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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Microbiology and Biotechnology
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The Korean Society for Applied Microbiology and Biotechnology
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Volume 17, Issue 12 - Dec 2007
Volume 17, Issue 11 - Nov 2007
Volume 17, Issue 10 - Oct 2007
Volume 17, Issue 9 - Sep 2007
Volume 17, Issue 8 - Aug 2007
Volume 17, Issue 7 - Jul 2007
Volume 17, Issue 6 - Jun 2007
Volume 17, Issue 5 - May 2007
Volume 17, Issue 4 - Apr 2007
Volume 17, Issue 3 - Mar 2007
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Volume 17, Issue 1 - Jan 2007
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Prions and Prion Diseases: Fundamentals and Mechanistic Details
Ryou, Chong-Suk ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1059~1070
Prion diseases, often called transmissible spongiform encephalopathies (TSEs), are infectious diseases that accompany neurological dysfunctions in many mammalian hosts. Prion diseases include Creutzfeldt-Jakob disease (CJD) in humans, bovine spongiform encephalopathy (BSE, "mad cow disease") in cattle, scrapie in sheep, and chronic wasting disease (CWD) in deer and elks. The cause of these fatal diseases is a proteinaceous pathogen termed prion that lacks functional nucleic acids. As demonstrated in the BSE outbreak and its transmission to humans, the onset of disease is not limited to a certain species but can be transmissible from one host species to another. Such a striking nature of prions has generated huge concerns in public health and attracted serious attention in the scientific communities. To date, the potential transmission of prions to humans via foodborne infection and iatrogenic routes has not been alleviated. Rather, the possible transmission of human to human or cervids to human aggravates the terrifying situation across the globe. In this review, basic features about prion diseases including clinical and pathological characteristics, etiology, and transmission of diseases are described. Based on recently accumulated evidences, the molecular and biochemical aspects of prions, with an emphasis on the molecular interactions involved in prion conversion that is critical during prion replication and pathogenesis, are also addressed.
Tylosin Production by Streptomyces fradiae Using Raw Cornmeal in Airlift Bioreactor
Choi, Du-Bok ; Choi, On-You ; Shin, Hyun-Jae ; Chung, Dong-Ok ; Shin, Dae-Yewn ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1071~1078
Using a 50-1 airlift bioreactor, for the effective production of tylosin from Streptomyces fradiae TM-224 using raw cornmeal as the energy source, various environmental factors were studied in flask cultures. The maximum tylosin concentration was obtained at
and pH between 7.0 and 7.5. When seed was inoculated after 24 h of culture, the maximum tylosin concentration, 5.7 g/l, was obtained after 4 days of culture. Various concentrations of raw cornmeal were tested to investigate the optimum initial concentration for the tylosin production. An initial raw cornmeal concentration of 80 g/l gave the highest tylosin concentration, 5.8 g/l, after 5 days of culture. Of the various nitrogen sources, soybean meal and fish meal were found to be the most effective for the production of tylosin. In particular, with the optimal mixing ratio, 12 g/l of soybean meal to 14 g/l of fish meal, 7.2 g/l of tylosin was obtained after 5 days of culture. To compare raw cornmeal and glucose for the production of tylosin in the 50-1 airlift bioreactor for 10 days, fed-batch cultures were carried out under the optimum culture conditions. When raw com meal was used as the energy source, the tylosin production increased with increasing culture time. The maximum tylosin concentration after 10 days of culture was 13.5 g/l, with a product yield from raw cornmeal of 0.123 g/g of consumed carbon source, which was about 7.2 times higher than that obtained when glucose was used as the carbon source.
