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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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Journal DOI :
The Korean Society for Applied Microbiology and Biotechnology
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Volume & Issues
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
Volume 17, Issue 2 - Feb 2007
Volume 17, Issue 1 - Jan 2007
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Nitrogen Control in Corynebacterium glutamicum: Proteins, Mechanisms, Signals
Burkovski, Burkovski ; Andreas, Andreas ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 187~194
In order to utilize different nitrogen sources and to survive in a situation of nitrogen limitation, microorganisms have developed sophisticated mechanisms to adapt their metabolism to a changing nitrogen supply. In this communication, the recent knowledge of nitrogen regulation in the amino acid producer Corynebacterium glutamicum is summarized. The core adaptations of C. glutamicum to nitrogen limitation on the level of transcription are controlled by the global regulator AmtR. Further components of the signal pathway are GlnK, a
signal transduction protein, and GlnD. Mechanisms involved in nitrogen control in C. glutamicum regulating gene expression and protein activity are repression of transcription, protein-complex formation, protein modification by adenylylation, change of intracellular localization, and proteolysis.
Effect of Culture Conditions on Canthaxanthin Production by Dietzia natronolimnaea HS-1
Khodaiyan Khodaiyan ; Faramarz Faramarz ; Razavi Seyed Hadi ; Emam-Djomeh Zahra ; Mousavi Seyed Mohammad Ali ; Hejazi Mohammad Amin ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 195~201
This study investigated the effects of various culture parameters (carbon sources, temperature, initial pH of culture, NaCl concentration, and light) on the growth and canthaxanthin production by Dietzia natronolimnaea HS-1. The results showed that the most effective carbon source for growth and canthaxantin production was glucose, and the best pH and temperature were 7 and
, respectively. In addition, the biomass and canthaxanthin production increased in a medium without NaCl and in the presence of light. Under the optimized conditions, the maximum biomass, total carotenoid, and canthaxanthin production were
, respectively, in an Erlenmeyer flask system, yet increased to 7.25 g/l, 5.48 mg/l, and 5.29 mg/l, respectively, in a batch fermenter system.
Morphology and Adhesion of Campylobacter jejuni to Chicken Skin Under Varying Conditions
Jang, Keum-Il ; Kim, Min-Gon ; Ha, Sang-Do ; Kim, Keun-Sung ; Lee, Kyu-Ho ; Chung, Duck-Hwa ; Kim, Cheorl-Ho ; Kim, Kwang-Yup ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 202~206
The adhesion of Campylobacter jejuni to chicken skin, along with the associated morphological changes under aerobic conditions at 4, 25, and
and microaerobic (
) conditions, were investigated using confocal laser scanning microscopy (CLSM), flow cytometry, and plate counting. The morphological change of C. jejuni from a spiral shape to a coccoid form or VBNC form (viable but nonculturable form) progressed rapidly under aerobic conditions at 25, 37, and
. As regards adhesion, the C. jejuni cells were mostly located in the crevices and feather follicles of the chicken skin, where the cells in the feather follicles floated freely in the entrapped water, even after the skin was rinsed quite thoroughly. CLSM also revealed the penetration of some spiral-shaped C. jejuni cells into the chicken skin. Even after changing their shape at various temperatures, coccoid-form C. jejuni cells were still found in the crevices and feather follicles of the chicken skin.
