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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Korean Journal of Microbiology
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The Microbiological Society of Korea
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Volume 48, Issue 4 - Dec 2012
Volume 48, Issue 3 - Sep 2012
Volume 48, Issue 2 - Jun 2012
Volume 48, Issue 1 - Mar 2012
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Bacterial Phosphate Homeostasis: Role of Phosphate Transporters
Park, Yoon-Mee ; Bang, Iel-Soo ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 57~65
DOI : 10.7845/kjm.2012.48.2.057
Phosphorous is an essential element for the synthesis of various biomolecules including phospholipids, carbohydrates and nucleic acids. Bacterial cells can uptake it as forms of phosphate and phosphate-containing nutrients from extracellular environments, and reserve extra phosphate to polyphosphate inside the cell. Among five phosphate transport systems, Pst plays central roles in phosphate transport, and its expression is coordinated by the regulation of PhoB-PhoR two component signal transduction system in response to extracellular levels of phosphate. Genomic studies on the response regulator PhoB reveal many genes independent of phosphate metabolism. Based on recent findings on phenotypes of bacteria lacking proper function of each phosphate transport system, this review discusses roles of phosphate transporters in maintaining optimum intracellular phosphate levels, and presents diverse phenotypes of phosphate transporters related with other environmental signals as well as phosphate, then finally points out functional redundancy among phosphate transport systems or their regulators, which emphasize importance of phosphate homeostasis in governing metabolism, adaptation, and virulence of bacteria.
Analysis of a Region Required for the Functions of Fission Yeast Nucleoporin Nup184 and Its SUMO Modification
Chai, Ai-Ree ; Jang, Soo-Yeon ; Yoon, Jin-Ho ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 66~72
DOI : 10.7845/kjm.2012.48.2.066
The Nup188 protein is one of the largest evolutionally conserved nucleoprins (Nups) that compose the inner ring of nuclear pore complex (NPC). The Nup184 protein, fission yeast Schizosaccharomyces pombe ortholog of Nup188p, is required for normal growth and mRNA export in nutrient-rich medium (YES). Here, we identified a carboxyl region (482 to 1628) of Nup184 protein that was enough to complement the defects of both growth and mRNA export when the
knock-out mutant was grown in YES medium. This region is also required for localization of GFP-Nup184 fusion to the nuclear periphery. In addition, we found that ORF of Nup184 (predicted 1564 amino-acid protein) registered in S. pombe GeneDB (hosted by Sanger Institute, UK) is 64 amino-acid residues shorter than that predicted by our sequence data. This carboxy-terminal region is necessary for the functions of Nup184p. We further demonstrated that Nup184 protein was conjugated with SUMO in vivo.
Enhancing the Enzymatic Activity of the Multifunctional β-Glycosyl Hydrolase (Cel44C-Man26A
) from Paenibacillus polymyxa GS01 Using DNA Shuffling
Kang, Young-Min ; Kang, Tae-Ho ; Yun, Han-Dae ; Cho, Kye-Man ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 73~78
DOI : 10.7845/kjm.2012.48.2.073
We previously reported that the truncated Cel44C-
-glycosyl hydrolase protein exhibits multifunctional activities, including cellulase, xylanase, and lichenase. DNA shuffling of the truncated Cel44C-
enzyme was performed to enhance the enzymatic activity of the multifunctional
-glycosyl hydrolase. Two mutant enzymes, M2Cel44C-
that carries one mutation (P438A) and M21Cel44C-
that carries two mutations (A273T and P438A) were obtained. The enzymatic activity of the M21Cel44C-
double mutant was lower than enzymatic activity of the single mutant (M2Cel44C-
). However, both mutants displayed the enhancements in their enzyme activities that were
- to 2.2-fold higher than the original enzymatic activity in Cel44C-
. In particular, the mutant M2Cel44C-
exhibited an approximate 1.5- to 2.2-fold increase in the cellulase, xylanase, and lichenase activities in comparison with the control (Cel44C-
). The optimum cellulase, linchenase, and xylanase activities of
-glycosyl hydrolase were observed at pH 7.0, pH 7.0 and pH 6.0, respectively. These results, therefore, suggest that the amino acid residue Ala438 plays important roles in the enhancement of the activity of multifunctional
Site-directed Mutagenesis Analysis Elucidates the Role of 223/227 Arginine in 23S rRNA Methylation, Which Is in 'Target Adenine Binding Loop' Region of ErmSF
Jin, Hyung-Jong ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 79~86
DOI : 10.7845/kjm.2012.48.2.079
ErmSF is one of the Erm family proteins which catalyze S-adenosyl-
-methionine dependent modification of a specific adenine residue (A2058, E. coli numbering) in bacterial 23S rRNA, thereby conferring resistance to clinically important macrolide, lincosamide and streptogramin B (
(ErmSF numbering) sequence appears to be a consensus sequence among the Erm family. This sequence was supposed to be involved in direct interaction with the target adenine from the structural studies of Erm protein ErmC'. But in DNA methyltarnsferase M. Taq I, this interaction have been identified biochemically and from the complex structure with substrate. Arginine 223 and 227 in this sequence are not conserved among Erm proteins, but because of the basic nature of residues, it was expected to interact with RNA substrates. Two amino acid residues were replaced with Ala by site-directed mutagenesis. Two mutant proteins still maintained its activity in vivo and resistant to the antibiotic erythromycin. Compared to the wild-type ErmSF, R223A and R227A proteins retained about 50% and 88% of activity in vitro, respectively. Even though those arginine residues are not essential in the catalytic step, with their positive charge they may play an important role for RNA binding.