Generation of FISH Probes Using Laser Microbeam Microdissection and Application to Clinical Molecular Cytogenetics
Shim, Sung-Han ; Kyhm, Jee-Hong ; Chung, Sung-Ro ; Kim, Seung-Ryong ; Park, Moon-Il ; Lee, Chul-Hoon ; Cho, Youl-Hee ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1079~1082
Chromosome microdissection and the reverse FISH technique is one of the most useful methods for the identification of structurally abnormal chromosomes. In particular, the laser microbeam microdissection (LMM) method allows rapid isolation of a target chromosome or a specific region of chromosomes without damage of genetic materials and contamination. Isolated chromosomes were directly amplified by the degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR), and then the FISH probes labeled with spectrum green- or spectrum red-dUTP were generated by nick-translation. Whole chromosome painting (WCP) probes were successfully generated from only 5 copies of the chromosome. With this method, we produced 24 WCP probes for each human chromosome. We also tried to characterize a marker chromosome, which seemed to be originated from chromosome 11 on conventional banding technique. The marker chromosomes were isolated by the LMM method and analyzed by reverse FISH. We elucidated that the marker chromosome was originated from the short arm of chromosome 5 (
). A fully automated and computer-controlled LMM method is a very simple laboratory procedure, and enables rapid and precise characterization of various chromosome abnormalities.
The Analysis and Application of a Recombinant Monooxygenase Library as a Biocatalyst for the Baeyer- Villiger Reaction
Park, Ji-Yeoun ; Kim, Dong-Hyun ; Kim, Su-Jin ; Kim, Jin-Hee ; Bae, Ki-Hwan ; Lee, Choong-Hwan ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1083~1089
Because of their selectivity and catalytic efficiency, BVMOs are highly valuable biocatalysts for the chemoenzymatic synthesis of a broad range of useful compounds. In this study, we investigated the microbial Baeyer-Villiger oxidation and sulfoxidation of thioanisole and bicyclo[3.2.0]hept-2-en-6-one using whole Escherichia coli cells that recombined with each of the Baeyer-Villiger monooxygenases originated from Pseudomonas aeruginosa PAOl and two from Streptomyces coelicolor A3(2). The three BVMOs were identified in the microbial genome database by a recently described protein sequence motif; e.g., BVMO motif(FXGXXXHXXXW). The reaction products were identified as (R)-/(S)-sulfoxide and 2-oxabicyclo/3-oxabicyclo[3.3.0]oct-6-en-2-one by GC-MS analysis. Consequently, this study demonstrated that the three enzymes can indeed catalyze the Baeyer-Villiger reaction as a biocatalyst, and effective annotation tools can be efficiently exploited as a source of novel BVMOs.
Cloning, Purification, and Characterization of a New DNA Polymerase from a Hyperthermophilic Archaeon, Thermococcus sp. NA1
Kim, Yun-Jae ; Lee, Hyun-Sook ; Bae, Seung-Seob ; Jeon, Jeong-Ho ; Lim, Jae-Kyu ; Cho, Yon-A ; Nam, Ki-Hoon ; Kang, Sung-Gyun ; Kim, Sang-Jin ; Kwon, Suk-Tae ; Lee, Jung-Hyun ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1090~1097
Genomic analysis of Thermococcus sp. NA1 revealed the presence of a 3,927-base-pair (bp) family B-type DNA polymerase gene, TNA1_pol. TNA1_pol, without its intein, was overexpressed in Escherichia coli, purified using metal affinity chromatography, and characterized. TNA1_pol activity was optimal at pH 7.5 and
. TNA1_pol was highly thermostable, with a half-life of 3.5h at
and 12.5h at
. Polymerase chain reaction parameters of TNA1_pol such as error-rate, processivity, and extension rate were measured in comparison with rTaq, Pfu, and KOD DNA polymerases. TNA1_pol averaged one incorrect bp every 4.45 kilobases (kb), and had a processivity of 150 nucleotides (nt) and an extension rate of 60 bases/s. Thus, TNA1_pol has a much faster elongation rate than Pfu DNA polymerase with 7-fold higher fidelity than that of rTaq.
Molecular Modeling and its Experimental Verification for the Catalytic Mechanism of Candida antarctica Lipase B
Kwon, Cheong-Hoon ; Shin, Dae-Young ; Lee, Jong-Ho ; Kim, Seung-Wook ; Kang, Jeong-Won ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1098~1105
Quantum mechanical and molecular dynamics simulation analysis has been performed on the model system for CALB (Candida antarctica lipase B) with esters to study the reaction mechanism and conformational preference of catalytic hydrolysis and the esterification reaction. Using quantum mechanical analysis, the ping-pong bi-bi mechanism was applied and energies and 3-dimensional binding configurations of the whole reaction pathways were calculated. Further molecular dynamics simulation analysis was performed on the basis of the transition state obtained from quantum mechanical study to observe the effect of structures of the substrates. Calculation results using substrates of different chain length and chiral configurations were compared for conformational preference. The calculated results showed very small influence on chain length, whereas chiral conformation showed big differences. Calculated results from molecular modeling studies have been compared qualitatively with the experimental data using racemic mixtures of (
)-cis-4-acetamido-cyclopent-2-ene-1-ethyl acetate as substrates.
