrinolytic, amylase, and cellulase activities of the 10 strains were quantitatively evaluated. Of these, strains D2-2, JJ-D34, and D12-5 were selected, based on their activities. The functional, phenotypic, and safety-related characteristics of these three strains were additionally investigated and strains D2-2 and D12-5, which lacked antibiotic resistance, were finally selected. Strains D2-2 and D12-5 produced poly-γ-glutamic acid and showed various enzyme activities, including α-glucosidase and β-glucosidase. Growth properties of strains D2-2 and D12-5 included wide temperature and pH ranges, growth in up to 16% NaCl, and weak anaerobic growth, suggesting that they facilitate low-salt doenjang fermentation. Strains D2-2 and D12-5 were not hemolytic, carried no toxin genes, and did not produce biogenic amines. These results suggest that strains D2-2 and D12-5 can serve as appropriate starter cultures for fermenting low-salt doenjang with high quality and safety.

• Journal of Microbiology and Biotechnology
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• v.24 no.12
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• pp.1679-1684
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• 2014

Acetobacter sp. strains were isolated from traditional vinegar collected in Daegu city and Gyeongbuk province. The strain KJY8 showing a high acetic acid productivity was isolated and characterized by phenotypic, chemotaxonomic, and phylogenetic inference based on 16S rRNA sequence analysis. The chemotaxonomic and phylogenetic analyses revealed the isolate to be a strain of Acetobacter pomorum. The isolate showed a G+C content of 60.8 mol%. It contained $\small{LL}$-diaminopimelic acid ($\small{LL}$-$A_2pm$) as the cell wall amino acid and ubiquinone $Q_9$ (H6) as the major quinone. The predominant cellular fatty acids were $C_{18:1}w9c$, w12t, and w7c. Strain KJY8 grew rapidly on glucose-yeast extract (GYC) agar and formed pale white colonies with smooth to rough surfaces. The optimum cultivation conditions for acetic acid production by the KJY8 strain were $20^{\circ}C$ and pH 3.0, with an initial ethanol concentration of 9% (w/v) to produce an acetic acid concentration of 8% (w/v).

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.415-424
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• 2010

The purpose of this study was to investigate the relationship between the global regulatory mechanism known as quorum sensing and expression of virulence factors in Escherichia coli O157:87. A nonpolar luxS deletion was introduced into the chromosome of strain CI03J, a human clinical isolate from South Korea, to create the ${\Delta}luxS$ mutant strain ML03J. Phenotypic characterization of wild-type and mutant strains demonstrated that ML03J had no obvious growth or metabolic defects on 0.2% glucose LB medium, produced a functionally defective flagellum, and could not utilize sorbose; the biological significance of sorbose utilization is unknown. Omics-based analysis revealed the involvement of LuxS in the transcriptional activation of several flagella/chemotaxisrelated genes (flhD; fliA, C, D, S, Z; and cheA, Y, Z), repression of glutamate-dependent acid resistance genes (gadAB), and expression of virulence factors including Shiga toxin, hemolysin, and SepD within the LEE pathogenicity island.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.243-249
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• 2017

An agar-degrading bacterium, designated as the GNUM08123 strain, was isolated from samples of red algae collected from the Yongil Bay near East Sea, Korea. The isolated GNUM08123 strain was gram-negative, aerobic, motile, and beige-pigmented, with $C_{16:0}$ (25.9%) and summed feature 3 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}2-OH$, 34.4%) as its major cellular fatty acids. A similarity search based on the 16S rRNA gene sequence revealed that it belonged to class Gammaproteobacteria and shared 97.7% similarity with the type strain Vibrio chagasii $R-3712^T$. The DNA G+C content of strain $GNUM08123^T$ was 46.9 mol%. The major isoprenoid quinone was ubiquinone-8. The results of DNA-DNA relatedness and 16S rRNA sequence similarity analyses, in addition to its phenotypic and chemotaxonomic characteristics, suggest that strain GNUM08123 is a novel species within genus Vibrio, designated as Vibrio sp. GNUM08123. Agarase production by strain GNUM08123 was induced by agar and sucrose, but was repressed probably owing to carbon catabolite repression by glucose and maltose.