Comparative Proteomic Analyses of the Yeast Saccharomyces cerevisiae KNU5377 Strain Against Menadione-Induced Oxidative Stress
Kim, Il-Sup ; Yun, Hae-Sun ; Jin, In-Gnyol ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 207~217
The Saccharomyces0 cerevisiae KNU5377 strain, which was isolated from spoilage in nature, has the ability to convert biomass to alcohol at high temperatures and it can resist against various stresses [18, 19]. In order to understand the defense mechanisms of the KNU5377 strain under menadione (MD) as oxidative stress, we used several techniques for study: peptide mass fingerprinting (PMF) by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) followed by two-dimensional (2D) gel electrophoresis, liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), and surface-enhanced laser desorption ionization-time of flight (SELDI-TOF) technology. Among the 35 proteins identified by MALDI-TOF MS, 19 proteins including Sod1p, Sod2p, Tsa1p, and Ahp1p were induced under stress condition, while 16 proteins were augmented under normal condition. In particular, five proteins, Sod1p, Sod2p, Ahp1p, Rib3p, Yaf9p, and Mnt1p, were induced in only stressed cells. By LC-ESI-MS/MS analysis, 37 proteins were identified in normal cells and 49 proteins were confirmed in the stressed cells. Among the identified proteins, 32 proteins were found in both cells. Five proteins including Yel047cp and Met6p were only upregulated in the normal cells, whereas 17 proteins including Abp1P and Sam1p were elevated in the stressed cells. It was interesting that highly hypothetical proteins such as Ynl281wp, Ygr279cp, Ypl273wp, Ykl133cp, and Ykr074wp were only expressed in the stressed cells. SELDI-TOF analysis using the SAX2 and WCX2 chips showed that highly multiple-specific protein patterns were reproducibly detected in ranges from 2.9 to 27.0 kDa both under normal and stress conditions. Therefore, induction of antioxidant proteins, hypothetical proteins, and low molecular weight proteins were revealed by different proteomic techniques. These results suggest that comparative analyses using proteomics might contribute to elucidate the defense mechanisms of KNU5377 under MD stress.
Metabolic Characterization of Lactic Acid Bacterium Lactococcus garvieae sk11, Capable of Reducing Ferric Iron, Nitrate, and Fumarate
Yun, Su-Hee ; Hwang, Tae-Sik ; Park, Doo-Hyun ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 218~225
A lactic acid bacterium capable of anaerobic respiration was isolated from soil with ferric iron-containing glucose basal medium and identified as L. garvieae by using 16S rDNA sequence homology. The isolate reduced ferric iron, nitrate, and fumarate to ferrous iron, nitrite, and succinate, respectively, under anaerobic
atmosphere. Growth of the isolate was increased about 30-39% in glucose basal medium containing nitrate and fumarate, but not in the medium containing ferric iron. Specifically, metabolic reduction of nitrate and fumarate is thought to be controlled by the specific genes fnr, encoding FNR-like protein, and nir, regulating fumarate-nitrate reductase. Reduction activity of ferric iron by the isolate was estimated physiologically, enzymologically, and electrochemically. The results obtained led us to propose that the isolate metabolized nitrate and fumarate as an electron acceptor and has specific enzymes capable of reducing ferric iron in coupling with anaerobic respiration.
Production of Acyl-Homoserine Lactone Quorum-Sensing Signals is Wide-Spread in Gram-Negative Methylobacterium
Poonguzhall, Poonguzhall ; Selvaraj, Selvaraj ; Madhaiyan, Munusamy ; Sa, Tongmin ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 226~233
Members of Methylobacterium, referred as pink-pigmented facultative methylotrophic bacteria, are frequently associated with terrestrial and aquatic plants, tending to form aggregates on the phyllosphere. We report here that the production of autoinducer molecules involved in the cell-to-cell signaling process, which is known as quorum sensing, is common among Methylobacterium species. Several strains of Methylobacterium were tested for their ability to produce N-acyl-homoserine lactone (AHL) signal molecules using different indicators. Most strains of Methylobacterium tested could elicit a positive response in Agrobacterium tumefaciens harboring lacZ fused to a gene that is regulated by autoinduction. The synthesis of these compounds was cell-density dependent, and the maximal activity was reached during the late exponential to stationary phases. The bacterial extracts were separated by thin-layer chromatography and bioassayed with A. tumefaciens NTI (traR, tra::lacZ749). They revealed the production of various patterns of the signal molecules, which are strain dependent. At least two signal molecules could be detected in most of the strains tested, and comparison of their relative mobilities suggested that they are homologs of N-octanoyl-
-homoserine lactone (
) and N-decanoyl-
-homoserine lactone (
IVET-based Identification of Virulence Factors in Vibrio vulnificus MO6-24/O
Lee, Ko-Eun ; Bang, Ji-Sun ; Baek, Chang-Ho ; Park, Dae-Kyun ; Hwang, Won ; Choi, Sang-Ho ; Kim, Kum-Soo ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 234~243
Vibrio vulnificus is an opportunistic pathogen that causes septicemia in humans. To identify the genes associated with its pathogenicity, in vivo expression technology (IVET) was used to select genes specifically expressed in a host, yet not significantly in vitro. Random lacZ-fusions in the genome of V vulnificus strain MO6-24/O were constructed using an IVET vector, pSG3, which is a suicide vector containing promoterless-aph and -lacZ as reporter genes. A total of
resulting library clones were then intraperitoneally injected into BALB/c mice using a colony forming unit (CFU) of
. Two hours after infection, kanamycin was administered at
per gram of mouse weight. After two selection cycles, 11 genes were eventually isolated, which were expressed only in the host. Among these genes, VV20781 and VV21007 exhibiting a homology to a hemagglutinin gene and tolC, respectively, were selected based on having the highest frequency. When compared to wild-type cells, mutants with lesions in these genes showed no difference in the rate of growth rate, yet a significant decrease in cytotoxicity and the capability to form a biofilm.