Cloning and Characterization of Squalene Synthase (SQS) Gene from Ganoderma lucidum
Zhao, Ming-Wen ; Liang, Wan-Qi ; Zhang, Da-Bing ; Wang, Nan ; Wang, Chen-Guang ; Pan, Ying-Jie ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1106~1112
This report provides the complete nucleotide sequences of the full-length cDNA encoding squalene synthase (SQS) and its genomic DNA sequence from a triterpene-producing fungus, Ganoderma lucidum. The cDNA of the squalene synthase (SQS) (GenBank Accession Number: DQ494674) was found to contain an open reading frame (ORF) of 1,404 bp encoding a 468-amino-acid polypeptide, whereas the SQS genomic DNA sequence (GenBank Accession Number: DQ494675) consisted of 1,984 bp and contained four exons and three introns. Only one gene copy was present in the G. lucidum genome. The deduced amino acid sequence of Ganoderma lucidum squalene synthase (GI-SQS) exhibited a high homology with other fungal squalene synthase genes and contained six conserved domains. A phylogenetic analysis revealed that G. lucidum SQS belonged to the fungi SQS group, and was more closely related to the SQS of U. maydis than to those of other fungi. A gene expression analysis showed that the expression level was relatively low in mycelia incubated for 12 days, increased after 14 to 20 days of incubation, and reached a relatively high level in the mushroom primordia. Functional complementation of GI-SQS in a SQS-deficient strain of Saccharomyces cerevisiae confirmed that the cloned cDNA encoded a squalene synthase.
Effects of Culture Conditions on Osteogenic Differentiation in Human Mesenchymal Stem Cells
Song, Su-Jin ; Jeon, O-Ju ; Yang, Hee-Seok ; Han, Dong-Keun ; Kim, Byung-Soo ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1113~1119
Human bone marrow-derived mesenchymal stem cells (hBMMSCs) must differentiate into osteogenic cells to allow for successful bone regeneration. In this study, we investigated the effects of different combinations of three soluble osteogenic differentiation-inducing factors [L-ascorbic acid (AC),
), and bone morphogenic protein-2 (BMP-2)] and the presence of a hydroxyapatite (HA) substrate on hBMMSC osteogenic differentiation in vitro. hBMMSCs were cultured in medium containing various combinations of the soluble factors on culture plates with or without HA coating. After 7 days of culture, alkaline phosphatase (ALP) activity, calcium deposition, and osteoprotegerin (OPG) and osteopontin (OPN) expression were measured. The effects of individual and combined factors were evaluated using a factorial analysis method. BMP-2 predominantly affected expression of early markers of osteogenic differentiation (ALP and OPG). HA had the highest positive effect on OPN expression and calcium deposition. The interaction between AC,
, and HA had the second highest positive effect on ALP activity.
Assessment of Lipopolysaccharide-binding Activity of Bifidobacterium and Its Relationship with Cell Surface Hydrophobicity, Autoaggregation, and Inhibition of Interleukin-8 Production
Park, Myeong-Soo ; Kim, Min-Jeong ; Ji, Geun-Eog ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1120~1126
This study was performed to screen probiotic bifidobacteria for their ability to bind and neutralize lipopolysaccharides (LPS) from Escherichia coli and to verify the relationship between LPS-binding ability, cell surface hydrophobicity (CSH), and inhibition of LPS-induced interleukin-8 (IL-8) secretion by HT-29 cells of the various bifidobacterial strains. Ninety bifidobacteria isolates from human feces were assessed for their ability to bind fluorescein isothiocyanate (FITC)-labeled LPS from E. coli. Isolates showing 30-60% binding were designated LPS-high binding (LPS-H) and those with less than 15% binding were designated LPS-low binding (LPS-L). The CSH, autoaggregation (AA), and inhibition of LPS-induced IL-8 release from HT-29 cells of the LPS-H and LPS-L groups were evaluated. Five bifidobacteria strains showed high levels of LPS binding, CSH, AA, and inhibition of IL-8 release. However, statistically significant correlations between LPS binding, CSH, AA, and reduction of IL-8 release were not found. Although we could isolate bifidobacteria with high LPS-binding ability, CSH, AA, and inhibition of IL-8 release, each characteristic should be considered as strain dependent. Bifidobacteria with high LPS binding and inhibition of IL-8 release may be good agents for preventing inflammation by neutralizing Gram-negative endotoxins and improving intestinal health.
