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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 46, Issue 4 - Dec 2010
Volume 46, Issue 3 - Sep 2010
Volume 46, Issue 2 - Jun 2010
Volume 46, Issue 1 - Mar 2010
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Studies on the Functional Role of RNase G in the Regulation of Escherichia coli Enolase Expression Under Microaerobic Conditions
Sim, Se-Hoon ; Kim, Yong-Hak ; Sim, Min-Ji ; Lim, Bo-Ram ; Lee, Kang-Seok ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 229~232
Enolase is one of the glycolytic enzymes, which are involved in a central energy metabolism present in nearly all organisms. In Escherichia coli, enolase constitutes RNA degradosome with RNase E, PNPase and RNA helicase, which are involved in most mRNA degradation and RNA processing. Recently, it has been reported that RNase G, an RNase E homolog, degrades eno mRNA. To examine a functional role of RNase G in enolase expression which is known to be up-regulated under microaerobic condition, we carried out experiments. Here, we report that expression levels of enolase and RNase G are not correlated under microaerobic condition. Based on this observation, we suggest the existence of an unknown factor(s) which regulate the activity of RNase G or enolase mRNA under microaerobic conditions.
Cold-Sensitive Growth of Bacillus subtilis Mutants Deleted for Putative DEAD-Box RNA Helicase Genes
Oh, Eun-Ha ; Lee, Sang-Soo ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 233~239
Four genes (yqfR, yfmL, ydbR, deaD) were identified as putative DEAD-box RNA helicase genes in the genomic sequence of Bacillus subtilis by homology search. To understand the function of these genes, each of the genes was deleted and the constructed strains were tested for their growth charateristics at different temperatures. The growth rate of ydbR deletion mutant (
=53 min) was a little bit reduced at
as compared to that of wild type strain (CU1065). But the growth rate of other three (yqfR, yfmL, deaD) deletion mutants (
=30-40 min) is nearly equal to the growth rate of wild type (
=32 min). On the other hands, the growth rate of deletion mutants were reduced at
in order of yqfR (
=151 min), yfmL (
=214 min), ydbR (
=343 min), which showed cold-sensitive phenotype. The deletion mutant of deaD (
=109 min) grew equally as compared to the growth rate (
=102 min) of the wild type at
and did not show cold-sensitive growth. Double, triple and quadruple deletion mutants of these genes were constructed, and growth rate of these mutants were measured at various temperature conditions (
) using LB broth. Multiple deletion mutations showed more severe cold-sensitive growth than single deletion mutations, and double deletion of ydbR and yfmL (
=984 min) showed most cold-sensitive growth than any other double mutants. Such a cold-sensitive growth of these mutations is quite similar to the result of csdA or srmB deletion in E. coli and suggested that physiological role of ydbR and yfmL is related with ribosome assembly.
Analysis of Quorum Sensing-Related Phenotypes of Pseudomonas aeruginosa Clinical Isolates
Jung, Kyung-Ju ; Choi, Yu-Sang ; Ha, Chang-Wan ; Shin, Jeong-Hwan ; Lee, Joon-Hee ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 240~247
Pseudomonas aeruginosa is a Gram (-) opportunistic human pathogen causing a wide variety of infections on lung, urinary tract, eyes, and burn wound sites and quorum sensing (QS), a cell density-sensing mechanism plays an essential role in Pseudomonas pathogenesis. In order to investigate the importance of QS in the Pseudomonas infections of Korean patients, we isolated 189 clinical strains of P. aeruginosa from the patients in Pusan Paik Hospital, Busan, South Korea. The QS signal production of these clinical isolates was measured by signal diffusion assay on solid media using reporter strains. While most clinical strains (79.4%) produced the QS signals as similar level as a wild type strain, PAO1 did, where LasR, the initial QS signal sensor-regulator was fully activated, a minority of them (4.2%) produced much less QS signals at the level to which LasR failed to respond. Similarly, while 72.5% of the clinical isolates produced QS signals enough to activate QscR, an another QS signal sensor-regulator, some few of them (9%) produced the QS signals at much lower level where QscR was not activated. For further analysis, we selected 74 clinical strains that were obtained from the patients under suspicion of Pseudomonas infection and investigated the total protease activity that is considered important for virulence. Interestingly, significant portion of them showed very low protease activity (44.6%) or no detectable protease activity (12.2%). When the biofilm-forming ability that is considered very important in chronic infection was examined, most isolates showed lower biofilm-forming activity than PAO1. Similarly, significant portion of clinical isolates showed reduced motility (reduced swarming activity in 51.4% and reduced twitching activity in 41.9%), or non-detectable motility (swarming-negative in 28.4% and twitching-negative in 28.4%). Our result showed that the clinical isolates that produced QS signals at the similar level to wild type could have significantly reduced activities in the protease production, biofilm formation, and motility, and some clinical isolates had unique patterns of motility, biofilm formation, and protease production that are not correlated to their QS activity.
