Journal of Microbiology

Volume 44(5); October 2006

Research Support, Non-U.S. Gov'ts

Evidence of Indigenous NAH Plasmid of Naphthalene Degrading Pseudomonas putida PpG7 Strain Implicated in Limonin Degradation: Moushumi Ghosh , Abhijit Ganguli , Meenakshi Mallik; J. Microbiol. 2006;44(5):473-479.; DOI: https://doi.org/2451 [pii]

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Abstract: A well characterized naphthalene-degrading strain, Pseudomonas putida PpG7 was observed to utilize limonin, a highly-oxygenated triterpenoid compound as a sole source of carbon and energy. Limonin concentrations evidenced a 64% reduction over 48 h of growth in batch cultures. Attempts were made to acquire a plasmid-less derivative via various methods (viz. Ethidium Bromide, SDS, elevated temperature & mitomycin C), among which the method involving mitomycin C (20 μg/ml) proved successful. Concomitant with the loss of plasmid in P. putida PpG7 strain, the cured derivative was identified as a lim- phenotype. The lim+ phenotype could be conjugally transferred to the cured derivative. Based on the results of curing with mitomycin C, conjugation studies and presence of ndo gene encoding naphthalene 1,2 dioxygenase, it was demonstrated that genes for the limonin utilization were encoded on an 83 kb indigenous transmissible Inc. P9 NAH plasmid in Pseudomonas putida PpG7 strain.

Lichen Flora around the Korean Antarctic Scientific Station, King George Island, Antarctic: Ji Hee Kim , In-Young Ahn , Soon Gyu Hong , Mikhail Andreev , Kwang-Mi Lim , Mi Jin Oh , Young Jin Koh , Jae-Seoun Hur; J. Microbiol. 2006;44(5):480-491.; DOI: https://doi.org/2450 [pii]

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Abstract: As part of the long-term monitoring projects on Antarctic terrestrial vegetation in relation to global climate change, a lichen floristical survey was conducted around the Korean Antarctic Station (King Sejong Station), which is located on Barton Peninsula, King George Island, in January and February of 2006. Two hundred and twenty-five lichen specimens were collected and sixty-two lichen species in 38 genera were identified by morphological characteristics, chemical constituents, TLC analysis and ITS nucleotide sequence analysis.

Heat Shock Causes Oxidative Stress and Induces a Variety of Cell Rescue Proteins in Saccharomyces cerevisiae KNU5377: Il-Sup Kim , Hye-Youn Moon , Hae-Sun Yun , Ingnyol Jin; J. Microbiol. 2006;44(5):492-501.; DOI: https://doi.org/2449 [pii]

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Abstract: In this study, we attempted to characterize the physiological response to oxidative stress by heat shock in Saccharomyces cerevisiae KNU5377 (KNU5377) that ferments at a temperature of 40°C. The KNU5377 strain evidenced a very similar growth rate at 40°C as was recorded under normal conditions. Unlike the laboratory strains of S. cerevisiae, the cell viability of KNU5377 was affected slightly under 2 hours of heat stress conditions at 43°C. KNU5377 evidenced a time-dependent increase in hydroperoxide levels, carbonyl contents, and malondialdehyde (MDA), which increased in the expression of a variety of cell rescue proteins containing Hsp104p, Ssap, Hsp30p, Sod1p, catalase, glutathione reductase, G6PDH, thioredoxin, thioredoxin peroxidase (Tsa1p), Adhp, Aldp, trehalose and glycogen at high temperature. Pma1/2p, Hsp90p and H+-ATPase expression levels were reduced as the result of exposure to heat shock. With regard to cellular fatty acid composition, levels of unsaturated fatty acids (USFAs) were increased significantly at high temperatures (43°C), and this was particularly true of oleic acid (C18:1). The results of this study indicated that oxidative stress as the result of heat shock may induce a more profound stimulation of trehalose, antioxidant enzymes, and heat shock proteins, as well as an increase in the USFAs ratios. This might contribute to cellular protective functions for the maintenance of cellular homeostasis, and may also contribute to membrane fluidity.