Bifidus Fermentation Increases Hypolipidemic and Hypoglycemic Effects of Red Ginseng
Trinh, Hien-Trung ; Han, Sang-Jun ; Kim, Sang-Wook ; Lee, Young-Chul ; Kim, Dong-Hyun ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1127~1133
Antihyperlipidemic and antihyperglycemic effects of Red Ginseng (RG, steamed and dried root of Panax ginseng C.A.Meyer, family Araliaceae), major component of which is ginsenoside Rg3, and Bifidodoterium-fermented RG (FRG), major component of which is ginsenoside Rh2, were investigated. Orally administered RG and FRG potently reduced the serum triglyceride levels in com-oil-induced hypertriglycemidemic mice as well as total cholesterol and triglyceride levels in Triton WR-1339-induced hyperlipidemic mice. Of the saponin and polysaccharide fractions of RG and FRG, the polysaccharide fraction inhibited postprandial blood glucose elevation of maltose- or starch-loaded mice and reduced the blood triglyceride levels in com-oil-induced hypertriglycemidemic mice. The saponin fraction and its ginsenosides Rg3 and Rh2 reduced blood triglyceride and total cholesterol levels in Triton WR1339-induced hyperlipidemic mice. The inhibitory effect of FRG and its main constituents against hyperlipidemia and hyperglycemia in mice were more potent than those of RG. These findings suggest that hypolipidemic and hypoglycemic effects of RG can be enforced by Bifidus fermentation and FRG may improve hyperlipidemia and hyperglycemia.
Inhibitory Effects of Cordycepin (3'-Deoxyadenosine), a Component of Cordyceps militaris, on Human Platelet Aggregation Induced by Thapsigargin
Cho, Hyun-Jeong ; Cho, Jae-Youl ; Rhee, Man-Hee ; Kim, Hyeong-Soo ; Lee, Hyun-Sub ; Park, Hwa-Jin ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1134~1138
Cordycepin (3'-deoxyadenosine) is an adenosine analog, isolated from Cordyceps militaris, and it has been used as an anticancer and anti-inflammation ingredient in traditional Chinese medicine. We investigated the effects of cordycepin (3'-deoxyadenosine) on human platelet aggregation, which was induced by thapsigargin, a tumor promoter, and determined the cytosolic free
) (an aggregation-stimulating molecule) and cyclic-guanosine monophosphate (cGMP) (an aggregation-inhibiting molecule). Cordycepin inhibited thapsigargin-induced platelet aggregation in a dose-dependent manner, and it clearly reduced the levels of
, which was increased by thapsigargin (
) or U46619 (
). Cordycepin also increased the thapsigargin-reduced cGMP levels. Accordingly, our data demonstrated that cordycepin may have a beneficial effect on platelet aggregation-mediated thrombotic diseases through the
-regulating system such as cGMP.
The Effect of Pulse Electric Field on Accumulation of Selenium in Cells of Saccharomyces cerevisiae
Pankiewicz, Urszula ; Jamroz, Jerzy ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1139~1146
Cultures of Saccharomyces cerevisiae were subjected to the effect of PEF (pulse electric field) and a source of selenium. The culture period after which yeast cells were subjected to PEF treatment was optimized, as was the duration of the exposure. Optimization of the nutrient medium composition in S. cerevisiae cultures resulted in an over 1.8-fold increase in selenium accumulation with relation to cultures on the initial substrate. Optimization of the pH value and of culture duration resulted in selenium accumulation increase by approximately 78%. A significant correlation was found between the accumulation of selenium in yeast cells and its concentration in the culture substrate. The highest accumulation of selenium in the biomass of yeast, approx.
d.m., was obtained after 15-min exposure to PEF on a 20-h culture. An approx. 50% higher content of selenium in cells was recorded, as compared with the control culture without the application of PEF.