Cellular Responses of Salmonella typhimurium Exposed to Green Tea Polyphenols
Choi, Hyo-Kyung ; Oh, Kye-Heon ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 87~92
DOI : 10.7845/kjm.2012.48.2.087
The purpose of this study was to examine the cellular response of Salmonella typhimurium exposed to tea polyphenols (TPP) extracted from Korean green tea (Camellia sinensis L.). TPP showed a dose-dependent bactericidal effect on S. typhimurium. Analysis of cell membrane fatty acids of S. typhimurium cultures treated with TPP identified unique changes in saturated and unsaturated fatty acids, while scanning electron microscopic analysis demonstrated the presence of perforations and irregular rod forms with wrinkled surfaces in cells treated with TPP. Two-dimensional polyacrylamide gel electrophoresis of soluble protein fractions from S. typhimurium cultures showed 16 protein spots increased by TPP. These up-regulated proteins including proteins involved in antioxidants and chaperons, transcript and binding proteins, energy and DNA metabolism were identified by peptide mass fingerprinting using MALDI-TOF. These results provide clues for understanding the mechanism of TPP induced stress and cytotoxicity on S. typhimurium.
Resistance Determinants and Antimicrobial Susceptibilities of Mupirocin-Resistant Staphylococci Isolated from a Korean Hospital
Min, Yu-Hong ; Lee, Jong-Seo ; Kwon, Ae-Ran ; Shim, Mi-Ja ; Choi, Eung-Chil ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 93~101
DOI : 10.7845/kjm.2012.48.2.093
We analyzed mupirocin resistance rates among staphylococcal isolates collected from a Korean hospital in 2003 (100 isolates), 2005 (195 isolates), 2006 (151 isolates), and 2009 (112 isolates). In Staphylococcus aureus, rates of high-level mupirocin resistance (MIC, minimal inhibitory concentration
) decreased and did not appear since 2005. In contrast, low-level mupirocin resistance (MIC
) was not detected in 2003 and 2005 but its rates later increased to 6.9% in 2009. Total resistance rates of coagulase-negative staphylococci (CNS) were significantly higher than those of S. aureus. The rates of high-level resistance of CNS increased from 16.0% in 2003 to 31.5% in 2009. The rate of low-level resistance of CNS was 8.0% in 2003 and around 11% later. In all high-level resistant isolates, the ileS-2 gene was detected. All low-level resistant isolates contained the known V588F mutation in ileS gene. Previously unknown mutations such as V458G in S. aureus and D172A, Y490H and I750V in CNS were identified additionally. One S. aureus isolate with high-level resistance was resistant to oxacillin and several topical antibiotics commonly used for the treatment of skin infection. Ten S. aureus isolates with low-level resistance were also resistant to all of these antibiotics except fusidic acid. CNS isolates with high-level (61 isolates) and low-level resistance (27 isolates) exhibited significantly higher resistance rates to these antibiotics than mupirocin-susceptible CNS isolates (167 isolates). In conclusion, prevention of the emergence of mupirocin resistance is necessary for the effective treatment of skin infection by staphylococci.