Antifungal Activities of Pseudomonas spp. Strains Against Plant Pathogens and Optimization of Culture Conditions
Chang, Seog-Won ; Choi, Byung-Jin ; Hong, Jeum-Kyu ; Rho, Yong-Taek ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 248~254
To define the optimum conditions for the mass production of four antifungal Pseudomonas spp. isolated from soil, we have investigated culture conditions and effects of various nutrient sources on the bacterial growth and evaluated antagonistic activity against Rhizoctonia solani and Sclerotinia homoeocarpa, plant pathogens. The optimum temperature and pH for the growth of these isolates were determined as pH 7.0 and
, respectively. Sucrose, tryptone, and
generally were more adequate for better growth as carbon, nitrogen and mineral source, respectively. The nutrient sources were also found to be very effective for high antifungal activities against R. solani and S. homoeocarpa. It was elucidated that YUD-F group (P. mandelii and P. fluorescens), which inhabit regions at relatively low temperature, had more broad spectrum and higher antifungal activity than YUD-O group (P. trivialis and P. jessenii) generally against R. solani and S. homoeocarpa. It is thought that the differences of the average temperature in the various habitats of Pseudomonas spp. influence the optimal growth temperature and antifungal activity. Especially, Pseudomonas spp. of YUD-O group showed the better antifungal activity against dollar spot caused by S. homoeocarpa, but showed relatively weaker antifungal activity against brown patch caused by R. solani.
Bacterial Community Diversity Associated with Two Marine Sponges from the South Pacific Ocean based on 16S rDNA-DGGE analysis
Park, Jin-Sook ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 255~261
The bacterial community structure associated with two marine sponges, Hyrtios sp. 604 and Callyspongia sp. 612 collected from the South Pacific Ocean were analyzed by 16S rDNA-denaturing gradient gel electrophoresis (DGGE). The phylogenetic analysis showed that the bacterial community associated with Hyrtios sp. 604 contained diverse bacterial groups such as Chloroflexi, Firmicutes, Cyanobacteria, Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, and Acidobacteria. Callyspongia sp. 612 harbored Chloroflexi, Cyanobacteria, Alphaproteobacteria, and Gammaproteobacteria. Hyrtios sp. 604 belonging to genus Hyrtios known to produce natural products showed greater bacterial diversity than Callyspongia sp. 612. Phylum Actinobacteria was shown to be one of dominant bacterial groups in Hyrtios sp. 604. Although the same phyla of bacteria were found in both sponge species, the spongeassociated predominant bacterial groups differed between the two sponges with different chemical characteristics from the same geographical location. Uncultured bacteria represented over 90% of the bacteria diversity present in all bacterial communities of the sponges.
Biodiversity and Phylogenetic Analysis of Streptomyces Collected from Bamboo Forest Soil
Lee, Hyo-Jin ; Whang, Kyung-Sook ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 262~269
To investigate a quantitative evaluation of the actinobacteria, we have collected samples from various kinds of bamboo forest soil. Each different layers contained
CFU/g of actinobacteria which was the highest in litter layers of Sasa boreali forest soil. We obtained 330 actinobacteria from different layers of bamboo forest soil; litter (100 strains), humus (70 strains), and rhizosphere soil (160 strains). Based on the colony morphology (aerial mycelium, substrate mycelium, and soluble pigment), isolates were divided into thirty-six groups and we selected 50 representative isolates. 16S rRNA gene sequence analysis showed Streptomyces was major actinobacteria (94%) and they were categorized as cluster I (2 strains), II (35 strains), III (6 strains), and IV (7 strains), respectively. The diversity index of 50 Streptomyces collected from the bamboo forest soil was calculated with the Shannon-Wiener method. Bamboo litter showed higher diversity index level of 3.33 than that of humus and rhizosphere soil. Also, antibiotic activities of our isolates were investigated against Botrytis cinerea, Xanthomonas campestris, Xanthomonas axonopodis pv. vesicatoria, and Bacillus cereus and found in 74, 16, 25, and 24 strains, respectively.
