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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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Journal DOI :
The Microbiological Society of Korea
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Volume & Issues
Volume 50, Issue 4 - Dec 2014
Volume 50, Issue 3 - Sep 2014
Volume 50, Issue 2 - Jun 2014
Volume 50, Issue 1 - Mar 2014
Selecting the target year
Antimicrobial Mechanisms of Nitric Oxide and Strategies for Developing Nitric Oxide-based Antimicrobial Agents
Choi, Eun Young ; Noh, Jin-Ki ; Hasan, Nurhasni ; Yoo, Jin-Wook ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 87~94
DOI : 10.7845/kjm.2014.4029
Nitric oxide (NO), which has been recognized as an integral molecule in maintaining homeostasis, plays an important role in host defense against microbes. NO has diverse antimicrobial mechanisms by directly and/or indirectly interacting with microbes. Under the circumstance that there is an urgent need for a new class of antimicrobial agents due to antibiotic resistance, much effort has been made to develop a NO-based antimicrobial agent. In order to make it possible, strategies to store and release NO in a controlled manner are required because NO has a gaseous property and a very short half-life. In this review, we described NO biochemistry and its mechanisms of antimicrobial activity. In additions, we introduced various NO-releasing systems that improve NO`s antimicrobial activity.
Characterization of Hrq1-Rad14 Interaction in Saccharomyces cerevisiae
Min, Moon-Hee ; Kim, Min-Ji ; Choi, You-Jin ; You, Min-Ju ; Kim, Uy-Ra ; An, Hyo-Bin ; Kim, Chae-Hyun ; Kwon, Chae-Yeon ; Bae, Sung-Ho ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 95~100
DOI : 10.7845/kjm.2014.4016
Hrq1 is a novel member of RecQ helicase family, found in fungal genomes by bioinformatics analyses. It is most homologous to human RECQL4 and recent genetic and biochemical studies suggested that it may play roles in the maintenance of genome stability. In this study, we investigated yeast two-hybrid interactions between Hrq1 and the yeast genes homologous to the human genes that are known to interact with RECQL4. Among the 11 genes tested, Rad14, a nucleotide excision repair (NER) factor, was found to interact with Hrq1. In addition, pull-down assay with the purified proteins revealed direct protein-protein interaction between Hrq1 and Rad14. The yeast two-hybrid interaction was enhanced by the DNA damage induced by 4-nitroquinoline-1-oxide, which was dependent on the presence of Rad4, a key NER factor. These results suggest that Hrq1 may function in NER through interaction with Rad14.
Bacterial Contamination and Antimicrobial Resistance of the Surrounding Environment Influencing Health
Lee, Do Kyung ; Park, Jae Eun ; Kim, Kyung Tae ; Jang, Dai Ho ; Song, Young Cheon ; Ha, Nam Joo ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 101~107
DOI : 10.7845/kjm.2014.4019
Community-acquired antimicrobial resistant bacteria are an emerging problem world-wide. In Korea, resistant bacteria are more prevalent than in other industrialized countries. The aim of this study was to investigate the isolation frequency of methicillin-resistant staphylococci (MRS), Pseudomonas, and Enterobacteriaceae from surrounding environment (home, colleges, public transportation system and possessions) in Seoul, and to examine the level of drug resistance to 13 antimicrobial agents, which are in wide spread clinical use in Korea, as well as new agent, tigecycline in Enterobacteriaceae isolates. Of total 239 samples, 18 (7.5%) MRS, 10 (4.2%) Pseudomonas, and 30 (12.6%) Entarobacteriaceae were isolated. A total of 5 (2.1%) methicillin-resistant S. aureus (MRSA) were detected in home (2 samples), colleges (1 sample), and et cetera (2 sample). A total of 5 (2.1%) Escherichia coli were detected in in home (1 samples), public transportations (3 sample), and et cetera (1 sample). Resistance to cephalosporins, fluoroquinolones, carbapenems,
-lactams, tetracyclines, and aminoglycosides was found in 71.9%, 71.9%, 68.8%, 68.8%, 50.0%, and 25.0% of 32 Enterobacteriaceae isolates, respectively. Also, resistance rate to trimethoprim/sulfamethoxazole of the isolates was a 43.8%. Moreover, 59.4% of the isolates were resistant to new agent, tigecycline and resistance to all agents tested was observed in 3 isolates. Five E. coli isolates were resistant to most of the agents tested, but some of them were susceptible to ciprofloxacin and gentamicin. This study can serve as a data point for future comparisons of possible changes in antibiotic resistance levels in surrounding environment. And multilateral strategies for preventing the incidence and spread of antibiotic resistance are needed.
