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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 16, Issue 12 - Dec 2006
Volume 16, Issue 11 - Nov 2006
Volume 16, Issue 10 - Oct 2006
Volume 16, Issue 9 - Sep 2006
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Volume 16, Issue 6 - Jun 2006
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Secondary Carotenoid Accumulation in Haematococcus (Chlorophyceae): Biosynthesis, Regulation, and Biotechnology
Jin Eon-Seon ; Lee Choul-Gyun ; Polle Jurgen E.W. ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 821~831
Unicellular green algae of the genus Haematococcus have been studied extensively as model organisms for secondary carotenoid accumulation. Upon environmental stress, such as strong irradiance or nitrogen deficiency, unicellular green algae of the genus Haematococcus accumulate secondary carotenoids in vesicles in the cytosol. Because secondary carotenoid accumulation occurs only upon specific environmental stimuli, there is speculation about the regulation of the biosynthetic pathway specific for secondary carotenogenesis. Because the carotenoid biosynthesis pathway is located both in the chloroplast and the cytosol, communication between both cellular compartments must be considered. Recently, the induction and regulation of astaxanthin biosynthesis in microalgae received considerable attention because of the increasing use of this secondary carotenoid as a source of pigmentation for fish aquaculture, as a component in cancer prevention, and as a free-radical quencher. This review summarizes the biosynthesis and regulation of the pathway, as well as the biotechnology of astaxanthin production in Haematococcus.
Resources for Systems Biology Research
Kim Jin-Sik ; Yun Hong-Seok ; Kim Hyun-Uk ; Choi Hyung-Seok ; Kim Tae-Yong ; Woo Han-Min ; Lee Sang-Yup ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 832~848
Systems biology has recently become an important research paradigm that is anticipated to decipher the metabolic, regulatory, and signaling networks of complex living organisms on the whole organism level. Thus, various research outputs are being generated, along with the development of many tools and resources for systems biology research. Accordingly, this review provides a comprehensive summary of the current resources and tools for systems biology research that will hopefully be helpful to researchers involved in this field. The resources are categorized into the following five groups: genome information and analysis, transcriptome and proteome databases, metabolic profiling and metabolic control analysis, metabolic and regulatory information, and software for computational systems biology. A summary table and some future perspectives are also provided.
Influence of Extracellular Products from Haematococcus pluvialis on Growth and Bacteriocin Production by Three Species of Lactobacillus
Kim Jeong-Dong ; Lee Choul-Gyun ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 849~854
The effects of Haematococcus pluvialis extracellular products on microbial growth and bacteriocin production were investigated to improve bacteriocin synthesis during the growth cycle of Lactobacilli. Lactobacillus pentosus KJ-108, L. plantarum KJ-10311, and L. sakei KJ-2008 were cultured in MRS and enriched medium (ERM) with or without supplement of the extracellular products obtained from a late exponential phase culture of Haematococcus pluvialis in modified Bold's basal medium (MBBM). In both MRS and ERM, the extracellular products strongly enhanced the growth as well as the bacteriocin production of all the lactic acid bacteria tested. The enhancing effect was observed in ERM with pH adjusted at 5 and 6. In addition, some difference in growth effects with the extracellular products of H. pluvialis was observed between pH 5 and 6 in ERM, but no effect was observed in the minimal medium. The final biomass and the final concentration of bacteriocin activity were associated with the cell growth that was promoted by the extracellular products of H. pluvialis, and the enhanced cell growth of the three lactic acid bacterial strains induced the increase of the specific bacteriocin production. Therefore, bacteriocin production and activity were influenced by the addition of the extracellular products of H. pluvialis in the culture medium.