Prevalence of Human Noroviruses Detected from Outbreaks of Gastroenteritis Patients in Seoul, Korea
Kim, Eun-Jeung ; Kim, Moo-Sang ; Chae, Young-Zoo ; Cheon, Doo-Sung ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 102~108
DOI : 10.7845/kjm.2012.48.2.102
Fecal specimens from acute gastroenteritis in Seoul from 2003 to 2007 were collected and then tested for the presence of Norovirus by RT-PCR. Among a total of 4,685 samples investigated, 383 samples (8.2%) were positive. The analysis of outbreaks related norovirus contamination occurred from 2003 to 2007 in Seoul revealed 57 cases happened during investigated period. Seasonal prevalence showed winter season predominant characteristics of pattern of epidemics by long term investigation for norovirus infections. The incidence of norovirus infection in the case of acute gastroenteritis by catering food in school were 32%, by food in general restaurant were 29%. This epidemiological investigation in Seoul was strongly needed for control and prevention of outbreaks related with norovirus by forecasting disease epidemics.
Effect of Recombinant CagL Immunization on the Gastric Diseases Induced by Helicobacter pylori in Mongolian gerbils
Bak, Eun-Jung ; Jang, Sung-Il ; Choi, Yun-Hui ; Kim, Jin-Moon ; Kim, Ae-Ryun ; Kim, Ji-Hye ; Woo, Gye-Hyeong ; Yoo, Yun-Jung ; Lee, Sung-Haeng ; Cha, Jeong-Heon ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 109~115
DOI : 10.7845/kjm.2012.48.2.109
Helicobacter pylori is an important factor of chronic gastritis, digestive ulcer, and stomach cancer. CagL, a virulence factor of H. pylori, is well-known as a pilus protein which acts as adhesion to host cell and a component of Type 4 secretion system. In this study, we evaluated the protective response of recombinant CagL protein (rCagL) using Mongolian gerbil animal model for H. pylori infection. The cagL gene was cloned from 26695 H. pylori followed by over-expression and purification of the protein in E. coli. Mongolian gerbils were immunized with rCagL protein mixed with aluminum adjuvant via intramuscular injections once a week during 4 weeks. At a week after the last immunization, the Mongolian gerbils were administrated with H. pylori 7.13 strain into the stomach and sacrificed to measure antibody titer on rCagL by ELISA and bacterial colonization in the stomach, and to examine the histopathological changes and cytokine expression at 6 week after challenge. Antibody titers on recombinant protein were significantly increased from a week after the first immunization. There was no significant change of the number of bacterial colony between control group and immunized group. The relative stomach weight was significantly decreased in immunized group, but the significant change of histopathological assessment was not observed in the stomach. Cytokine expression such as IL-
and KC also was not significantly different between control and immunized groups. These results indicate that rCagL could effectively induce the formation of the specific IgG antibodies. However, bacterial colonization and histopathological lesions could not be inhibited by the immunization in the stomach, indicating not enough protection against H. pylori infection. We consider that along with CagL other adequate antigens could be needed stimulating immune response and inducing protective effects against gastric disease, and also a better adjuvant could be considered.
Antibiotics Resistance and Molecular Analysis of Enterococcus Isolated from the Han-river in Korea
Kwon, Oh-Min ; Kim, Mal-Nam ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 116~124
DOI : 10.7845/kjm.2012.48.2.116
Identification was performed in March 2008 for the 76 Enterococcus strains isolated from the Han-river, which is used as water supply for Seoul citizens. The antibiotic susceptibility, antibiotic resistant structural analysis, trans-conjugation, pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were also carried out for the isolated strains. Among the isolated strains, 25 strains were E. casseliflavus, 4 strains were E. faecalis and 1 strain was E. hirae. Investigation of antibiotic susceptibility indicated that 15 strains demonstrated tolerance against vancomycin, and that 11 strains of E. faecium and 4 strains of E. casseliflavus were VRE. The vanA gene detection of the VRE strains revealed that 6 E. faecium strains were vancomycin-resistant Enterococcus faecium (VREF) possessing vanA. Analyses of transposon Tn1546 structure containing vanA demonstrated that Km36 and Km37 belonged to Tn1 type, Km20 and Km38 was Tn2 type, and Km39 and Km40 was Tn3 type. PFGE disclosed that among the 6 VREF strains, Km36 and Km37 exhibited equivalent subtype, while the rest 4 strains showed subtypes different to each other. MLST for the 6 VREF strains disclosed that 3 strains were ST78, while the rest 3 strains were ST18, ST192 and ST230, respectively. All these clonal complexes were derived from CC17 which has been isolated from clinical sources. 4 strains belonged to CC78, while the rest 2 strains were CC18 and CC192, respectively.