Transcriptome Analysis of Phosphate Starvation Response in Escherichia coli
Baek, Jong-Hwan ; Lee, Sang-Yup ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 244~252
Escherichia coli has a PhoR-PhoB two-component regulatory system to detect and respond to the changes of environmental phosphate concentration. For the E. coli W3110 strain growing under phosphate-limiting condition, the changes of global gene expression levels were investigated by using DNA microarray analysis. The expression levels of some genes that are involved in phosphate metabolism were increased as phosphate became limited, whereas those of the genes involved in ribosomal protein or amino acid metabolism were decreased, owing to the stationary phase response. The upregulated genes could be divided into temporarily and permanently inducible genes by phosphate starvation. At the peak point showing the highest expression levels of the phoB and phoR genes under phosphate-limiting condition, the phoB- and/or phoR-dependent regulatory mechanisms were investigated in detail by comparing the gene expression levels among the wild-type and phoB and/or phoR mutant strains. Overall, the phoB mutation was epistatic over the phoR mutation. It was found that PhoBR and PhoB were responsible for the upregulation of the phosphonate or glycerol phosphate metabolism and high-affinity phosphate transport system, respectively. These results show the complex regulation by the PhoR-PhoB two-component regulatory system in E. coli.
Molecular and Ecological Analyses of Microbial Community Structures in Biofilms of a Full-Scale Aerated Up-Flow Biobead Process
Ju, Dong-Hun ; Choi, Min-Kyung ; Ahn, Jae-Hyung ; Kim, Mi-Hwa ; Cho, Jae-Chang ; Kim, Tae-Sung ; Kim, Tae-San ; Seong, Chi-Nam ; Ka, Jong-Ok ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 253~261
Molecular and cultivation techniques were used to characterize the bacterial communities of biobead reactor biofilms in a sewage treatment plant to which an Aerated Up-Flow Biobead process was applied. With this biobead process, the monthly average values of various chemical parameters in the effluent were generally kept under the regulation limits of the effluent quality of the sewage treatment plant during the operation period. Most probable number (MPN) analysis revealed that the population of denitrifying bacteria was abundant in the biobead #1 reactor, denitrifying and nitrifying bacteria coexisted in the biobead #2 reactor, and nitrifying bacteria prevailed over denitrifying bacteria in the biobead #3 reactor. The results of the MPN test suggested that the biobead #2 reactor was a transition zone leading to acclimated nitrifying biofilms in the biobead #3 reactor. Phylogenetic analysis of 16S rDNA sequences cloned from biofilms showed that the biobead #1 reactor, which received a high organic loading rate, had much diverse microorganisms, whereas the biobead #2 and #3 reactors were dominated by the members of Proteobacteria. DGGE analysis with the ammonia monooxygenase (amoA) gene supported the observation from the MPN test that the biofilms of September were fully developed and specialized for nitrification in the biobead reactor #3. All of the DNA sequences of the amoA DGGE bands were very similar to the sequence of the amoA gene of Nitrosomonas species, the presence of which is typical in the biological aerated filters. The results of this study showed that organic and inorganic nutrients were efficiently removed by both denitrifying microbial populations in the anaerobic tank and heterotrophic and nitrifying bacterial biofilms well-formed in the three functional biobead reactors in the Aerated Up-Flow Biobead process.