Journal Article

Effect of Mycelial Extract of Clavicorona pyxidata on Acetylcholinesterase and β-Secretase Activity in vitro: Tae-Hee Lee , Young-Il Park , Yeong-Hwan Han; J. Microbiol. 2006;44(5):502-507.; DOI: https://doi.org/2448 [pii]

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Abstract: In a previous study, an extract of Clavicorona pyxidata DGUM 29005 mycelia demonstrated an inhibitory effect against enzyme-associated perceptual disorders. We have attempted to determine whether this mycelial extract is also capable of inhibiting the activities of acetylcholinesterase (AChE) and β-secretase (BACE) activity. Butanol, ethanol, and water extracts of C. pyxidata DGUM 29005 mycelia were shown to inhibit AChE activity by 99.3%, 93.7%, and 91.7%, respectively. The inhibitory value of the butanol extract was more profound than that of tacrine (95.4%). The ethanol extract also exerted an inhibitory effect against BACE activity; this fraction may harbor the potential for development into a pharmocotherapeutic modality for the treatment of Alzheimer''s disease (AD) patients. Rat pheochromocytoma PC12 cells in culture were not determined to be susceptible to the cytotoxic activity evidenced by the mycelial extract. The ethanol extract inhibited endogenous AChE activity in PC12 cellular homogenates, with an IC50 of 67.5 μg/ml, after incubation with intact cells, and also inhibited BACE activity in a dose-dependent fashion. These results suggest that the C. pyxidata mycelial extract has the potential to enhance cholinergic function and, therefore, may perform a function in the amelioration of the cholinergic deficit observed in cases of AD, as well as other types of age-associated memory impairment.

Research Support, Non-U.S. Gov'ts

Analysis of Double Stranded DNA-dependent Activities of Deinococcus radiodurans RecA Protein: Jong-Il Kim; J. Microbiol. 2006;44(5):508-514.; DOI: https://doi.org/2447 [pii]

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Abstract: In this study, the double-stranded DNA-dependent activities of Deinococcus radiodurans RecA protein (Dr RecA) were characterized. The interactions of the Dr RecA protein with double-stranded DNA were determined, especially dsDNA-dependent ATP hydrolysis by the Dr RecA protein and the DNA strand exchange reaction, in which multiple branch points exist on a single RecA protein-DNA complex. A nucleotide cofactor (ATP or dATP ) was required for the Dr RecA protein binding to duplex DNA. In the presence of dATP, the nucleation step in the binding process occurred more rapidly than in the presence of ATP. Salts inhibited the binding of the Dr RecA protein to double-stranded DNA. Doublestranded DNA-dependent ATPase activities showed a different sensitivity to anion species. Glutamate had only a minimal effect on the double-stranded DNA-dependent ATPase activities, up to a concentration of 0.7 M. In the competition experiment for Dr RecA protein binding, the Dr RecA protein manifested a higher affinity to double-stranded DNA than was observed for single-stranded DNA.

Cloning and Sequence Analysis of a Glyceraldehyde-3-phosphate Dehydrogenase Gene from Ganoderma lucidum: Xu Fei , Ming Wen Zhao , Yu Xiang Li; J. Microbiol. 2006;44(5):515-522.; DOI: https://doi.org/2446 [pii]

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Abstract: A cDNA library of Ganoderma lucidum has been constructed using a Zap Express cloning vector. A glyceraldehyde-3-phosphate dehydrogenase gene (gpd) was isolated from this library by hybridization of the recombinant phage clones with a gpd-specific gene probe generated by PCR. By comparison of the cDNA and the genomic DNA sequences, it was found that the complete nucleotide sequence encodes a putative polypeptide chain of 338 amino acids interrupted by 6 introns. The predicted amino acid sequence of this gene shows a high degree of sequence similarity to the GPD proteins from yeast and filamentous fungi. The promoter region contains a CT-rich stretch, two CAAT boxes, and a consensus TATA box. The possibility of using the gpd promoter in the construction of new transformation vectors is discussed.