Biodegradation of Endocrine-disrupting Bisphenol A by White Rot Fungus Irpex lacteus
Shin, Eun-Hye ; Choi, Hyoung-Tae ; Song, Hong-Gyu ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1147~1151
Biodegradation of endocrine-disrupting bisphenol A was investigated with several white rot fungi (Irpex lacteus, Trametes versicolor, Ganoderma lucidum, Polyporellus brumalis, Pleurotus eryngii, Schizophyllum commune) isolated in Korea and two transformants of T. versicolor (strains MrP 1 and MrP 13). I. lacteus degraded 99.4% of 50 mg/l bisphenol A in 3 h incubation and 100% in 12 h incubation. which was the highest degradation rate among the fungal strains tested. T. versicolor degraded 98.2% of 50 mg/l bisphenol A in 12 h incubation. Unexpectedly, the transformant of the Mn-repressed peroxidase gene of T. versicolor, strain MrP 1, degraded 76.5% of 50 mg/l bisphenol A in 12 h incubation, which was a lower degradation rate than wild-type T. versicolor. The removal of bisphenol A by I. lacteus occurred mainly by biodegradation rather than adsorption. Optimum carbon sources for biodegradation of bisphenol A by I. lacteus were glucose and starch, and optimum nitrogen sources were yeast extract and tryptone in a minimal salts medium; however, bisphenol A degradation was higher in nutrient-rich YMG medium than that in a minimal salts medium. The initial degradation of endocrine disruptors was accompanied by the activities of manganese peroxidase and laccase in the culture of I. lacteus.
Production of Monoclonal Antibody Against Listeria monocytogenes and Its Application to Immunochromatography Strip Test
Shim, Won-Bo ; Choi, Jin-Gil ; Kim, Ji-Young ; Yang, Zheng-You ; Lee, Kyu-Ho ; Kim, Min-Gon ; Ha, Sang-Do ; Kim, Keun-Sung ; Kim, Kwang-Yup ; Kim, Cheol-Ho ; Ha, Kwang-Soo ; Eremin, Sergei A. ; Chung, Duck-Hwa ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1152~1161
An immunochromatography (ICG) strip test based on a monoclonal antibody for the rapid detection of L. monocytogenes in meat and processed-meat samples was developed in this study. A monoclonal antibody (MAb) specific to L. monocytogenes was produced from cloned hybridoma cells (FKLM-3B12-37) and used to develop an ICG strip test. The antibody showed a stronger binding to L. monocytogenes than other Listeria species, and a weak cross-reaction to S. aureus based on an ELISA. The detection limit of the ICG strip test was
. In total, 116 meat and processed-meat samples were collected and analyzed using both the ICG strip test and a PCR. The ICG strip test and PCR indicated L. monocytogenes contamination in 34 and 27 meat samples, respectively. The 7 meat samples not identified as L. monocytogenes positive by the PCR were also tested using an API kit and found to be contaminated by Listeria species. In conclusion, the ICG strip test results agreed well with those obtained using the PCR and API kit. Thus, the developed ICG has potential use as a primary screening tool for L. monocytogenes in various foods and agricultural products, generating results within 20 min without complicated steps.
Development of a Novel Vector System for Programmed Cell Lysis in Escherichia coli
Yun, Ji-Ae ; Park, Ji-Hye ; Park, Nan-Joo ; Kang, Seo-Won ; Ryu, Sang-Ryeol ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1162~1168
Although widely used as a host for recombinant protein production, Escherichia coli is unsuitable for massive screening of recombinant clones, owing to its poor secretion of proteins. A vector system containing T4 holin and T7 lysozyme genes under the control of the ptsG promoter derivative that is inducible in the absence of glucose was developed for programmed cell lysis of E. coli. Because E. coli harboring the vector grows well in the presence of glucose, but is lysed upon glucose exhaustion, the activity of the foreign gene expressed in E. coli can be monitored easily without an additional step for cell disruption after the foreign gene is expressed sufficiently with an appropriate concentration of glucose. The effectiveness of the vector was demonstrated by efficient screening of the amylase gene from a Bacillus subtilis genomic library. This vector system is expected to provide a more efficient and economic screening of bioactive products from DNA libraries in large quantities.