Detection and Characterization of a Lytic Pediococcus Bacteriophage from the Fermenting Cucumber Brine
Yoon, Sung-Sik ; Baprangou-Poueys Roudolphe ; Jr Fred Breidt ; Fleming Henry P. ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 262~270
Of the twelve lytic bacteriophages recovered from five different fermenting cucumber tanks that were inoculated with Pediococcus sp. LA0281, a lytic phage,
, was characterized in the present study. The plaques were mostly clear and round-shaped on the lawn of starter strain, indicating lytic phage. Overall appearance indicated that it belongs to the Siphoviridae family or Bradley's group B1, with a small isometric head and a flexible noncontractile tail with swollen base plate. The average size was found to be 51.2 nm in head diameter and 11.6 nm wide
129.6 nm long for the tail. The single-step growth kinetics curve showed that the eclipse and the latent period were 29 min and 34 min, respectively, and an average burst size was calculated to be 12 particles per infective center. The optimum proliferating temperature (
) was slightly lower than that of cell growth (
). The structural proteins revealed by SDS-PAGE consisted of one main protein of 33 kDa and three minor proteins of 85, 58, and 52 kDa. The phage genome was a linear double-stranded DNA without cohesive ends. Based on the single and double digestion patterns obtained by EcoRI, HindIII, and SalI, the physical map was constructed. The overall size of the phage genome was estimated to be 24.1 kb. The present report describes the presence of a lytic phage active against a commercial starter culture Pediococcus sp. LA0281 in cucumber fermentation, and a preliminary study characterizes the phage on bacterial successions in the process of starter-added cucumber fermentation.
Black Rice (Oryza sativa L. var. japonica) Hydrolyzed Peptides Induce Expression of Hyaluronan Synthase 2 Gene in HaCaT Keratinocytes
Sim, Gwan-Sub ; Lee, Dong-Hwan ; Kim, Jin-Hwa ; An, Sung-Kwan ; Choe, Tae-Boo ; Kwon, Tae-Jong ; Pyo, Hyeong-Bae ; Lee, Bum-Chun ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 271~279
Black rice (Oryza sativa L. var. japonica) has been used in folk medicine in Asia. To understand the effects of black rice hydrolyzed peptides (BRP) from germinated black rice, we assessed the expression levels of about 20,000 transcripts in BRP-treated HaCaT keratinocytes using human 1A oligo microarray analysis. As a result, the BRP treatment showed a differential expression ratio of more than 2-fold: 745 were activated and 1,011 were repressed. One of the most interesting findings was a 2-fold increase in hyaluronan synthase 2 (HAS2) gene expression by BRP. Semiquantitative RT-PCR showed that BRP increased HAS2 mRNA in dose-dependent manners. ELISA showed that BRP effectively increased hyaluronan (HA) production in HaCaT keratinocytes.
A Two-Strain Mixture of Rhizobacteria Elicits Induction of Systemic Resistance Against Pseudomonas syringae and Cucumber Mosaic Virus Coupled to Promotion of Plant Growth on Arabidopsis thaliana
Ryu Choong-Min ; Murphy John F. ; Reddy M.S. ; Kloepper Joseph W. ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 280~286
We evaluated a commercial biopreparation of plant growth-promoting rhizobacteria (PGPR) strains Bacillus subtilis GB03 and B. amyloliquefaciens IN937a formulated with the carrier chitosan (Bio Yield) for its capacity to elicit growth promotion and induced systemic resistance against infection by Cucumber Mosaic Virus (CMV) and Pseudomonas syringae pv. tomato DC3000 in Arabidopsis thaliana. The biopreparation promoted plant growth of Arabidopsis hormonal mutants, which included auxin, gibberellic acid, ethylene, jasmonate, salicylic acid, and brassinosteroid insensitive lines as well as each wild-type. The biopreparation protected plants against CMV based on disease severity in wild-type plants. However, virus titre was not lower in control plants and those treated with biopreparation, suggesting that the biopreparation induced tolerance rather than resistance against CMV. Interestingly, the biopreparation induced resistance against CMV in NahG plants, as evidenced by both reduced disease severity and virus titer. The biopreparation also elicited induced resistance against P. syringae pv. tomato in the wild-type but not in NahG transgenic plants, which degrade endogenous salicylic acid, indicating the involvement of salicylic acid signaling. Our results indicate that some PGPR strains can elicit plant growth promotion by mechanisms that are different from known hormonal signaling pathways. In addition, the mechanism for elicitation of induced resistance by PGPR may be pathogen-dependent. Collectively, the two-Bacilli strain mixture can be utilized as a biological inoculant for both protection of plant against bacterial and viral pathogens and enhancement of plant growth.