Characterization of Osh3, an Oxysterol-binding Protein, in Filamentous Growth of Saccharomyces cerevisiae and Candida albicans: Hyang-sook Hur , Ji-Ho Ryu , Kwang-Hoon Kim , Jinmi Kim; J. Microbiol. 2006;44(5):523-529.; DOI: https://doi.org/2445 [pii]

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Abstract: OSH3 is one of the seven yeast homologues of the oxysterol binding proteins (OSBPs) which have the major binding affinity to the oxysterols and function as regulator of cholesterol biosynthesis in mammals. Mutational analysis of OSH3 showed that OSH3 plays a regulatory role in the yeast-to-hyphal transition through its oxysterol-binding domain in Saccharomyces cerevisiae. The OSH3 gene was also identified in the pathogenic yeast Candida albicans. Deletion of OSH3 caused a defect in the filamentous growth, which is the major cause of the C. albicans pathogencity. The filamentation defect of the mutation in the MAPK-associated transcription factor, namely cph1Δ was suppressed by overexpression of OSH3. These findings suggest the regulatory roles of OSH3 in the yeast filamentous growth and the functional conservations of OSH3 in S. cerevisiae and C. albicans.

Isolation and Characterization of the Smallest Bacteriophage P4 Derivatives Packaged into P4-Size Head in Bacteriophage P2-P4 System: Kyoung-Jin Kim , Jaeho Song; J. Microbiol. 2006;44(5):530-536.; DOI: https://doi.org/2444 [pii]

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Abstract: Bacteriophage P4, a satellite phage of coliphage P2, is a very useful experimental tool for the study of viral capsid assembly and cos-cleavage. For an in vitro cos-cleavage reaction study of the P2-P4 system, new shortened and selectable markers containing P4 derivative plasmids were designed as a substrate molecules. They were constructed by swapping the non-essential segment of P4 DNA for either the kanamycin resistance (kmr) gene or the ampicillin resistance (apr) gene. The size of the genomes of the resulting markers were 82% (P4 ash8 delRI:: kmr) and 79% (P4 ash8 delRI:: apr) of the wild type P4 genome. To determine the lower limit of genome size that could be packaged into the small P4-size head, these shortened P4 plasmids were converted to phage particles with infection of the helper phage P2. The conversion of plasmid P4 derivatives to bacteriophage particles was verified by the heat stability test and the burst size determination experiment. CsCl buoyant equilibrium density gradient experiments confirmed not only the genome size of the viable phage form of shortened P4 derivatives, but also their packaging into the small P4-size head. P4 ash8 delRI:: apr turned out to be the smallest P4 genome that can be packaged into P4-sized head.

Vibrio vulnificus Metalloprotease VvpE has no Direct Effect on Iron-uptake from Human Hemoglobin: Hui-Yu Sun , Song-Iy Han , Mi-Hwa Choi , Seong-Jung Kim , Choon-Mee Kim , Sung-Heui Shin; J. Microbiol. 2006;44(5):537-547.; DOI: https://doi.org/2443 [pii]

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Abstract: This study was designed to determine whether or not Vibrio vulnificus metalloprotease VvpE can promote iron uptake via the proteolytic cleavage of human hemoglobin. We found that V. vulnificus utilized hemoglobin as an iron source more efficiently via the vulnibactin-mediated iron-uptake system than via the HupA-mediated iron-uptake system and, of the proteases produced by V. vulnificus, VvpE was found to be the only protease capable of destroying hemoglobin. However, VvpE expression, on both the transcriptional and protein levels, was suppressed in iron-limited media. However, vvpE transcription, but not extracellular VvpE production, was reactivated by the addition of hemoglobin or inorganic iron into iron-limited media. Moreover, vvpE transcription began only in the late growth phase when V. vulnificus had already consumed most of the iron for growth. In addition, neither vvpE mutation nor in trans vvpE complementation affected the ability of V. vulnificus to acquire iron or to grow in iron-limited media or in cirrhotic ascites containing hemoglobin. Hemoglobin added into iron-limited media was not destroyed, but gradually formed an insoluble aggregate during culture; this aggregation of hemoglobin occurred regardless of vvpE mutation or complementation. These results indicate that VvpE is not required for efficient iron uptake from hemoglobin. On the contrary, hemoglobin or iron is required for efficient vvpE transcription. In addition, a discrepancy exists between vvpE transcription and extracellular VvpE production in iron-limited media containing inorganic iron or hemoglobin, which suggests that additional unknown posttranscriptional events may be involved in the extracellular production of VvpE.