Cloning of Four Genes Involved in Limonene Hydroxylation from Enterobacter cowanii 6L
Yang, Eun-Ju ; Park, Yeon-Jin ; Chang, Hae-Choon ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1169~1176
Genes encoding proteins responsible for limonene catabolism were cloned from a limonene-degrading microorganism, Enterobacter cowanii 6L, which was isolated from citron (Citrus junos) peel. The 8.6, 4.7, and 7.7 kb fragments (CD3, CD4, and CD6) of E. cowanii 6L chromosomal DNA that confer to E. coli the ability to grow on limonene have been cloned and their corresponding DNA sequences were determined. Nine open reading frames (ORFs) were identified, and the four ORFs (921 bp of CD3-2; 1,515 bp of CD4-1; 1,776 bp of CD6-1; and 1,356 bp of CD6-2) that encode limonene hydroxylase were confirmed by independently expressing these genes in E. coli. FAD and NADH were found to stimulate the hydroxylation reaction if added to cell extracts from E. coli recombinants, and multiple compounds (linalool, dihydrolinalool, perillyl alcohol, (
) were the principal products observed. Our results suggest that the isolate E. cowanii 6L has a broad metabolic capability including utilization of limonene. This broad metabolic ability was confirmed by identifying four novel limonene hydroxylase functional ORFs in E. cowanii 6L.
Simultaneous Detection and Identification of Bacillus cereus Group Bacteria Using Multiplex PCR
Park, Si-Hong ; Kim, Hyun-Joong ; Kim, Jae-Hwan ; Kim, Tae-Woon ; Kim, Hae-Yeong ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1177~1182
Bacillus cereus group bacteria share a significant degree of genetic similarity. Thus, to differentiate and identify the Bacillus cereus group efficiently, a multiplex PCR method using the gyrB and groEL genes as diagnostic markers is suggested for simultaneous detection. The assay yielded a 400 bp amplicon for the groEL gene from all the B. cereus group bacteria, and a 253 bp amplicon from B. anthracis, 475 bp amplicon from B. cereus, 299 bp amplicon from B. thuringiensis, and 604 bp amplicon from B. mycoides for the gyrB gene. No nonspecific amplicons were observed with the DNA from 29 other pathogenic bacteria. The specificity and sensitivity of the B. cereus group identification using this multiplex PCR assay were evaluated with different kinds of food samples. In conclusion, the proposed multiplex PCR is a reliable, simple, rapid, and efficient method for the simultaneous identification of B. cereus group bacteria from food samples in a single tube.
Effect of 3,3',4',5-Tetrachlorosalicylanilide on Reduction of Excess Sludge and Nitrogen Removal in Biological Wastewater Treatment Process
Rho, Sang-Chul ; Nam, Gil-Nam ; Shin, Jee-Young ; Jahng, Deok-Jin ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1183~1190
A metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (TCS), was used to reduce excess sludge production in biological wastewater treatment processes. Batch experiments confirmed that 0.4 mg/l of TCS reduced the aerobic growth yield of activated sludge by over 60%. However, the growth yield remained virtually constant even at the increased concentrations of TCS when cultivations were carried out under the anoxic condition. Reduction of sludge production yield was confirmed in a laboratory-scale anoxic-oxic process operated for 6 months. However, it was found that ammonia oxidation efficiency was reduced by as much as 77% in the presence of 0.8 mg/l of TCS in the batch culture. Similar results were also obtained through batch inhibition tests with activated sludges and by bioluminescence assays using a recombinant Nitrosomonas europaea (pMJ217). Because of this inhibitory effect of TCS on nitrification, the TCS-fed continuous system failed to remove ammonia in the influent. When TCS feeding was stopped, the nitrification yield of the process was resumed. Therefore, it seems to be necessary to assess the nitrogen content of wastewater if TCS is used for reducing sludge generation.