Characterization of Paraplantaricin C7, a Novel Bacteriocin Produced by Lactobacillus paraplantarum C7 Isolated from Kimchi
Lee, Kwang-Hee ; Park, Jae-Yong ; Jeong, Seon-Ju ; Kwon, Gun-Hee ; Lee, Hyong-Joo ; Chang, Hae-Choon ; Chung, Dae-Kyun ; Lee, Jong-Hoon ; Kim, Jeong-Hwan ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 287~296
A Lactobacillus paraplantarum strain producing a bacteriocin was isolated from kimchi using the spot-on-the lawn method and named L. paraplantarum C7 . The bacteriocin, paraplantaricin C7, was found to inhibit certain Lactobacillus strains, including L. plantarum, L. pentosus, and L. delbrueckii subsp. lactis. It also inhibited Enterococcus faecalis, yet did not inhibit most of the other LAB (lactic acid bacteria) tested. The maximum level of paraplantaricin C7 activity was observed under the culture conditions of
and a constant pH of 4.5. Paraplantaricin C7 retained 90% of its activity after 10 min of treatment at
and remained stable within a pH range of 2-8. Based on a culture supernatant, paraplantaricin C7 was purified by DEAE-Sephacel column chromatography and
reverse-phase HPLC. SDS-PAGE and activity staining were then conducted using the purified paraplantaricin C7, and its molecular mass determined to be about 3,800 Da. The 28 N-terminal amino acids from the purified paraplantaricin C7 were determined, and the structural gene encoding paraplantaricin C7, ppnC7, was cloned by PCR using degenerate primers based on the N-terminal amino acid sequence. The nucleotide sequences for ppnC7 and other neighboring orfs exhibited a limited homology to the previously reported plantaricin operon genes. Paraplantaricin C7 is a novel type II bacteriocin containing a double glycine leader sequence.
Influence of Aeration During Propagation of Pitching Yeast on Fermentation and Beer Flavor
Cheong, Chul ; Wackerbauer, Karl ; Kang, Soon-Ah ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 297~304
The effect of yeast propagated at different aeration conditions on yeast physiology, fermentation ability, and beer quality was investigated using three strains of Saccharomyces cerevisiae. It was shown that yeast cells grown under continuous aeration conditions during propagation were almost two times higher as compared with discontinuous aeration conditions. The maximum of cell growth of all samples reached between 36 hand 48 h. The concentration of trehalose was increased under continuous aerated yeasts, whereas glycogen was decreased. It was also observed that the concentration of glycogen and trehalose in yeast cells had no direct effect on subsequent fermentation ability. The effect of yeast propagated under different aeration conditions on subsequent fermentation ability was different from yeast strains, in which the influence will be most pronounced at the first fermentation. Later, the yeasts might regain its original characteristics in the following fermentations. Generally, continuously propagated yeast had a positive effect on beer quality in subsequent fermentation. Hence, the concentration of aroma compounds obtained with yeast propagated under 6 1/h for 48 h aeration was lower than those grown under other aeration conditions in the bottom yeasts; in particular, the amounts of phenylethyl alcohol, ester, and fatty acids were decreased.
Differential Stringent Responses of Streptomyces coelicolor M600 to Starvation of Specific Nutrients
Ryu, Yong-Gu ; Kim, Eun-Sook ; Kim, Dae-Wi ; Kim, Sung-Keun ; Lee, Kye-Joon ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 305~312
This study focused on the involvement of the unusual nucleotide (p)ppGpp, a stringent factor, during the morphological and physiological differentiation of Streptomyces coelicolor. Two genes, relA and rshA, were disrupted to demonstrate the roles of the stringent factor in the differentiation. The intracellular concentration of (p)ppGpp in the wild-type (M600) and disrupted mutants was measured in relation to the intentional starvation of a specific nutrient, such as carbon, nitrogen, and phosphate or the in situ depletion of nutrients in a batch culture. As a result, it was found that the morphological characteristic of the
mutant was a bld phenotype forming condensed mycelia, whereas the
mutant grew fast-forming spores and straightforward mycelia. In both mutants, the production of actinorhodin (Act) was completely abolished, yet the undecylprodigiosin (Red) production was increased. Intracellular (p)ppGpp was detected in the
mutant in the case of limited phosphate, yet not with limited carbon or nitrogen sources. In contrast, (p)ppGpp was produced in the
mutant under limited carbon and nitrogen conditions. Therefore, (p)ppGpp in S. coelicolor was found to be selectively regulated by either the RelA or RshA protein, which was differentially expressed in response to the specific nutrient limitation. These results were also supported by the in situ ppGpp production during a batch culture. Furthermore, it is suggested that RelA and RshA are bifunctional proteins that possess the ability to both synthesize and hydrolyze (p)ppGpp.