Journal Article

Protective Immune Response of Bacterially-Derived Recombinant FaeG in Piglets: Huang Yahong , Wanqi Liang , Aihu Pan , Zhiai Zhou , Qiang Wang , Cheng Huang , Jianxiu Chen , Dabing Zhang; J. Microbiol. 2006;44(5):548-555.; DOI: https://doi.org/2442 [pii]

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Abstract: FaeG is the key factor in the infection process of K88ad enterotoxigenic Escherichia coli(ETEC) fimbrial adhesin. In an attempt to determine the possibility of expressing recombinant FaeG with immunogenicity for a new safe and high-production vaccine in E. coli, we constructed the recombinant strain, BL21 (DE3+K88), which harbors an expression vector with a DNA fragment of faeG, without a signal peptide. Results of 15% SDS-polyacrylamide slab gel analysis showed that FaeG can be stably over-expressed in BL21 (DE3+K88) as inclusion bodies without FaeE. Immunoglobulin G (IgG) and M (IgM) responses in pregnant pigs, with boost injections of the purified recombinant FaeG, were detected 4 weeks later in the sera and colostrum. An in vitro villius-adhesion assay verified that the elicited antibodies in the sera of vaccinated pigs were capable of preventing the adhesion of K88ad ETEC to porcine intestinal receptors. The protective effect on the mortality rates of suckling piglets born to vaccinated mothers was also observed one week after oral challenge with the virulent ETEC strain, C83907 (K88ad, CT+, ST+). The results of this study proved that the adhesin of proteinaceous bacterial fimbriae or pili could be overexpressed in engineered E. coli strains, with protective immune responses to the pathogen.

Research Support, Non-U.S. Gov'ts

Cloning and Characterization of a Thioredoxin Gene, CpTrx1, from the Chestnut Blight Fungus Cryphonectria parasitica: Ji-Hye Kim Dae-Hyuk Kim; J. Microbiol. 2006;44(5):556-561.; DOI: https://doi.org/2441 [pii]

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Abstract: A differential display for the expression profiles of wild-type Cryphonectria parasitica and its virally-infected isogenic hypovirulent strain revealed several transcripts of interest, which evidenced significant matches with fungal genes of known function. Among which, we have further analyzed an amplified PCR product with significant sequence similarity to the known fungal stress-responsive thioredoxin gene from Neurospora crassa. The product of the cloned thioredoxin gene, CpTrx1, consists of 117 amino acids, with a predicted molecular mass of 13.0 kDa and a pI of 5.4. Sequence comparisons demonstrated that the deduced protein sequence of the CpTrx1 gene evidenced a high degree of homology to all known thioredoxins, with the highest degree of homology with trx1, a thioredoxin gene from Saccharomyces cerevisiae, and evidenced a preservation of the conserved hall markresidues (Trp-Cys-Gly-Pro-Cys) at the active site of thioredoxin. The E. coli-generated CpTRX1 manifested thioredoxin activity, according to the insulin reduction assay, which indicates that the cloned gene does indeed encode for the C. parasitica thioredoxin.