Isolation of Bacillus licheniformis Producing Antimicrobial Agents against Bacillus cereus and Its Properties
Kim, Yong-Sang ; Yun, Suk-Hyun ; Jeong, Do-Yeon ; Hahn, Kum-Su ; Uhm, Tai-Boong ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 270~277
In order to manufacture Bacillus cereus-free fermented soybean products, an antimicrobial agentproducing isolate against B. cereus was obtained from 150 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 121057 was most closely related to Bacillus licheniformis. The B. licheniformis isolate began to produce the antimicrobial agent after 48 h of incubation. The agent was nonproteinaceous and insensitive to heat, long term storage and protease K. Electron microscopic observation indicated that the agent attacked the membrane of B. cereus, leaving the ghost cell. The isolate inhibited growth of B. subtilis, Lactobacillus brevis and various types of pathogenic strains including Escherichia coli, E. faecalis, Micrococcus luteus, Staphylococcus aureus, Aspergillus flavus, A. ochraceus, and A. parasiticus as well as B. cereus. After coinoculation of B. licheniformis SCK 121057 and B. cereus in the ratio (as the basis of CFU/g sample) of 10 to 1 on the surface of cooked soybeans, cell numbers of B. cereus had been dramatically reduced after 31 days of incubation compared to those of single inoculation of B. cereus.
Isolation and Phylogenetic Characteristics of Exopolysaccharide Producing Bacteria in a Rhizosphere Soil of Medicinal Herbs
Lee, Hae-Ran ; Kim, Ki-Kwhang ; Whang, Kyung-Sook ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 278~285
We examined the distribution of exopolysaccharide (EPS) producing bacteria population in rhizosphere soils of domestic medicinal herbs; Angelica sinensis, Atractytodes japonica, Achyranthes japonica, Anemarrhena asphodeloides, and Astragalus membranaceus. Fifty-six percent of the total isolates from rhizosphere soil of Angelica sinensis were EPS producing bacteria, suggesting the dominance of EPS producing bacteria in rhizosphere soil of Angelica sinensis. EPS producing bacteria were enumerated in root system (rhizosphere soil, rhizoplane, inside of root) of Angelica sinensis. Bacterial density of rhizosphere soil, rhizoplane, and inside of root were distributed
, respectively. EPS producing bacteria from rhizosphere soil were categorized into five major phylogenetic groups: Alphaproteobacteria (4 strains), Betaproteobacteria (6 strains), Firmicutes (2 strains), Actinobacteria (3 strains), and Bacteroidetes (1 strain) subdivisions. Also, the EPS producing isolates from rhizoplane were distributed as 7 strains in Alphaproteobacteria, 3 strains in Betaproteobacteria, 2 strains in Actinobacteria, 3 strains in Bacteroidetes, and 1 strain in Acidobacteria subdivisions. All of the EPS producing bacteria inside of root belong to genus Chitinophaga. Burkholderia caribiensis DR14, Terriglobus sp. DRP35, and Rhizobium hainanense SAP110 were selected in 112 EPS producing bacteria. These appeared to have produced high levels of exopolysaccharide 6,555 mpa.s, 3,275 mpa.s, and 1,873 mpa.s, respectively. The purified EPS was analyzed Bio-LC. As neutral sugars, glucose, galactose, mannose were detected and as amino sugars, galactosamine and glucosamine were detected. Especilally, analysis of Bio-LC showed that Rhizobium hainanense SAP110 produced glucose (60~89%) and glucosamine (8.5%) as major neutral sugar and amino sugar, respectively.
Prokaryotic Communities of Halophilic Methylotrophs Enriched from a Solar Saltern
Kim, Jong-Geol ; Park, Soo-Je ; Rhee, Sung-Keun ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 286~290
C-1 compounds are observed in anaerobic sediment of high salt environments. Thus, surface sediments and waters from these environments are therefore potential habitats for aerobic methylotrophic microorganisms. The soil samples collected from saltern and tidal flat as inoculums and methanol as carbon and energy source was supplied. After subculture depending on the salt concentration, methanol oxidizing bacteria growth condition investigated, the results of methanol oxidizing bacteria can grow in salt conditions, and the maximum concentration was 20%. Analysis based on denaturing gradient gel electrophoresis of 16S rRNA genes indicates that Methelyophaga-like bacteria were dominants of methylotrophs in the enrichment culture. Quantitative PCR showed that archaeal cells were about 1-10% of bacterial cells. Additionally archaea were assumed not to be involved in methanol oxidation since bacterial antibiotics completely blocked the methanol oxidation. Our results suggest that Methelyophaga-like bacteria could be involved in C-1 compounds oxidation in hypersaline environments although those activities are sensitive to salinity above 20%.