Membrane-Associated Hexavalent Chromium Reductase of Bacillus megaterium TKW3 with Induced Expression
Cheung K.H. ; Lai H.Y. ; Gu Ji-Dong ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 855~862
Hexavalent chromium (
) is a highly harmful pollutant, which can be detoxified and precipitated through reduction to
. Bacillus megaterium TKW3 previously isolated from chromium-contaminated marine sediments was capable of reducing
in concomitance with metalloids (
). Notwithstanding approximately 50% inhibition, it was the first report of simultaneous bacterial reduction of
(to elemental Se). No significant difference was observed among electron donors (glucose, maltose, and mannitol) on
reduction by B. megaterium TKW3. The reduction was constitutive and determined to be non-plasmid mediated. Peptide mass fingerprints (PMF) revealed a novel aerobic membrane-associated reductase with
-induced expression and specific reductive activity (in nmol
/mg protein/min) of 0.220 as compared with 0.087 of the soluble protein fraction. Respiratory inhibitor
did not interfere with the reductase activity. Transmission electron microscopy with energy dispersive X-ray (TEM-EDX) analysis confirmed the aggregation of reduced chromium along the intracellular membrane region. Future identification of the N-terminal amino acid sequence of this reductase will facilitate purification and understanding of its enzymatic action.
Flux Optimization Using Genetic Algorithms in Membrane Bioreactor
Kim Jung-Mo ; Park Chul-Hwan ; Kim Seung-Wook ; Kim Sang-Yong ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 863~869
The behavior of submerged membrane bioreactor (SMBR) filtration systems utilizing rapid air backpulsing as a cleaning technique to remove reversible foulants was investigated using a genetic algorithm (GA). A customized genetic algorithm with suitable genetic operators was used to generate optimal time profiles. From experiments utilizing short and long periods of forward and reverse filtration, various experimental process parameters were determined. The GA indicated that the optimal values for the net flux fell between 263-270 LMH when the forward filtration time (
) was 30-37 s and the backward filtration time (
) was 0.19-0.27 s. The experimental data confirmed the optimal backpulse duration and frequency that maximized the net flux, which represented a four-fold improvement in 24-h backpulsing experiments compared with the absence of backpulsing. Consequently, the identification of a region of feasible parameters and nonlinear flux optimization were both successfully performed by the genetic algorithm, meaning the genetic algorithm-based optimization proved to be useful for solving SMBR flux optimization problems.
Formation of Succinic Acid by Klebsiella pneumoniae MCM B-325 Under Aerobic and Anaerobic Conditions
Thakker Chandresh ; Bhosale Suresh ; Ranade Dilip ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 870~879
The present study describes the formation of succinic acid by a nonvirulent, highly osmotolerant Klebsiella pneumoniae strain SAP (succinic acid producer), its profile of metabolites, and enzymes of the succinate production pathway. The strain produced succinate along with other metabolites such as lactate, acetate, and ethanol under aerobic as well as anaerobic growth conditions. The yield of succinate was higher in the presence of
atmosphere as compared with that under
atmosphere. Analysis of intracellular metabolites showed the presence of a smaller PEP pool than that of pyruvate. Oxaloacetate, citrate, and
-ketoglutarate pools were considerably larger than those of isocitrate and fumarate. In order to understand the synthesis of succinate, the enzymes involved in end-product formation were studied. Levels of phosphoenolpyruvate carboxykinase, fumarate reductase, pyruvate kinase, and acetate kinase were higher under anaerobic growth conditions. Based on the profiles of the metabolites and enzymes, it was concluded that the synthesis of succinate took place via oxaloacetate, malate, and fumarate in the strain under anaerobic growth conditions. The strain SAP showed potential for the bioconversion of fumarate to succinate under
atmosphere in the presence of
. At an initial fumarate concentration of 10 g/l, 7.1 g/l fumarate was converted to 7 g/l succinate with a molar conversion efficiency of 97.3%. The conversion efficiency and succinate yield were increased in the presence of glucose. Cells grown on fumarate contained an 18-fold higher fumarate reductase activity as compared with the activity obtained when grown on glucose.