Detection and Kinetics of Mucosal Pathogenic Bacteria Binding with Polysaccharides
Chung, Kyong-Hwan ; Park, Jung-Soon ; Hwang, Hyun-Soo ; Kim, Jin-Chul ; Lee, Ki-Young ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1191~1197
The detection and kinetics of mucosal pathogenic bacteria binding on polysaccharide ligands were studied using a surface plasmon resonance biosensor. The kinetic model applied curve-fitting to the experimental surface plasmon resonance sensorgrams to evaluate the binding interactions. The kinetic parameters for the mucosal pathogenic bacteria (Pseudomonas aeruginosa, Pseudomonas fluorescens, Serratia marcescens) with the alginate ligand were determined from a kinetic model. In addition, the binding interactions of the mucosal pathogenic bacteria with polysaccharide binding pairs (Pseudomonas aeruginosa/alginate, Streptococcus pneumoniae/pneumococcal polysaccharide, Staphylococcus aureus/pectin) were also compared with their kinetic parameters. The rate constants of association for Pseudomonas aeruginosa with the alginate ligand were higher than those for Pseudomonas fluorescens. Serratia marcescens had no detectable interaction with the alginate ligand. The adhesion affinity of Pseudomonas aeruginosa with alginate was higher than that for the other binding pairs. The binding affinities of the pathogenic bacteria with their own polysaccharide were higher than that of Staphylococcus aureus with pectin. Measuring the contact angle was found to be a feasible method for detecting binding interactions between analytes and ligands.
Involvement of Extracellular Matrix and Integrin-like Proteins on Conidial Adhesion and Appressorium Differentiation in Magnaporthe oryzae
Bae, Cheol-Yong ; Kim, Soon-Ok ; Choi, Woo-Bong ; Lee, Yong-Hwan ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1198~1203
Conidial adhesion and appressorium formation of Magnaporthe oryzae on the rice surface are important early events in the infection process. As an initiative step to understand the mechanisms underlying these cellular processes at a biochemical level, the effect of a human fibronectin antibody (HFA) and RGD peptides on conidial adhesion and appressorium formation was evaluated. HFA inhibited conidial adhesion and appressorium formation in a dosage-dependent manner. RGD peptides also inhibited these cellular events. Conidial adhesion and appressorium formation inhibited by RGD peptides were restored by chemicals involved in the cyclic AMP-dependent signaling pathway. These results suggest that extracellular matrix proteins might be involved in conidial adhesion and appressorium formation through integrin-like receptor mediation and modulation of cAMP-dependent signaling in the cells.
Functional Analysis of the Residues C770 and G771 of E. coli 16S rRNA Implicated in Forming the Intersubunit Bridge B2c of the Ribosome
Kim, Hong-Man ; Yeom, Ji-Hyun ; Ha, Hye-Jung ; Kim, Jong-Myung ; Lee, Kang-Seok ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1204~1207
Structural analyses have shown that nucleotides at the positions 770 and 771 of Escherichia coli 16S rRNA are implicated in forming one of highly conserved intersubunit bridges of the ribosome, B2c. To examine a functional role of these residues, base substitutions were introduced at these positions and mutant ribosomes were analyzed for their protein synthesis ability using a specialized ribosome system. The results showed requirement of a pyrimidine at the position 770 for ribosome function regardless of the nucleotide identity at the position 771. Sucrose gradient profiles of ribosomes revealed that the loss of protein-synthesis ability of mutant ribosome bearing a base substitution from C to G at the position 770 stems from its inability to form 70S ribosomes. These findings indicate involvement of nucleotide at the position 770, not 771, in ribosomal subunit association and provide a useful rRNA mutation that can be used as a target to investigate the physical interaction between 16S and 23S rRNA.