Statistical Optimization of Medium Components for the Production of Biosurfactant by Bacillus licheniformis K51
Joshi Joshi ; Sanket Sanket ; Yadav Sanjay ; Nerurkar Anuradha ; Desai Anjana J. ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 313~319
The nutritional medium requirement for biosurfactant production by Bacillus licheniformis K51 was optimized. The important medium components, identified by the initial screening method of Plackett-Burman, were
, and Na-EDTA. Box-Behnken response surface methodology was applied to further optimize biosurfactant production. The optimal concentrations for higher production of biosurfactants were (g/l): glucose,
and Na-EDTA, 30.0. Using this statistical optimization method, the relative biosurfactant yield as critical micelle dilution (CMD) was increased from
, which is ten times higher than the non-optimized rich medium.
Hydrogen Sulfide Removal by Immobilized Thiobacillus novellas on
in a Fluidized Bed Reactor
Cha, Jin-Myung ; Shin, Hyun-Jae ; Roh, Sung-Hee ; Kim, Sun-Il ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 320~324
The removal of hydrogen sulfide (
) from aqueous media was investigated using Thiobacillus novellas cells immobilized on a
carrier (biosand). The optimal growth conditions for the bacterial strain were
and initial pH of 7.0. The main product of hydrogen sulfide oxidation by T. novellus was identified as the sulfate ion. A removal efficiency of 98% was maintained in the three-phase fluidized-bed reactor, whereas the efficiency was reduced to 90% for the two-phase fluidized-bed reactor and 68% for the two-phase reactor without cells. The maximum gas removal capacity for the system was 254 g
when the inlet
. Stable operation of the immobilized reactor was possible for 20 days with the inlet
concentration held to 1,100 ppm. The fluidized bed bioreactor appeared to be an effective means for controlling hydrogen sulfide emissions.
Identification and Functional Analysis of Vibrio vulnificus SmcR, a Novel Global Regulator
Lee, Jeojng-Hyun ; Rhee, Jee-Eun ; Park, U-Ryung ; Ju, Hyun-Mok ; Lee, Byung-Cheol ; Kim, Tae-Sung ; Jeong, Hye-Sook ; Choi, Sang-Ho ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 325~334
Recently, quorum sensing has been implicated as an important global regulator controlling the production of numerous virulence factors such as capsular polysaccharides in bacterial pathogens. The nucleotide and deduced amino acid sequences of smcR, a homolog of V. harveyi luxR identified from V. vulnificus ATCC29307, were analyzed. The amino acid sequence of SmcR from V. vulnificus was 72 to 92% similar to those of LuxR homologs from Vibrio spp. Functions of SmcR were assessed by the construction of an isogenic mutant, whose smcR gene was inactivated by allelic exchanges, and by evaluating its phenotype changes in vitro and in mice. The disruption of smcR resulted in a significant alteration in biofilm formation, in type of colony morphology, and in motility. When compared with the wild-type, the smcR mutant exhibited reduced survival under adverse conditions, such as acidic pH and hyperosmotic stress. The smcR mutant exhibited decreased cytotoxic activity toward INT 407 cells in vitro. Furthermore, the intraperitoneal
of the smcR mutant was approximately
times higher than that of parental wild-type. Therefore, it appears that SmcR is a novel global regulator, controlling numerous genes contributing to the pathogenesis as well as survival of V. vulnificus.