Structure and Bacterial Cell Selectivity of a Fish-Derived Antimicrobial Peptide, Pleurocidin
Yang Ji-Young ; Shin Song-Yub ; Lim Shin-Saeng ; Hahm Kyung-Soo ; Kim Yang-Mee ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 880~888
-helical cationic antimicrobial peptide, was isolated from skin mucosa of winter flounder (Pleuronectes americamus). It had strong antimicrobial activities against Gram-positive and Gram-negative bacteria, but had very weak hemolytic activity. The Gly
Ala analog (pleurocidin-AA) showed similar antibacterial activities, but had dramatically increased hemolytic activity. The bacterial cell selectivity of pleurocidin was confirmed through the membrane-disrupting and membrane-binding affinities using dye leakage, tryptophan fluorescence blue shift, and tryptophan quenching experiments. However, the non-cell-selective antimicrobial peptide, pleurocidin-AA, interacts strongly with both negatively charged and zwitterionic phospholipid membranes, the latter of which are the major constituents of the outer leaflet of erythrocytes. Circular dihroism spectra showed that pleurocidin-AA has much higher contents of
-helical conformation than pleurocidin. The tertiary structure determined by NMR spectroscopy showed that pleurocidin has a flexible. structure between the long helix from
and the short helix from
. Cell-selective antimicrobial peptide pleurocidin interacts strongly with negatively charged phospholipid membranes, which mimic bacterial membranes. Structural flexibility between the two helices may play a key role in bacterial cell selectivity of pleurocidin.
Characterization of Extended Spectrum
-Lactamase Genotype TEM, SHV, and CTX-M Producing Klebsiella pneumoniae Isolated from Clinical Specimens in Korea
Kim Yun-Tae ; Kim Tae-Un ; Baik Hyung-Suk ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 889~895
To investigate the antibiotic-resistant patterns and the gene types of extended-spectrum
-lactamase (ESBL)-producing Klebsiella pneumoniae, we collected 226 Klebsiella pneumoniae strains from three general hospitals with more than 500 beds in Busan, Korea from September 2004 to October 2005, The minimum inhibitory concentration (MIC) of antibiotics was measured using the Gram-negative susceptibility (GNS) cards of Vitek (Vitek system, Hazelwood Inc., MO, U.S.A.). Of the 226 K, pneumoniae isolates, 65 ESBL-producing K. pneumoniae strains were detected by the Vitek system and confirmed by the double-disk synergy test. TEM (Temoniera) type, SHV (sulfhydryl variable) type, and CTX-M (cefotaxime) type genes were detected by polymerase chain reaction. All 65 K. pneumoniae strains were resistant to ampicillin, cefazolin, cefepime, ceftriaxone, and aztreonam, and 83.0% of the organisms were resistant to ampicillin/sulbactam, 66.1% to tobramycin, 67.6% to piperacillin/tazobactam, 61.5% to ciprofloxacin, and 47.6% to trimethoprim/sulfamethoxazole, and 43.0% to gentamicin. TEM-type ESBLs (TEM-1 type, -52 type) were found in 64.6% (42 of 65) of the isolates, SHV-type ESBLs (SHV-2a type, -12 type, -28 type) in 70.7% (46 of 65) of isolates, and CTX-M-type ESBLS (CTX-M-15 type) in 45% (29 of 65) of isolates. Of the 65 ESBL-producing K. pneumoniae strains, two strains were found to harbor blaSHV-28, which were detected in Korea for the first time. Therefore, more investigation and research on SHV-28 are needed in order to prevent the ESBL type-producing K. pneumoniae from spreading resistance to oxyimino cephalosporin antibiotics.
Novel Function of Cytokinin: A Signaling Molecule for Promotion of Antibiotic Production in Streptomycetes
Yang Young-Yell ; Zhao Xin-Qing ; Jin Ying-Yu ; Huh Jung-Hyun ; Cheng Jin-Hua ; Singh Deepak ; Kwon Hyung-Jin ; Suh Joo-Won ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 896~900
Cytokinin has been known to act as a plant hormone to promote cell division and function in diverse processes in plant growth and development. Besides being produced in plants, it is also produced by various bacteria and fungi; however, its ecological significance is still unclear. In this report, we present an interesting finding that transzeatin riboside (tZR), a naturally occurring cytokinin compound, increased antibiotic production in many different streptomycetes, including Streptomyces coelicolor Ml3O, S. pristinaespiralis ATCC 25486, S. violaceoruber Tu22, S. anfibioticus ATCC l1891, and S. griseus IFO 13350. In vitro plate assays showed that the addition of 100
M tZR increased the growth inhibition of Pseudomonas syringae pv. syringae, a plant pathogen, by S. griseus, a streptomycin producer. We suggest that cytokinin could act as a signaling molecule for antibiotic production in streptomycetes, a group of rhizosphere bacteria.