Time-course Analysis of Biofilm Formation in Quorum Sensing-deficient Bacteria
Kim, Soo-Kyoung ; Lee, Mi-Nan ; Lee, Joon-Hee ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 108~113
DOI : 10.7845/kjm.2014.4028
Pseudomonas aeruginosa and Vibrio vulnificus are Gram-negative human pathogens, which exert their virulence through quorum sensing (QS) regulation. The infection of these pathogens have been known to be mediated by biofilm formation in many cases and this study carried out the time-course analysis of biofilm formation depending on the QS regulation in P. aeruginosa and V. vulnificus. In P. aeruginosa, our results demonstrated that QS-deficient mutant better attached to surface at initial stage of biofilm formation, but poorly proceeded to the maturation of the biofilm structure, while wild type less attached at initial stage but developed highly structured biofilm at late stage. Because of this, the quantitative comparison of biofilm formation between wild type and the QS mutant showed the reversion; the QS mutant formed more biofilm until 10 h after inoculation than wild type, but wild type formed much more biofilm after 10 h than QS mutant. V. vulnificus has been reported to form more biofilm with the mutation on QS system. When we performed the same time-course analysis of the V. vulnificus biofilm formation, the reversion was not detected even with prolonged culture for 108 h and the QS mutant always forms more biofilm than wild type. These results indicate that the QS regulation negatively affects the attachment at early stage but positively facilitates the biofilm maturation at late stage in P. aeruginosa, while the QS regulation has a negative effect on the biofilm formation throughout the biofilm development in V. vulnificus. Based on our results, we suggest that the developmental stage of biofilm and bacterial species should be considered when the QS system is targeted for biofilm control.
bla Genotype and Molecular Epidemiological Analysis of Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae in Chungcheong Regional Hospitals
Yook, Keun Dol ; Yang, Byoung Seon ; Park, Jin Sook ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 114~118
DOI : 10.7845/kjm.2014.4032
A total of 122 ESBL-producing intestinal bacteria were collected from regional hospitals in the Chungcheong area. Combination disk test (CDT) was performed for antimaicrobial susceptability using cefotaxime and cefotaxime/clavulanate according to Clinical Laboratory Standard Institute (CLSI). Mutiplex PCR using specific primers was performed for a detection of ESBL-genotypes and enterobacterial repetitive intergenic consensus (ERIC)-PCR was carried out for the tracking of molecular epidemiology. In the confirmation test using CDT, 73 out of 76 (96.1%) ESBL-producing Escherichia coli and 43 out of 46 (93.4%) ESBL-producing Klebsiella pnemoniae were positive. In the multiplex PCR, 60.5% of E. coil were positive for CTX-M-2 type gene and 56.5% of K. pneumoniae were positive for VEB -1 type gene. In the ERIC-PCR, E. coil isolates formed 5 clusters and K. pneumoniae isolates were grouped into 4 clusters depending on region. Genotypes of clinical isolates are useful for detection and differentiation of ESBL producing intestinal bacteria. The ERIC-PCR method is thought to be helpful for establishing a regional surveillance system for infection due to its formation of different clusters depending on region.
Diversity and Physiological Characteristics of Culturable Bacteria from Marine Sediments of Ross Sea, Antarctica
Lee, Yung Mi ; Jung, You-Jung ; Hong, Soon Gyu ; Kim, Ji Hee ; Lee, Hong Kum ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 119~127
DOI : 10.7845/kjm.2014.4014
The affiliations and physiological characteristics of culturable bacteria isolated from the sediments of Ross Sea, Antarctica were investigated. Sixty-three isolates obtained by cultivation were grouped into 21 phylotypes affiliated with the phyla Actinobacteria and Bacteroidetes and with the classes Alphaproteobacteria and Gammaproteobacteria by phylogenetic analysis of 16S rRNA gene sequences. Based on phylogenetic analysis (<98.65% sequence similarity), approximately 49% of total isolates represented potentially novel species or genus. Among them, extracellular protease, lipase, and exopolysaccharide activities at
were detected in approximately 46%, 25%, and 32% of the strains, respectively. Forty-three isolates produced at least one type of extracellular material and 21 of them produced at least two extracellular protease, lipase, and/or exopolysaccharides. Our findings indicate that culturable bacterial diversity present within the marine sediments of Ross Sea, Antarctica may contribute to the hydrolysis of the major organic constituents which is closely related with carbon and nitrogen cycling in this environment.