Qualitative and Quantitative Analysis of Genetically Modified Pepper
Song, Hee-Sung ; Kim, Jae-Hwan ; Kim, Dong-Hern ; Kim, Hae-Yeong ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 335~341
For the development of qualitative and quantitative PCR methods of genetically modified (GM) pepper developed in Korea, a capsanthin-capsorubin synthase (CCS) gene was used as the endogenous reference gene. The primer pair ccs-F/R amplifying the pepper endogenous gene gave rise to an amplicon of 102 bp. No amplified product was observed when DNA samples from 16 different plants were used as templates. The construct-specific primer pairs amplifying the junction region of the bar gene and Ti7 introduced in GM pepper gave rise to an amplicon of 182 bp. Quantitative PCR assay was performed using a TaqMan probe and a standard plasmid as a reference molecule, which contained both an endogenous and event-specific sequence. For the validation of this method, the test samples containing 0.1, 1, 3, 5, and 10% GM pepper were quantified.
Characterization of Site-Specific Recombination by the Integrase MJ1 from Enterococcal Bacteriophage
Park, Mi-Ok ; Lim, Ki-Hong ; Kim, Tae-Hyung ; Chang, Hyo-Ihl ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 342~347
integrase (MJ1) was previously shown to perform a site-specific recombination between a phage attachment site (attP) and a host attachment site (attB) in its host, Enterococcus faecalis, and also in a non-host bacterium, Escherichia coli. Here, we investigated biochemical features of MJ1 integrase. First, MJ1 integrase could perform in vitro recombination between attP and attB in the absence of additional factors. Second, MJ1 integrase interacted with att sites. Electrophoretic mobility shift assays and DNase I footprinting revealed that MJ1 integrase could efficiently bind to all the att sites and that MJ1 integrase recognized relatively short sequences (
) containing an overlapping region within attB and attP. These results demonstrate that MJ1 integrase indeed catalyzes an integrative recombination between attP and attB, the mechanism of which might be simple and unidirectional, as found in serine integrases.
Functions of Metallothionein Generating Interleukin-10-Producing Regulatory
Cells Potentiate Suppression of Collagen-Induced Arthritis
Huh, Sung-Jin ; Lee, Kyu-Heon ; Yun, Hye-Sun ; Paik, Doo-Jin ; Kim, Jung-Mogg ; Youn, Jee-Hee ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 348~358
Metallothionein, a cysteine-rich stress response protein that is naturally induced by a variety of immunologic stressors, has been shown to suppress autoimmune disorders through mechanisms not yet fully defined. In the present study, we examined the underlying mechanisms by which metallothionein might mediate such regulation of autoimmunity.
T cells from metallothionein-deficient mice differentiated to produce significantly less IL-10,
, and repressor of GATA, but more
and T-bet, when compared with those from wild-type mice. The levels of IL-4 and GATA-3 production were not different between the two groups of mice. Conversely, treatment with exogenous metallothionein during the priming phase drove
cells to differentiate into cells producing more IL-10 and
, but less
than untreated cells. Metallothionein-primed cells were hyporesponsive to restimulation, and suppressive to T cell proliferation in an IL-10-dependent manner. Lymphocytes from metallothionein-deficient mice displayed significantly elevated levels of AP-1 and JNK activities in response to stimulation compared with those from wild-type controls. Importantly, transgenic mice overexpressing metallothionein exhibited significantly reduced susceptibility to collagen-induced arthritis and enhanced IL-10 level in the serum, relative to their nontransgenic littermates. Taken together, these data suggest that metallothionein is able to promote the generation of IL-10-and
-producing type 1 regulatory T-like cells by downregulating JNK-dependent AP-1 activity. Thus, metallothionein may play an important role in the regulation of Th1-dependent autoimmune arthritis, and may represent both a potential target for therapeutic manipulation and a critical element in the diagnostic assessment of disease potential.
Interaction Proteome Analysis of Xanthomonas Hrp Proteins
Jang, Mi ; Park, Byoung-Chul ; Lee, Do-Hee ; Bae, Kwang-Hee ; Cho, Sa-Yeon ; Park, Hyun-Seok ; Lee, Baek-Rak ; Park, Sung-Goo ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 359~363
Because of the importance of the type III protein-secretion system in bacteria-plant interaction, its function in bacterial pathogenesis of plants has been intensively studied. To identity bacterial proteins interacting with Xanthomonas hrp gene products that are involved in pathogenicity, we performed the glutathione-bead binding analysis of Xanthomonas lysates containing GST-tagged Hrp proteins. Analysis of glutathione-bead bound proteins by 1-DE and MALDI-TOF has demonstrated that Avr proteins, RecA, and several components of the type III secretion system interact with HrpB protein. This proteomic approach could provide a powerful tool in finding interaction partners of Hrp proteins whose roles in host-pathogen interaction need further studies.