Analysis of Poly(3-Hydroxybutyrate) Granule-Associated Proteome in Recombinant Escherichia coli
Han Mee-Jung ; Park Si-Jae ; Lee Jeong-Wook ; Min Byoung-Hoon ; Lee Sang-Yup ; Kim Soo-Jin ; Yoo Jong-Shin ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 901~910
Poly(3-hydroxybutyrate) [P(3HB)] is a microbial polyester intracellularly accumulated as distinct granules in numerous microorganisms as an energy and carbon storage material. Recombinant Escherichia coli harboring the heterologous P(3HB) biosynthesis genes accumulates large amounts of P(3HB) granules, yet the granule-associated proteins have not been identified. Therefore, this study reports on an analysis of the P(3HB) granule-associated proteome in recombinant E. coli. Fiye proteins out of 7 spots identified were found to be involved in functions of translation, heat-stress responses, and P(3HB) biosynthesis. Two of the major granule-associated proteins, IbpA/B, which are already known to bind to recombinant proteins forming inclusion bodies in E. coli, were further analyzed. Immunoblotting and immunoelectron microscopic studies with IbpA/B antibodies clearly demonstrated the binding and localization of IbpA/B to P(3HB) granules. IbpA/B seemed to play an important role in recombinant E. coli producing P(3HB) by stabilizing the interface between the hydrophobic P(3HB) granules and the hydrophilic cytoplasm. Thus, IbpA/B were found to act like phasins in recombinant E. coli, as they are the major proteins bound to the P(3HB) granules, affect the morphology of the granules, and reduce the amount of cytosolic proteins bound to the P(3HB) granules.
Proteomic Analysis of Resting and Activated Human
Koo Jung-Hui ; Chae Wook-Jun ; Choi Je-Min ; Nam Hyung-Wook ; Morio Tomohiro ; Kim Yu-Sam ; Jang Yang-Soo ; Choi Kwan-Yong ; Yang Jung-Jin ; Lee Sang-Kyou ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 911~920
] T Iymphocytes with the cytotoxic activity and capability to release various cytokines are the major players in immune responses against viral infection and cancer. To identify the proteins specific to resting or activated human CD8
T cells, human CD8
T cells were activated with anti-CD3+anti-CD28 mAb in the presence of IL-2. The solubilized proteins from resting and activated human CD8
T cells were separated by high-resolution two-dimensional polyacrylamide gel electrophoresis, and their proteomes were analyzed. Proteomic analysis of resting and activated T cells resulted in identification of 35 proteins with the altered expression. Mass spectrometry coupled with Profound and SWISS-PROT database analysis revealed that these identified proteins are to be functionally associated with cell proliferation, metabolic pathways, antigen presentation, and intracellular signal transduction pathways. We also identified six unknown proteins predicted from genomic DNA sequences specific to resting or activated CD8
T cells. Protein network studies and functional characterization of these novel proteins may provide new insight into the signaling transduction pathway of CD8
T cell activation.