• Korean Journal of Microbiology
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• v.41 no.2
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• pp.117-124
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• 2005

Two bacterial isolates obtained from rotifer and diseased olive flounder larvae, Paralichthys olivaceus, were identified as Vibrio ichthyoenteri based on the results of phenotypic characterization. In an attempt to develop rapid PCR method for the detection of V. ichthyoenteri, we examined the 16S-23S rRNA intergenic spacer region(ISR) of V. ichthyoenteri and developed species-specific primer for V. ichthyoenteri. Analysis of the ISR sequences showed that V. ichthyoenteri contains one type of polymorphic ISRs. The size of ISRs was 348 bp length and did not contain tRNA genes. Mutiple alignment of representative sequences from different V. species revealed several domains of high sequence variability, and allowed to design species-specific primer for detection of V. ichthyoenteri. The specificity of the primer was examined using genomic DNA prepared from 19 different V. species, isolated 18group Vibrio species and most similar sequence of other known Vibrio species. The results showed that the PCR reaction using species-specific primer designed in this study can be used to detect V. ichthyoenteri.

• BMB Reports
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• v.32 no.1
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• pp.6-11
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• 1999

To understand the function of phospholipids and their fatty acid composition on the morphological changes in the amp 1-4 mutant of Arabidopsis, the mutant was compared to the wild-type Arabidopsis by TLC, HPTLC, phosphorous assay, HPLC, and GC. In the mutant, phosphatidylethanolamine (PE) was increased 5-fold and phosphatidylglycerol (PG) was decreased 1.2-fold (nmol phosphorous/g tissue). Inositol phospholipids showed a generally increased trend ranging from 1.4-to 3.0-fold (nmol inositol/g tissue). When fatty acid composition of the mutant was compared to the wild-type, linoleic (18:2) and linolenic (18:3) acids of phosphatidylcholine (PC) and PG were decreased but palmitoleic acid (16:1) and oleic acid (18:1) of PC was increased 2.5- and 2.1-fold (mol%), respectively. In galactolipids, myristic acid (14:0) of monogalactosyl-diacylglycerol (MGDG) were increased 5.8-fold (mol%). Among the inositol phospholipids, lysophosphatidylinositol (L-PI) and phosphatidylinositol 4,5-bisphosphate ($PIP_2$) showed 4-and 1.9-fold (mol%) increase of 16:1, respectively. These results suggest that the increase of PE, the decrease of PG, the increase of inositol phospholipids, and the altered fatty acid composition are related to the phenotypic changes affecting the morphological features, and might cause different physiological changes in the amp 1-4 mutant compared to wild-type Arabidopsis.

• Journal of Preventive Medicine and Public Health
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• v.50 no.2
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• pp.127-132
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• 2017

Objectives: The aim of this study was to determine the prevalence of asymptomatic carriers of group A ${\beta}-hemolytic$ streptococci (GAS) in children living in a rural community and to investigate the association between episodes of acute pharyngitis and carrier status. Methods: Throat swabs were collected from September to November 2013 among children 5-13 years of age from a rural community (Maria Ignacia-Vela, Argentina). The phenotypic characterization of isolates was performed by conventional tests. Antimicrobial susceptibility was assayed for penicillin, tetracycline, chloramphenicol, erythromycin, and clindamycin (disk diffusion). The minimum inhibitory concentration was determined for penicillin, cefotaxime, tetracycline, and erythromycin. Results: The carriage of ${\beta}-hemolytic$ streptococci was detected in 18.1% of participants, with Streptococcus pyogenes in 18 participants followed by S. dysgalactiae ssp. equisimilis in 5. The highest proportion of GAS was found in 8 to 10-year-old children. No significant association between the number of episodes of acute pharyngitis suffered in the last year and the carrier state was detected (p>0.05). Tetracycline resistance (55.5%) and macrolide-resistant phenotypes (11.1%) were observed. Resistance to penicillin, cefotaxime, or chloramphenicol was not expressed in any streptococcal isolate. Conclusions: The present study demonstrated significant throat carriage of GAS and the presence of group C streptococci (S. dysgalactiae ssp. equisimilis) in an Argentinian rural population. These results point out the need for continuous surveillance of GAS and non-GAS carriage as well as of antimicrobial resistance in highly susceptible populations, such as school-aged rural children. An extended surveillance program including school-aged children from different cities should be considered to estimate the prevalence of GAS carriage in Argentina.