Characterization of Quorum-Quenching Bacteria Isolated from Biofouled Membrane Used in Reverse Osmosis Process
Moon, Sooyoung ; Huang, Xinxin ; Choi, Sung-Chan ; Oh, Young-Sook ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 128~136
DOI : 10.7845/kjm.2014.4017
Acyl homoserine lactone (AHL) lactonase has been proved to be the AHL-degrading enzyme with the highest substrate specificity for AHL molecules and has shown a considerable potential as low-cost and efficient quorum quenching (QQ) technique. However, few studies focused on its inhibitory effect on biofilm formation which is also a quorum sensing (QS)-regulated phenomenon. In this study, QQ activity of six isolates from biofouled reverse osmosis membranes was studied using Chromobacterium violaceum CV026 and Agrobacterium tumefaciens NTL4 as biosensors under various conditions. All of the isolates belonged to the genus Bacillus and showed QQ activity regardless of the acyl chain length or substitution of AHL molecule. The isolates were capable of significantly inhibiting biofilm formation (46.7-58.3%) by Pseudomonas aeruginosa PAO1 and produced heat-sensitive extracellular QQ substances. The LC-MS analysis of the QQ activity of a selected isolate, RO1S-5, revealed the degradation of N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12 AHL) and the production of corresponding acyl homoserine (3-oxo-C12-HS), which indicated the activity of AHL lactonase. The broad AHL substrate range and high substrate specificity suggested that the isolate would be useful for the control of biofilm-related pathogenesis and biofouling in industrial processes.
Denitrification Potential and Denitrifier Abundance in Downstream of Dams in Temperate Streams
Vo, Nguyen Xuan Que ; Lee, Seung-Hoon ; Doan, Tuan Van ; Jung, Sokhee P. ; Kang, Hojeong ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 137~151
DOI : 10.7845/kjm.2014.4021
Various studies have been conducted to investigate effects of dams on river ecosystems, but less information is available regarding damming impacts on downstream denitrification. We measured denitrification enzyme activity (potential denitrification rate) and denitrifier abundances (using nirS, nirK, and nosZ as markers) in dammed headstreams of the Nakdong River in South Korea. Sediments in Phragmites-dominated riparian areas and in-stream areas across streams (dammed vs. reference) with different streambed materials (gravel and sand) were sampled occasionally. We hypothesized that (i) the higher available N and C contents in sediments downstream of dams foster larger denitrifier communities than in the reference system and (ii) differences in potential denitrification rates across the systems correspond with denitrifier abundances. Despite 30 years of different hydrological management with dams and greater inorganic N and DOC contents in sediments downstream of dams, compared to the references, abundances of denitrifier communities and potential denitrification rates within the whole sediment were not significantly different across the systems. However, nirS and nosZ denitrifier abundances and potential denitrification rates were considerably increased in specific sediments downstream of dams (gravelly riparian and sandy in-stream) with regard to flooding events and seasonal temperature variation. nirK was not amplified in all sediments. Canonical correspondence analyses (CCA) revealed that the relationship between abundances of denitrifier communities and nutrient availabilities and potential denitrification rates was a weak one.