Repeated Batch Production of Epothilone B by Immobilized Sorangium cellulosum
Park, Sang-Woo ; Park, Su-Jeong ; Han, Se-Jong ; Lee, Jin-Won ; Kim, Dong-Shik ; Kim, Ji-Heung ; Kim, Byung-Woo ; Lee, Jee-Won ; Sim, Sang-Jun ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1208~1212
Production of extracellular epothilone B, one of the potent anticancer agents, by free and immobilized Sorangium cellulosum was studied using the repeated batch culture process. The concentration of alginate used in immobilization was directly related to the mass transfer rate of nutrients, mechanical stability, and the epothilone B production yield. With the optimized 3% (w/v) calcium alginate carrier, a prolonged repeated batch culture was investigated for the 5 repeated batches for 24 days. The maximum productivity of epothilone B obtained from the alginate-immobilized cells was 5.03 mg/l/day, which is 3 times higher than that of free cells (1.68 mg/l/day).
Development of a Monitoring Vector for Leuconostoc mesenteroides Using the Green Fluorescent Protein Gene
Lee, Kwan-Hoon ; Park, Woo-Jung ; Kim, Joo-Yun ; Kim, Han-Geun ; Lee, Jung-Min ; Kim, Jeong-Hwan ; Park, Jeong-Woo ; Lee, Jong-Hoon ; Chung, Sung-Kyun ; Chung, Dae-Kyun ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1213~1216
The vector pCW5 with plasmid pC7, originally isolated in Lactobacillus paraplantarum C7 derived from kimchi, was constructed using a p32 strong promoter, the pC7 replicon, and green fluorescent protein (GFP) as the reporter. The constructed vector was transformed into E. coli and Leuconostoc mesenteroides, and GFP expression detected using a Western blot analysis. GFP fluorescence was recognized in E. coli and Leuconostoc mesenteroides using a confocal microscope. In addition, GFP fluorescence was also clearly detected in several industrially important lactic acid bacteria (LAB), including Lactobacillus bulgaricus, Lactobacillus paraplantarum, and Lactobacillus plantarum. Thus, pCW5 was shown to be effective for Leuconostoc mesenteroides when using GFP as the reporter, and it can also be used as a broad-host-range vector for other lactic acid bacteria.
Antifungal Cyclopeptolide from Fungal Saprophytic Antagonist Ulocladium atrum
Yun, Bong-Sik ; Kwon, Eun-Mi ; Kim, Jin-Cheol ; Yu, Seung-Hun ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1217~1220
The saprophytic fungus Ulocladium atrum Preuss is a promising biological control agent for Botrytis cinerea in greenhouse- and field-grown crops. However, despite its known potent antifungal activity, no antifungal substance has yet been reported. In an effort to characterize the antifungal substance from U. atrum, we isolated an antibiotic peptide. Based on extensive spectroscopic analyses, its structure was established as a cyclopeptolide with a high portion of N-methylated amino acids, and its
chemical shifts were completely assigned based on extensive 1D and 2D NMR experiments. Compound 1 exhibited potent antifungal activity against the plant pathogenic fungus Botrytis cinerea and moderate activity against Alternaria alternate and Magnaporthe grisea.
Batch and Continuous Culture Kinetics for Production of Carotenoids by
-Ionone-Resistant Mutant of Xanthophyllomyces dendrorhous
Park, Ki-Moon ; Song, Min-Woo ; Kang, Seog-Jin ; Lee, Jae-Heung ;
Journal of Microbiology and Biotechnology, volume 17, issue 7, 2007, Pages 1221~1225
-ionone-resistant mutant strain isolated from the red yeast Xanthophyllomyces dendrorhous KCTC 7704 was used for batch and continuous fermentation kinetic studies with glucose media in a 2.5-1 jar fermentor at
and pH 4.5. The kinetic pattern of growth and carotenoid concentration in the batch fermentations exhibited a so-called mixed-growth-associated product formation, possibly due to the fact that the content of intracellular carotenoids depends on the degree of physical maturation toward adulthood. To determine the maximum specific growth rate constant (
) and Monod constant (
) for the mutant, glucose-limited continuous culture studies were performed at different dilution rates within a range of
. A reciprocal plot of the steady-state data (viz., reciprocal of glucose concentration versus residence time) obtained from continuous culture experiments was used to estimate a
of 1.19 g/l. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content (
) for the mutant was estimated to be
dry cell weight, and the Lee constant (
), which was tentatively defined in this work, was found to be 3.0 h.