Microbial Diversity in Three-Stage Methane Production Process Using Food Waste
Nam, Ji-Hyun ; Kim, Si-Wouk ; Lee, Dong-Hun ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 125~133
DOI : 10.7845/kjm.2012.48.2.125
Anaerobic digestion is an alternative method to digest food wastes and to produce methane that can be used as a renewable energy source. We investigated bacterial and archaeal community structures in a three-stage methane production process using food wastes with concomitant wastewater treatment. The three-stage methane process is composed of semianaerobic hydrolysis/acidogenic, anaerobic acidogenic, and strictly anaerobic methane production steps in which food wastes are converted methane and carbon dioxide. The microbial diversity was determined by the nucleotide sequences of 16S rRNA gene library and quantitative real-time PCR. The major eubacterial population of the three-stage methane process was belonging to VFA-oxidizing bacteria. The archaeal community consisted mainly of two species of hydrogenotrophic methanogen (Methanoculleus). Family Picrophilaceae (Order Thermoplasmatales) was also observed as a minor population. The predominance of hydrogenotrophic methanogen suggests that the main degradation pathway of this process is different from the classical methane production systems that have the pathway based on acetogenesis. The domination of hydrogenotrophic methanogen (Methanoculleus) may be caused by mesophilic digestion, neutral pH, high concentration of ammonia, short HRT, and interaction with VFA-oxidizing bacteria (Tepidanaerobacter etc.).
Distribution and Characteristics of Microorganisms Associated with Settled Particles During Asian Dust Events
Koh, Ji-Yun ; Jang, Chan-Gook ; Cha, Min-Ju ; Park, Kyo-Nam ; Kim, Min-Kyu ; Kim, Jong-Seol ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 134~140
DOI : 10.7845/kjm.2012.48.2.134
Asian dust storms originating in the arid desert of China and Mongolia usually occur from late winter through spring, and more than one million tons of dust per year is transported to the Korean Peninsula by the prevalent westerly winds. We supposed that these dust particles could include bioaerosols and act as carriers of microorganisms. In order to clarify the dynamics of microorganisms moving with these particles, the concentration and composition of microorganisms associated with settled particles were compared between samples collected during Asian dust events and those under non-dust periods. From February to April 2008, settled dust particles were collected at one location in Ulsan using rainfall meter of 200 mm diameter. During this period, there was one Asian dust event in Ulsan. The bacterial concentrations were higher in samples collected during Asian dust event than those under non-dust period, whereas fungal concentrations were rather similar regardless of the Asian dust event. We analyzed 16S rRNA gene sequences of 45 bacterial isolates obtained from the settled particle samples. These isolates belonged to either genus Bacillus or genus Streptococcus and were tentatively identified as B. amyloliquefaciens, B. aryabhattai, B. atrophaeus, B. licheniformis, B. megaterium, B. methylotrophicus, B. pumilus, B. sonorensis, B. subtlis, B. vallismortis, S. epidermidis, and S. succinus. In cases of fungal isolates, genera such as Mucor, Alternaria, Cladosporium, and Aspergillus were tentatively identified from samples collected at both Asian dust and non-Asian dust periods. It appears that endospore-forming bacteria such as Bacillus sp. rather than fungal spores are more likely to be associated with Asian dust particles.
Cloning and Characterization of Xylanase Gene from Paenibacillus woosongensis
Yoon, Ki-Hong ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 141~146
DOI : 10.7845/kjm.2012.48.2.141
A gene encoding the xylanase (XynA) predicted from partial genomic sequence of Paenibacillus woosongensis was cloned into Escherichia coli by PCR. This xynA gene consisted of 633 nucleotides, encoding a polypeptide of 211 amino acid residues. The deduced amino acid sequence exhibited 85-89% identity with those of several Paenibacillus xylanases, belonging to the glycosyl hydrolase family 11. As a results of expression of the structural gene by T7 promoter of a pET23a(+) expression vector, xylanase activity was higher in cell-free extract than culture filtrate of a recombinant Escherichia coli BL21(DE3) CodonPlus. However, the expression level of xylanase was not sufficient be detected by SDS-PAGE. The cell-free extract showed maximal xylanase activity at
and pH 5.5. The predominant products resulting from xylan and xylooligosaccharide hydrolysis were xylose and xylotriose. The enzyme could hydrolyze xylooligosaccharides larger than xylbiose.