Production and Location of Xylanolytic Enzymes in Alkaliphilic Bacillus sp. K-1
Lee Yun-Sik ; Ratanakhanokchai Khanok ; Piyatheerawong Weela ; Kyu Khin-Lay ; Rho Min-Suk ; Kim Yong-Seok ; Om Aeson ; Lee Joo-Won ; Jhee Ok-Hwa ; Chon Gil-Hyung ; Park Hyun ; Kang Ju-Seop ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 921~926
The production and location of xylanolytic enzymes in alkaliphilic Bacillus sp. K-1, isolated from the wastewater treatment plant of the pulp and paper industry, was studied. When grown in alkaline xylan medium, the bacteria produced xylanolytic enzymes such as xylanase,
-xylosidase, arabinofuranosidase, and acetyl esterase. Two types of xylanases (23 and 45 kDa) were found to be extracellular, but another type of xylanase (35 and/or 40 kDa) was detected as pellet-bound that was eluted with 2% triethylamine from the residual xylan of the culture. The xylanases were different in their molecular weight and xylan-binding ability. Arabinofuranosidase and
-xylosidase were found to be intracellular and extracellular, respectively, and acetyl esterase was found to be extracellular. The extracellular xylanolytic enzymes effectively hydrolyzed insoluble xylan, lignocellulosic materials, and xylans in kraft pulps.
S-Adenosylmethionine (SAM) Regulates Antibiotic Biosynthesis in Streptomyces spp. in a Mode Independent of Its Role as a Methyl Donor
Zhao Xin-Qing ; Jin Ying-Yu ; Kwon Hyung-Jin ; Yang Young-Yell ; Suh Joo-Won ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 927~932
S-Adenosylmethionine (SAM) is a ubiquitous biomolecule serving mainly as a methyl donor. Our recent studies revealed that SAM controls antibiotic production in Streptomyces. In this study, the functional mode of SAM was studied in S. coelicolor and S. antibioticus ATCC11891, employing S-adenosylhomocysteine (SAH), a methylation reaction product of SAM. Actinorhodin biosynthesis did not require SAM as a methyl donor, whereas SAH enhanced the actinorhodin biosynthesis up to the level comparable to SAM, and the most effective concentration of SAH was higher than that of SAM. In the case of oleandomycin that requires SAM for its biosynthesis, both SAM and SAH at the concentration as low as 100 mM showed comparable efficacy in enhancing the production; SAM at 1 mM concentration additionally stimulated to give a 5-fold enhancement of oleandomycin production. In vitro autophosphorylation of protein kinase AfsK was found to be activated by both SAM and SAH, as well as other structurally related compounds. Our studies demonstrate that SAM regulates antibiotic biosynthesis in a mode independent of its role as a methyl donor and suggest that SAM acts directly as an intracellular signaling molecule for Streptomyces.
Production of Coenzyme
by Recombinant E. coli Harboring the Decaprenyl Diphosphate Synthase Gene from Sinorhizobium meliloti
Seo Myung-Ji ; Im Eun-Mi ; Hur Jin-Haeng ; Nam Jung-Yeon ; Hyun Chang-Gu ; Pyun Yu-Ryang ; Kim Soon-Ok ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 933~938
Decaprenyl diphosphate synthase (DPS) is the key enzyme for the production of coenzyme
). A dps gene from Sinorhizobium meliioti KCCM 11232 (IFO 14782) was isolated by PCR and then cloned in Escherichia coli. DNA sequencing analysis revealed an open reading frame of 1,017 bp encoding a 338-amino-acid protein. The protein was identical at the 98% level to the putative octaprenyl diphosphate synthase (IspB) of S. meliloti 1021. The deduced amino acid sequence included the DDxxD domains conserved in the majority of the prenyl diphosphate synthases. Heterologous expression in E. coli BL21 (DE3) was carried out, and the
produced was then analyzed by HPLC. E. coli BL21 (DE3) harboring the dps gene from S. melioti produced CoQ
in addition to endogenous coenzyme Q
), whereas wild-type E. coli BL21 (DE3) host did not have the ability of producing CoQ
. The results suggest that the putative dps from S. meliloti KCTC 2353 encoded the DPS.