Simple and Rapid Extraction of a Bacteriocin Produced by Streptococcus parauberis Z49 from Fermented Cultures
Park, Hong-Je ; Khang, Yong-Ho ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 291~295
A novel bacteriocin produced by Streptococcus parauberis Z49 strain was characterized and efficiently extracted from fermented cultures by use of aqueous two-phase systems. The nisin-like bacteriocin, which was active even after a heat treatment at
for 15 min and in the broad pH range from 2 to 12, showed inhibition of bacterial growth of Micrococcus luteus, Lactobacillus spp., Lactobacillus fermentum, Enterococcus faecium, Listereia monocytogenes, and Pseudomonas fluorescens. Optimal conditions of PEG 600/
aqueous two-phase systems for the simple and rapid extraction of a novel bacteriocin were determined to be PEG 600 15%,
30%, and NaCl 8%, where the bacteriocin was concentrated in PEG layer.
Divergence Analysis of 16S rRNA and rpoB Gene Sequences Revealed from the Harmful Cyanobacterium Microcystis aeruginosa
Ki, Jang-Seu ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 296~302
Microcystis (Cyanobacteria, Chroococcales) is one of the green tide-causing organisms in freshwaters, and some species produce microcystin that is hepatotoxin. In the aspects of freshwater quality controls and health concerns, therefore it is necessary to manage the harmful organisms. In the present study, RNA polymerase beta subunit (rpoB) gene sequences of Microcystis were determined and characterized in order to use a potential marker for the molecular detections of the species. Microcystis rpoB showed high divergences of DNA similarity and genetic distances when compared with those of 16S rRNA, and the molecular differences were statistically significant (Student t-test, p<0.05). Parsimony analyses showed the rpoB gene evolves more than 2-fold faster than 16S rRNA. In addition, phylogeny of the rpoB gene separated each M. aeruginosa strain more clearly compared with a 16S rRNA tree. This study found that the order Chroococcales, including Microcystis, has approximately two rRNA operons and single copy of the rpoB gene in their chromosomes. These results suggest that the rpoB gene is a useful marker for the molecular phylogenetics and the detection of Microcystis.
Analysis of Integron-Associated Multi-Drug Resistance of Acinetobacter baumannii Isolated in Korea
Kim, Seong-Hwan ; Choi, Ji-Hye ; Park, Eun-Jin ; Suh, In-Won ; Son, Seung-Yeol ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 303~307
Acinetobacter baumannii 1625, a clinical isolate identified by Vitek and 16S rDNA sequence, showed an extended resistance to most
-lactams including imipenem, kanamycin, gentamicin, tobramycin, and cephalosporins of the third and fourth generations, and produced metallo-
-lactamase (MBL) of IMP-1 type which is rare in Korea. The isolate contained a class 1 integron of about 2.5 kb in size and the integron included accA4 (aminoglycoside resistance gene),
(carbapenem resistance gene), and
-lactam resistance gene) gene cassettes in order. The coexistence of IMP-1 type and OXA-2 type
-lactamase gene cassettes in an integron has not been reported in Korea. The transformed integron rendered the E. coli transformant resistant more than eight folds against imipenem, ampicilin, piperacillin, cefazolin, cefoperazone, and aztreonam comparing to the reference strain. This study clearly showed that the extended multi-drug resistance of A. baumannii 1625 was mainly due to the integron.
Characteristics of Xylan Degradation and HPLC Analysis of Hydrolyzed Xylans by Deinococcus geothermalis
Im, Seong-Hun ; Joe, Min-Ho ; Jung, Sun-Wook ; Lim, Sang-Yong ; Song, Hyun-Pa ; Kim, Dong-Ho ;
The Korean Journal of Microbiology, volume 46, issue 3, 2010, Pages 308~312
Deinococcus geothermalis is a moderate thermophillic radiation resistant bacterium producing greater abundance of sugar metabolism enzymes than other Deinococcus species. In this study, optimal condition for xylanolytic activity of D. geothermalis was determined and xylooligosaccharides from oat spelt, beechwood, and birchwood xylan hydrolysates by this organism were analyzed through HPLC. Reducing sugar yield was increased in the order of beechwood, birchwood, and oat spelt xylan. D. geothermalis displayed maximal xylanolytic activity at
and pH 8.0. Magnesium ion increased xylanolytic activity upto 7.5 fold. Six kinds of xylooligosaccharides (xylose, xylobios, xylotriose, xylotetraose, xylopentaose, and xylohexalose) were detected from beechwood and birchwood xylan reaction products. Among them, xylose was the major product. However, only three kinds of xylooligosaccharides (xylose, xylopentaose, and xylohexalose) were clearly detected from oat spelt xylan. Gamma-ray (50 kGy) treatment of beechwood xylan, birchwood xylan and oat spelt xylan increased xylanolytic activity of D. geothermalis. The results indicate that D. geothermalis and pretreatment of radiation is useful for xylooligosaccharides production.