Simple Method for a Cell Count of the Colonial Cyanobacterium, Microcystis sp.: Seung-Hyun Joung , Choong-Jae Kim , Chi-Yong Ahn , Kam-Yong Jang , Sung Min Boo , Hee-Mock Oh; J. Microbiol. 2006;44(5):562-565.; DOI: https://doi.org/2440 [pii]

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Abstract: The cell counting of colonial Microcystis spp. is a rather difficult and error-prone proposition, as this genus forms irregularly-shaped and irregularly-sized colonies, which are packed with cells. Thus, in order to facilitate a cell count, four methods of dividing the colonies into single cells were compared, including vortexing, sonication, TiO2 treatment, and boiling. As a result, the boiling method was determined to generate the greatest number of single cells from a colony, and all colonies were found to have divided completely after only 6 min of treatment. Furthermore, no significant cell destruction, which might alter the actual cell density, was detected in conjunction with the boiling method (P = 0.158). In order to compute the cell number more simply, the relationship between the colony size and the cell number was determined, via the boiling method. The colony volume, rather than the area or diameter was correlated more closely with the cell number (r2 = 0.727), thereby suggesting that the cell numbers of colonial Microcystis sp. can also be estimated effectively from their volumes.

Archaeal Communities in Mangrove Soil Characterized by 16S rRNA Gene Clones: Bing Yan , Kui Hong , Zi-Niu Yu; J. Microbiol. 2006;44(5):566-571.; DOI: https://doi.org/2439 [pii]

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Abstract: An archaeal 16S rRNA gene library was constructed from mangrove soil. Phylogenetic analysis revealed archaea in mangrove soil including the Crenarchaeota (80.4%) and Euryarchaeota (19.6%) phyla. The archaeal community in mangrove soil appears to be a mixture of organisms found in a variety of environments with the majority being of marine origin.

Bacterial Diversity in the Human Saliva from Different Ages: Jung-Gyu Kang , Seong Hwan Kim , Tae-Young Ahn; J. Microbiol. 2006;44(5):572-576.; DOI: https://doi.org/2438 [pii]

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Abstract: To obtain primary idea on oral bacterium species that are generally present in periodotally healthy Koreans, the oral bacterial flora in the saliva of four periodontally healthy Koreans at different ages (5, 32, 35, 65) was investigated in this study. For this investigation, 16SrRNA gene clone libraries were generated from the saliva of the four healthy Koreans, and 50 clones were randomly selected from each saliva clone library and sequenced. Totally, 37 different kinds of bacterial 16S rRNA gene sequences were identified based on sequence homology search through GenBank database. The 37 kinds of saliva clone sequences were classified to 14 genera and 2 uncultured and 1 unidentified bacteria. Among the 14 identified genera, Streptococcus, Prevotella, and Veillonella were common genera, and Streptococcus was dominant genus that accounted for 7 different species. Among the seven Streptococcus species, S. salivarius appeared as the most common species. More numbers of species belonging to the genera Streptococcus and Prevotella was present in saliva from ages 32 and 35. While saliva from ages 5 and 65 showed more numbers of species belonging to the genera Rothia, including potential pathogenic species. Overall, saliva of a young child and a senior showed higher bacterial diversity than that of young adults.

Journal Article

Nucleocapsid Amino Acids 211 to 254, in Particular, Tetrad Glutamines, are Essential for the Interaction Between the Nucleocapsid and Membrane Proteins of SARS-Associated Coronavirus: Xiaonan Fang , Lin-Bai Ye , Yijuan Zhang , Baozong Li , Shanshan Li , Lingbao Kong , Yuhua Wang , Hong Zheng , Wei Wang , Zhenghui Wu; J. Microbiol. 2006;44(5):577-580.; DOI: https://doi.org/2437 [pii]

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Abstract: GST pull-down assays were used to characterize the SARS-CoV membrane (M) and nucleocapsid (N) interaction, and it was found that the amino acids 211-254 of N protein were essential for this interaction. When tetrad glutamines (Q) were replaced with glutamic acids (E) at positions of 240-243 of the N protein, the interaction was disrupted.

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