Quality Characteristics of Wheat-Rice Makgeolli by Making of Rice Nuruk Prepared by Rhizopus oryzae CCS01
Seo, Weon-Taek ; Cho, Hyeon-Kook ; Lee, Ju-Young ; Kim, Baolo ; Cho, Kye-Man ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 147~155
DOI : 10.7845/kjm.2012.48.2.147
To improve of the quality of Korea traditional wheat-rice wine (makgeolli) production, we used a rice fermentation starter (rice nuruk) made by inoculation of Rhizopus oryzae CCS01 which was isolated and selected from commercial nuruk. Amylase activity of a rice nuruk was 1.8-2.4 times higher than those of commercial nuruks. The best acceptability of wheat-rice wine in a sensory test was observed at 4 : 6 ratio of wheat-rice mash at experimental condition. During the fermentation period, pH of wheat-rice makgeolli made with a rice nuruk was higher compared to those made with commercial nuruks such as Sanseong, Jinju, and Songhak. Acidity of makgeolli mash was lower in case of using a rice nuruk and birx and alcohol production were higher compared to those of makgeolli mash using commercial nuruks. Highest alcohol production was observed at makgeolli mash using a rice nuruk and 12% of alcohol was produced at fermentation end. These results suggest that production of a new type of wheat-rice makgeolli using a rice nuruk was possible.
Enzymatic Characterization of Salmonella typhimurium Mannitol Dehydrogenase Expressed in Escherichia coli
Jang, Myoung-Uoon ; Park, Jung-Mi ; Kim, Min-Jeong ; Kang, Jung-Hyun ; Lee, So-Won ; Kim, Tae-Jip ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 156~162
DOI : 10.7845/kjm.2012.48.2.156
A mannitol dehydrogenase (StMDH) gene was cloned from Salmonella typhimurium LT2 (KCTC 2421) and overexpressed in Escherichia coli. It has a 1,467 bp open reading frame encoding 488 amino acids with deduced molecular mass of 54 kDa, which shares approximately 36% of amino acid identity with known long-chain dehydrogenase/reductatse (LDR) family enzymes. The recombinant StMDH showed the highest activity at
, and pH 5.0 and 10.0 for D-fructose reduction and D-mannitol oxidation, respectively. On the contrary, it has no activity on glucose, galactose, xylose, and arabinose. StMDH can catalyze the oxidative/reductive reactions between D-fructose and D-mannitol only in the presence of
/NADH as coenzymes. These results indicate that StMDH is a typical
/NADH-dependent mannitol dehydrogenase (E.C. 220.127.116.11).
Antimicrobial and Biogenic Amine-Degrading Activity of Bacillus licheniformis SCK B11 Isolated from Traditionally Fermented Red Pepper Paste
Kim, Yong-Sang ; Jeong, Jin-Oh ; Cho, Sung-Ho ; Jeong, Do-Yeon ; Uhm, Tai-Boong ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 163~170
DOI : 10.7845/kjm.2012.48.2.163
In order to inhibit the growth of pathogens and degrade biogenic amines during the fermentation of soybean products, an isolate with antimicrobial activity against pathogens and biogenic amine-degrading property was obtained from 83 traditionally fermented soybean products. The morphological and biochemical tests and the phylogenetic relationship among 16S rRNA gene sequences indicated that the isolate named as the strain SCK B11 was most closely related to Bacillus licheniformis. The cell-free supernatant of two day cultures was active against several pathogens including Enterococcus faecalis, Listeria monocytosis, Micrococcus luteus, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus. PCR analysis was conducted to determine relatedness to antimicrobial lantibiotics and biosurfactants produced by Bacillus spp., but showed negative for the genes encoding surfactin, lichenysin, and lichenicidine. Electron microscopic observation indicated that the antimicrobial agent seemed to attack the membrane of the pathogens, leaving the ghost or shrunken cells. The strain was found to degrade histamine by 72% and tyramine by 66% in the cooked soybean containing 5.3% of biogenic amine over 10 days of fermentation time. The use of selected strain would be a potential control measure in manufacturing traditionally fermented soybean products that are difficult to control pathogens and biogenic amine levels.
Effects of the Repression of sphpr1 Expression on Growth and mRNA Export in Fission Yeast
Lee, Hyun-Joo ; Yoon, Jin-Ho ;
The Korean Journal of Microbiology, volume 48, issue 2, 2012, Pages 171~174
DOI : 10.7845/kjm.2012.48.2.171
THOC1/Hpr1 is one subunit of THO complex that is an evolutionally conserved assembly involved in the mRNP packaging and mRNA export during transcription elongation. In fission yeast Schizosaccharomyces pombe, an ortholog (spHpr1) of THOC1/Hpr1 was identified based on sequence alignment. A deletion mutant in a diploid strain was constructed by replacing one of spHpr1-coding region with a
gene using one-step gene disruption method. Tetrad analysis showed that the sphpr1 is essential for growth. Over-expression of sphpr1 from strong nmt1 promoter caused no defects of growth and mRNA export. However, repression of the sphpr1 expression resulted in growth inhibition accompanied by accumulation of poly
RNA in the nucleus. These results suggest that spHpr1 is involved in mRNA export from the nucleus to cytoplasm.