Function of Cell-Bound and Released Exopolysaccharides Produced by Lactobacillus rhamnosus ATCC 9595
Kim Ji-Uk ; Kim Young-Hoon ; Han Kyoung-Sik ; Oh Se-Jong ; Whang Kwang-Youn ; Kim Jai-Neung ; Kim Sae-Hun ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 939~945
The physiological characteristics and function of the exopolysaccharide (EPS) produced by Lactobacillus rhamnosus ATCC 9595 were determined. The total quantity of EPS was rapidly increased to 496
20 mg/l during the exponential phase, and then maintained steadily during the stationary phase. During the exponential phase (18 h), the total EPS consisted of 61% cell-bound EPS (cb-EPS) and 39% released EPS (r-EPS), whereas the relative proportion of EPS during the stationary phase (48 h) was convered to 23% cb-EPS and 77% r-EPS. On gel permeation chromatography, cb-EPS was fractionated as a single peak of 8.6
Da, whereas r-EPS was fractionated as two peaks with average molecular weights of 4.3
Da. Interestingly, both EPS species exhibited anticancer properties and cholera toxin-binding activities. Our results suggest that the EPS generated by L. rhamnosus ATCC 9595 might be suitable for use as a functional food or food supplement.
Identification of Proteins Affected by Iron in Saccharomyces cerevisiae Using Proteome Analysis
Lieu Hae-Youn ; Song Hyung-Seok ; Yang Seung-Nam ; Kim Jae-Hwan ; Kim Hyun-Joong ; Park Young-Doo ; Park Cheon-Seok ; Kim Hae-Yeong ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 946~951
To study the effect of iron on Saccharomyces cerevisiae, whole-cell proteins of Saccharomyces cerevisiae were extracted and subjected to two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and differentially expressed proteins were identified. The proteins separated were further identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and were compared with a protein database. Of more than 300 spots separated by molecular weight and isoelectric points, 27 differentially expressed spots were identified. Ten proteins were found to be differentially expressed at high iron concentration. Triosephosphate isomerase (TPI), YDR533C hypothetical protein, superoxide dismutase (SOD), 60 kDa heat-shock protein (HSP60), pyruvate dehydrogenase beta subunit 1 (PDB1), and old yellow enzyme 2 (OYE2) were upregulated, whereas thiol-specific antioxidant (TSA), regulatory particle non-ATPase subunit 8 (RPN8), thiol-specific peroxiredoxin 1 (AHP1), and fructose-1, 6-bisphosphate adolase (FBA) were downregulated by iron. Based on the result, we propose that SOD upregulated by iron would protect the yeast from oxidative stress by iron, and that TSA downregulated by iron would render cells hypersensitive to oxidative stress.
Activity of Early Gene Promoters from a Korean Chlorella Virus Isolate in Transformed Chlorella Algae
Jung Heoy-Kyung ; Kim Gun-Do ; Choi Tae-Jin ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 952~960
As a unicellular green alga that possesses many of the metabolic pathways present in higher plants, Chlorelia offers many advantages for expression of heterologous proteins. Since strong and constitutive promoters are necessary for efficient expression in heterologous expression systems, the development of such promoters for use in the Chlorella system was the aim of this study. Proteins encoded by the early genes of algal viruses are expressed before viral replication, probably by the host transcriptional machinery, and the promoters of these genes might be useful for heterologous expression in Chlorella. In this study, putative promoter regions of DNA polymerase, ATP-dependent DNA ligase, and chitinase genes were amplified from eight Korean Chlorella virus isolates by using primer sets designed based on the sequence of the genome of PBCV-1, the prototype of the Phycodnaviridae. These putative promoter regions were found to contain several cis-acting elements for transcription factors, including the TATA, CAAT, NTBBF1, GATA, and CCAAT boxes. The amplified promoter regions were placed into Chlorella transformation vectors containing a green fluorescence protein (GFP) reporter gene and the Sh ble gene for phleomycin resistance. C. vulgaris protoplasts were transformed and then selected with phleomycin. The GFP fluorescence intensities of cells transformed with chitinase, DNA polymerase, and DNA ligase gene promoter-GFP fusion constructs were 101.5, 100.8, and 95.8%, respectively, of that of CaMV 35S-GFP-transformed Chlorella cells. These results demonstrate that these viral promoters are active in transformed Chlorella.