Phylogenetic Diversity of Bacterial Community Inhabited in Callyspongia elegans
Park, So-Hyun ; Kim, Ji-Young ; Kim, Young-Ju ; Heo, Moon-Soo ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 152~157
DOI : 10.7845/kjm.2014.4030
The aim of this study was to investigate the bacterial community inhabited in Callyspongia elegans. Marine bacteria were isolated from the marine sponge C. elegans using marine agar. The resulting 112 isolated pure cultures were then used for further study. They were characterized by determining morphological characteristics through Gram`s staining and morphological observation. The colony pigments of bacterial isolates were characterized as yellow, brown, ivory, and white. Thirty-seven strains were found to be Gram-positive and 75 strains were Gram-negative. Seventy-nine strains were coccus-shaped, while 16 strains were rod-shaped. On the basis of the results of the comparative analyses of 16S rDNA gene sequences, the 112 isolated bacteria were divided into 5 major groups: Alphaproteobacteria (39%), Gammaproteobacteria (22%), Actinobacteria (14%), Fimicutes (9%), and Bacteroidetes (6%). It is strongly suggested that fifteen isolates are candidates for a new genera or species, based on the analyses of 16S rDNA gene sequences.
Production and Properties of Mannanase by a Bacillus amyloliquefaciens Isolate
Yoon, Ki-Hong ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 158~163
DOI : 10.7845/kjm.2014.4015
In the acidic LB plate, a bacterial strain was isolated from homemade soybean paste as a producer of the extracellular mannanase. The isolate YB-1402, which was a Gram-positive rod-shaped bacterium with spore, has been identified as Bacillus amyloliquefaciens on the basis of its 16S rDNA sequence and biochemical properties. Maximum mannanase productivity of the isolate YB-1402 was reached approximately 150 U/ml in LB broth supplemented with konjac (3.0%). The molecular mass of YB-1402 mannanase was estimated to approximately 38.0 kDa by zymogram of the culture filtrate on SDS-PAGE. The mannanase of culture filtrate was the most active at
and pH 5.5. The mannanase activity was completely maintained after pre-incubation at pH 3.0 to 10.0 for 1 h. The predominant products resulting from the mannanase hydrolysis were mannose, mannobiose and mannotriose for LBG or mannooligosaccharides. The enzyme could hydrolyze mannooligosaccharides larger than mannobiose.
Diversity Analysis for Archaeal amoA Gene in Marine Sediment of Svalbard, Arctic Circle
Park, Soo-Je ; Rhee, Sung-Keun ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 164~168
DOI : 10.7845/kjm.2014.4023
The ecosystem of the Arctic region has been increasingly affected by global warming. Archaeal ammonia monooxygenase alpha subunit coding gene (amoA) which is a key enzyme for nitrification was used to investigate the effect of runoff water of ice melt on microbial community of nitrogen cycle. The archaeal amoA genes at coastal area of Svalbard, Arctic region were PCR-amplified and sequenced after clone library construction. Analysis of archaeal amoA gene clone libraries suggested that the station 188 which is in the vicinity to the area of runoff water harbor lower ammonia-oxidizing archaeal diversity than the station 176 and 184. The average amino acid sequence identity within all archaeal amoA gene clones was 94% (with 91% nucleotide sequence identity). While all the clones of the station 188 were affiliated with Nitrosoarchaeaum clade containing strains isolated from low-salinity and terrestrial environments, about 45% of total clones of the station 176 and 184 were related to marine Nitosopumilus clade. Interestingly, other typical archaeal amoA gene clones of thaumarchaeal I.1b clade frequently retrieved from terrestrial environments was identified at station 188. Microbial community of nitrogen cycle in marine sediment might be affected by input of sediments caused by runoff glacier melt waters.
The Interaction between HCV-Infected huh7.5 Cells and HCV-Specific T Cells
Kang, Hyojeung ; Cho, Hyosun ;
The Korean Journal of Microbiology, volume 50, issue 2, 2014, Pages 169~172
DOI : 10.7845/kjm.2014.4020
Recently, Hepatitis C virus (HCV) replication system has been established using human hepatoma cells (huh cell) and a variety of HCV clones. In this study, we established an infectious HCV replication system using huh7.5 cells and J6/JFH1 clone (genotype 2a). In addition, we investigated the antigen presentation capability of HCV-infected huh7.5 cells to HCV-specific T cells. Interestingly, HCV-infected huh7.5 cells were not capable of activating HCV-specific T cells. However, huh7.5 cells stimulated by exogenous HCV peptide were able to activate HCV-specific T cells, which was shown to produce TNF-
. We further examined if HCV infection has an inhibitory effect on the expression of MHC class I molecule of huh7.5 cells. We found that HCV infection did not change the expression level of MHC class I molecule on huh7.5 cells.