Thermal Resistance and Inactivation of Enterobacter sakazakii Isolates during Rehydration of Powdered Infant Formula
Kim, Soo-Hwan ; Park, Jong-Hyun ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 364~368
Enterobacter sakazakii may be related to outbreaks of meningitis, septicemia, and necrotizing enterocolitis, mainly in neonates. To reduce the risk of E. sakazakii in baby foods, thermal characteristics for Korean E. sakazakii isolates were determined at 52, 56, and
in saline solution, rehydrated powdered infant formula, and dried baby food. In saline solution, their D-values were 12-16, 3-5, and 0.9-1 min for each temperature. D-values increased to 16-20, 4-5, and 2-4 min in rehydrated infant formula and 14-17, 5-6, and 2-3 min in dried baby food. The overall calculated z-value was 6-8 for saline, 8-10 for powdered infant formula, and 9-11 for dried baby food. Thermal inactivation of E. sakazakii during rehydration of powdered infant formula was investigated by viable counts. Inactivation of cultured E. sakazakii in infant formula milk did not occur for 20 min at room temperature after rehydration with the water at
and their counts were reduced by about 1-2 log CFU/g at
and 4-6 log CFU/ml with the water at 65 and
. However, the thermo stability of adapted E. sakazakii to the powdered infant formula increased more than two times. Considering that the levels of E. sakzakii observed in powdered infant formula have generally been 1 CFU/100 g of dry formula or less, contamination with E. sakazakii can be reduced or eliminated by rehydrating water with at least
higher temperature than the manufacturer-recommended
Crystallization and Preliminary X-Ray Diffraction Analysis of BcOMT2 from Bacillus cereus: A Family of O-Methyltransferase
Cho, Jang-Hee ; Lim, Yoong-Ho ; Ahn, Joong-Hoon ; Rhee, Sang-Kee ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 369~372
O-Methyltransferases (OMTs), one of the ubiquitous enzymes in plants, bacteria, and humans, catalyze a methyl-transfer reaction using S-adenosylmethionine and a wide range of phenolics as a methyl donor and acceptor, respectively. Substrates for most bacterial OMTs have largely remained elusive, but recent investigation using BcOMT2, an OMT from Bacillus cereus, suggested that ortho-dihydroxyflavonoids could serve as substrates. To elucidate the functional and structural features of BcOMT2, we expressed, and purified BcOMT2, and crystallized an apoenzyme and its ternary complex in the presence of a flavonoid and S-adenosylhomocysteine. Each crystal diffracted to
with its space group of C2 and
, respectively. Structural analysis of apo-BcOMT2 and its ternary complex will provide the structural basis of methyl transfer onto (iso)flavonoids in a regiospecific manner.
Phosphatidylcholine is Required for the Efficient Formation of Photosynthetic Membrane and B800-850 Light-Harvesting Complex in Rhodobacter sphaeroides
Kim, Eui-Jin ; Kim, Mi-Sun ; Lee, Jeong-K. ;
Journal of Microbiology and Biotechnology, volume 17, issue 2, 2007, Pages 373~377
No phosphatidylcholine (PC) was detected in the membrane of Rhodobacter sphaeroides pmtA mutant (PmtAl) lacking phosphatidylethanolamine (PE) N-methyltransferase, whereas PE in the mutant was increased up to the mole % comparable to the combined level of PE and PC of wild type. Neither the fatty acid composition nor the fluidity of membrane was altered by pmtA mutation. Consistently, aerobic and photoheterotrophic growth of PmtAl were not different from wild type. However, PmtAl showed an extended lag phase (15 h) after the growth transition from aerobic to photoheterotrophic conditions, indicating the PC requirement for the efficient formation of intracytoplasmic membrane (ICM). Interestingly, the B800-850 complex of PmtAl was decreased more than twofold in comparison with wild type, whereas the level of the B875 complex comprising the fixed photosynthetic unit was not changed. Since puc expression is not affected by pmtA mutation, PC appears to be required for the proper formation of the B800-850 complex in the ICM of R. sphaeroides.