• The Plant Pathology Journal
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• v.35 no.6
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• pp.543-552
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• 2019

Fusarium asiaticum of the F. graminearum species complex causes head blight in small-grain cereals. The nivalenol (NIV) chemotypes of F. asiaticum is more common than the deoxynivalenol (DON) chemotypes of F. asiaticum or F. graminearum in Korea. To understand the prevalence of F. asiaticum-NIV in Korean cereals, we characterized the biological traits of 80 cereal isolates of F. asiaticum producing NIV or 3-acetyl-deoxynivalenol (3-ADON), and 54 F. graminearum with 3-ADON or 15-acetyl-deoxynivalenol (15-ADON). There was no significant difference in mycelial growth between the chemotypes, but F. asiaticum isolates grew approximately 30% faster than F. graminearum isolates on potato dextrose agar. Sexual and asexual reproduction capacities differed markedly between the two species. Both chemotypes of F. graminearum (3-ADON and 15-ADON) produced significantly higher numbers of perithecia and conidia than F. asiaticum-NIV. The highest level of mycotoxins (sum of trichothecenes and zearalenone) was produced by F. graminearum-3-ADON on rice medium, followed by F. graminearum-15-ADON, F. asiaticum-3-ADON, and F. asiaticum-NIV. Zearalenone levels were correlated with DON levels in some chemotypes, but not with NIV levels. Disease assessment on barley, maize, rice, and wheat revealed that both F. asiaticum and F. graminearum isolates were virulent toward all crops tested. However, there is a tendency that virulence levels of F. asiaticum-NIV isolates on rice were higher than those of F. graminearum isolates. Taken together, the phenotypic traits found among the Korean F. asiaticum-NIV isolates suggest an association with their host adaptation to certain environments in Korea.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.23-23
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• 2017

Rice (Oryza sativa L.) is the world's most important cereal crop. In crop plant, chlorophyll content and leaf senescence could affect grain filling and yield. We analyzed a QTL associated with chlorophyll content and delayed leaf senescence using high chlorophyll near isogenic line (HC-NIL). HC-NIL derived from a cross between Oryza sativa cv. Hwaseong as a recurrent parent and wild species O. grandiglumis as a donor parent showed higher chlorophyll content than Hwaseong. To identify QTL associated with chlorophyll content, 58 $F_3$ and 38 $F_4$ lines were developed from a cross between HC-NIL and Hwaseong. For QTL analysis, simple sequence repeat (SSR) markers were used for genotyping and one-way ANOVA was conducted. A QTL for chlorophyll content (qCC2) was detected in chromosome 2 and explained 24.63% of phenotypic variation. The senescence effect of the qCC2 was examined in dark-induced incubation (DII). Detached leaves from Hwaseong and HC-NIL were incubated on 3mM MES buffer (pH 5.8) at $27^{\circ}C$ under complete dark condition. After 3 days of incubation, the Hwaseong leaves turned yellow, but the HC-NIL leaves were green. HC-NIL has higher chlorophyll content with delayed senescence than Hwaseong. These results indicated that qCC2 is associated with stay-green phenotype. To know whether the qCC2 is responsible for leaf functionality, ion leakage test and Fv/Fm measurement were performed. Both experiment results showed that differences were observed between Hwaseong and HC-NIL but it was not statistically significant. These results might suggest that the qCC2 is possibly related to chlorophyll content and non-functional stay-green phenotype.