Overproduction of Cellulose in Acetobacter xylinum KCCM 10100 Defective in GDP-Mannosyltransferase
Park Sang-Tae ; Kim Eung-Bin ; Kim Young-Min ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 961~964
GDP-mannosyltransferase (GMT) is an enzyme responsible for the addition of a mannose to glucose (
3]) during biosynthesis of the water-soluble branched polysaccharide acetan in Acefobacter species. In an effort to obtain a cellulose-overproducing bacterium, a mutant defective in GMT of Acetobacter xylinum KCCM 10100 was constructed by single crossover homologous recombination using part of the aceA gene encoding GMT amplified by polymerase chain reaction. The GMT-disrupted mutant produced 23% more cellulose, but 16% less water-soluble polysaccharide than those of the wild-type strain. Analysis of the sugar composition by gel permeation chromatography revealed that water-soluble polysaccharides produced by the GMT-defective mutant contained no mannose molecule.
AdoMet Derivatives Induce the Production of Actinorhodin in Streptomyces coelicolor
Lee Yu-Kyung ; Young Jung-Mo ; Kwon Hyung-Jin ; Suh Joo-Won ; Kim Jin-Young ; Chong You-Hoon ; Lim Yoong-Ho ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 965~968
Exogenous S-adenosyl-L-methionine (AdoMet) enhances the production of actinorhodin in Streptomyces coelicolor. Thirty compounds related structurally with AdoMet were tested for their actinorhodin production. The relationships between the structures of the compounds tested and their actinorhodin production were analyzed using computational methods, and the molecules containing both bulky substituents at the C6 position of adenine and the long 5'-alkyl chain of adenosine were predicted to show high actinorhodin production.
Effects of Intermediate Metabolites on Phenanthrene Biodegradation
Cho Hwa-Young ; Woo Seung-Han ; Park Jong-Moon ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 969~973
Stimulatory effects of three different intermediate metabolites (1-hydroxy-2-naphthoate, salicylate, and catechol) as potential inducers on phenanthrene degradation were investigated using two different bacteria (Pseudomonas putida ATCC 17484 and Burkholderia cepacia PB12). The relative induction capacity was high in the sequence of 1-hydroxy-2-naphthoate, salicylate, and catechol in both strains. The highest of up to 12 times increase of the induction was obtained by the addition of 1-hydroxy-2-naphthoate in the strain PB12, compared with the control where no exogenous inducer was added. The induction capacity of the potential inducers was closely related with the number of oxygenations required per electron equivalents in one mole of the inducer.
Hydroxylation of Indole by PikC Cytochrome P450 from Streptomyces venezuelae and Engineering Its Catalytic Activity by Site-Directed Mutagenesis
Lee Sang-Kil ; Park Je-Won ; Park Sung-Ryeol ; Ahn Jong-Seog ; Choi Cha-Yong ; Yoon Yeo-Joon ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 974~978
The cytochrome P450 monooxygenase from the pikromycin biosynthetic gene cluster in Streptomyces venezuelae, known as PikC, was observed to hydroxylate the unnatural substrate indole to indigo. Furthermore, the site-directed mutagenesis of PikC monooxygenase led to the mutant enzyme F171Q, in which Phe171 was altered to Gln, with enhanced activity for the hydroxylation of indole. From enzyme kinetic studies, F171Q showed an approximately five-fold higher catalytic efficiency compared with the wild-type PikC. Therefore, these results demonstrate the promising application of P450s originating from Streptomyces, normally involved in polyketide biosynthesis, to generate a diverse array of other industrially useful compounds.
Development of Reusable Split URA3-Marked Knockout Vectors for Saccharomyces cerevisiae
Lee Tae-Hee ; Kim Myoung-Dong ; Seo Jin-Ho ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 979~982
Two knockout vectors, in which the truncated Kluyveromyces lactis URAS gene is flanked by a direct repeat, were developed for Saccharomyces cerevisiae. Each vector was designed to harbor 5'- and 3'-end homology regions for integration. Two knockout fragments were devised to integrate into the correct locus in a complementary manner to disrupt a gene of interest and. concomitantly to make functional Kl URA3 for transfomant selection. The use of dual complementary knockout cassettes was expected to dramatically reduce integration into unwanted loci in the genome. The knockout system developed in this study was successfully used for disruption of the GAL1 gene in S. cerevisiae.
Treatment with Glucanhydrolase from Lipomyces starkeyi for Removal of Soluble Polysaccharides in Sugar Processing
Lee Jin-Ha ; Kim Gha-Hyun ; Kim Seung-Heuk ; Cho Dong-Lyun ; Kim Do-Won ; Day Donal F. ; Kim Do-Man ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 983~987
The sole use of the glucanhydrolase (exhibiting both dextranase and amylase activities) from Lipomyces starkeyi hydrolyzed the soluble polysaccharides in sugar syrup more efficiently than a mixed treatment using both commercial dextranase and amylase. The glucanhydrolase treatment of stale sugar cane juice resulted in a yield of square, light-colored sugar crystals.
Characterization of ptsHI Operon from Leuconostoc mesenteroides SY1, a Strain Isolated from Kimchi
Park Jae-Yong ; Jeong Seon-Ju ; Chun Ji-Yeon ; Lee Jong-Hoon ; Chung Dae-Kyun ; Kim Jeong-Hwan ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 988~992
The ptsHI operon from Leuconostoc mesenteroides ssp. mesenteroides SY1 (L. mesenteroides SY1), a strain isolated from kimchi, was cloned and characterized. The ptsH open reading frame (ORF) was 273 bp in size, which can encode a protein of 90 amino acid residues with a molecular weight of 9,212 Da. The pfsI ORF was 1,719 bp in size, which was capable of encoding a protein of 572 amino acids with a molecular mass of 62,549 Da. ptsH and pfsI genes were transcribed as a single transcript of 2.0 kb in size regardless of carbon sources, supporting the operon structure. Although the deduced amino acid sequences of the HPr and EI were highly homologous with those of other Gram-positive bacteria, an additional amino acid (glutamine at the
amino acid) was present in HPr from L. mesenteroides SY1. Phosphorylation sites of HPr included the histidine residue (
) and serine residue (
). Mutant HPrs, in which each phosphorylation site was mutated into alanine, were obtained, and phosphorylation with HPr and mutated HPrs showed that HPr was phosphorylated at the serine residue (
) by HPr kinaseiphosphorylase (HPr K/P).
Simulation of Dynamic Behavior of Glucose- and Tryptophan-Grown Escherichia coli Using Constraint-Based Metabolic Models with a Hierarchical Regulatory Network
Lee Sung-Gun ; Kim Yu-Jin ; Han Sang-Il ; Oh You-Kwan ; Park Sung-Hoon ; Kim Young-Han ; Hwang Kyu-Suk ;
Journal of Microbiology and Biotechnology, volume 16, issue 6, 2006, Pages 993~998
We earlier suggested a hierarchical regulatory network using defined modeling symbols and weights in order to improve the flux balance analysis (FBA) with regulatory events that were represented by if-then rules and Boolean logic. In the present study, the simulation results of the models, which were developed and improved from the previou model by incorporating a hierarchical regulatory network into the FBA, were compared with the experimental outcome of an aerobic batch growth of E. coli on glucose and tryptophan. From the experimental result, a diauxic growth curve was observed, reflecting growth resumption, when tryptophan was used as an alternativee after the supply of glucose was exhausted. The model parameters, the initial concentration of substrates (0.92 mM glucose and 1 mM tryptophan), cell density (0.0086 g biomass/1), the maximal uptake rates of substrates (5.4 mmol glucose/g DCW h and 1.32 mmol tryptophan/g DCW h), and lag time (0.32 h) were derived from the experimental data for more accurate prediction. The simulation results agreed with the experimental outcome of the temporal profiles of cell density and glucose, and tryptophan concentrations.