Journal of Microbiology

Volume 43(2); April 2005

Review

Shigellosis: Swapan Kumar Niyogi; J. Microbiol. 2005;43(2):133-143.; DOI: https://doi.org/2172 [pii]

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Abstract: Shigellosis is a global human health problem. Four species of Shigella i.e. S. dysenteriae, S. flexneri, S. boydii and S. sonnei are able to cause the disease. These species are subdivided into serotypes on the basis of O-specific polysaccharide of the LPS. Shigella dysenteriae type 1 produces severe disease and may be associated with life-threatening complications. The symptoms of shigellosis include diarrhoea and/or dysentery with frequent mucoid bloody stools, abdominal cramps and tenesmus. Shigella spp. cause dysentery by invading the colonic mucosa. Shigella bacteria multiply within colonic epithelial cells, cause cell death and spread laterally to infect and kill adjacent epithelial cells, causing mucosal ulceration, inflammation and bleeding. Transmission usually occurs via contaminated food and water or through person-to-person contact. Laboratory diagnosis is made by culturing the stool samples using selective/differential agar media. Shigella spp. are highly fragile organism and considerable care must be exercised in collecting faecal specimens, transporting them to the laboratories and in using appropriate media for isolation. Antimicrobial agents are the mainstay of therapy of all cases of shigellosis. Due to the global emergence of drug resistance, the choice of antimicrobial agents for treating shigellosis is limited. Although single dose of norfloxacin and ciprofloxacin has been shown to be effective, they are currently less effective against S. dysenteriae type 1 infection. Newer quinolones, cephalosporin derivatives, and azithromycin are the drug of choice. However, fluoroquinolone-resistant S. dysenteriae type 1 infection have been reported. Currently, no vaccines against Shigella infection exist. Both live and subunit parenteral vaccine candidates are under development. Because immunity to Shigella is serotype-specific, the priority is to develop vaccine against S. dysenteriae type 1 and S. flexneri type 2a. Shigella species are important pathogens responsible for diarrhoeal diseases and dysentery occurring all over the world. The morbidity and mortality due to shigellosis are especially high among children in developing countries. A recent review of literature (Kotloff et al.,1999) concluded that, of the estimated 165 million cases of Shigella diarrhoea that occur annually, 99% occur in developing countries, and in developing countries 69% of episodes occur in children under five years of age. Moreover, of the ca.1.1 million deaths attributed to Shigella infections in developing countries, 60% of deaths occur in the under-five age group. Travellers from developed to developing regions and soldiers serving under field conditions are also at an increased risk to develop shigellosis.

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

Archaeal Diversity in Tidal Flat Sediment as Revealed by 16S rDNA Analysis: Bong-Soo Kim , Huyn-Myung Oh , Hojeong Kang , Jongsik Chun; J. Microbiol. 2005;43(2):144-151.; DOI: https://doi.org/2170 [pii]

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Abstract: During the past ten years, Archaea have been recognized as a widespread and significant component of marine picoplankton assemblages. More recently, the presence of novel archaeal phylogenetic lineages has been discovered in coastal marine environments, freshwater lakes, polar seas, and deep-sea hydrothermal vents. Therefore, we conducted an investigation into the archaeal community existing in tidal flat sediment collected from Ganghwa Island, Korea. Phylogenetic analysis of archaeal 16S rDNA amplified directly from tidal flat sediment DNA revealed the presence of two major lineages, belonging to the Crenarchaeota (53.9%) and Euryarchaeota (46.1%) phyla. A total of 102 clones were then sequenced and analyzed by comprehensive phylogenetic analysis. The sequences determined in our samples were found to be closely related to the sequences of clones which had been previously obtained from a variety of marine environments. Archaeal clones exhibited higher similarities (83.25 - 100%) to sequences from other environments in the public database than did those (75.22 - 98.46%) of previously reported bacterial clones obtained from tidal flat sediment. The results of our study suggest that the archaeal community in tidal flat sediment is remarkably diverse.

Sphingopyxis granuli sp. nov., a [beta]-Glucosidase-Producing Bacterium in the Family Sphingomonadaceae in [alpha]-4 Subclass of the Proteobacteria: Myung Kyum Kim , Wan-Taek Im , Hiroyuki Ohta , Myungjin Lee , Sung-Taik Lee; J. Microbiol. 2005;43(2):152-157.; DOI: https://doi.org/2169 [pii]

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Abstract: Strain Kw07^T, a Gram-negative, non-spore-forming, rod-shaped bacterium, was isolated from granules in an Up-flow Anaerobic Sludge Blanket (UASB) bioreactor used in the treatment of brewery wastewater. 16S rRNA gene sequence analysis revealed that strain Kw07^T belongs to the [alpha]-4 subclass of the Proteobacteria, and the highest degree of sequence similarity was determined to be to Sphingopyxis macrogoltabida IFO 15033^T (97.8%). Chemotaxonomic data revealed that strain Kw07^T possesses a quinone system with the predominant compound Q-10, the predominant fatty acid C_18:1 w7c, and sphingolipids, all of which corroborated our assignment of the strain to the Sphingopyxis genus. The results of DNA-DNA hybridization and physiological and biochemical tests clearly demonstrated that strain Kw07^T represents a distinct species. Based on these data, Kw07^T (= KCTC 12209^T = NBRC 100800^T) should be classified as the type strain for a novel Sphingopyxis species, for which the name Sphingopyxis granuli sp. nov. has been proposed.

The Taxonomy of Psilocybe fagicola-complex: Gaston Guzman , James Q. Jacobs , Florencia Ramiez-Guillen , Dulce Murrieta , Etelvina Gandara; J. Microbiol. 2005;43(2):158-165.; DOI: https://doi.org/2168 [pii]

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Abstract: Psilocybe fagicola comprises a complex of more than eight species, six of them in Mexico, and all of them possessing a long pseudorhiza, a characteristic not listed by Heim and Cailleux in 1959 in the original description of the type species, but described by Guzman in 1978 and 1983. The description of Psilocybe fagicola s.s. is here emended to include the length of the cheilocystidia of (6-) 12-20 (-30) um, as well as the absence or scarcity of pleurocystidia. Psilocybe xalapensis and P. wassoniorum are considered to be synonymous with P. fagicola s.s. However, Psilocybe banderillensis and P. herrerae from Mexico, P. columbiana from Colombia, and P. keralensis from India are considered to be valid species within this complex. Moreover, P. novoxalapensis and P. teofilae, both from Mexico, are described as new species. Length of spores, presence or absence of pleurocystidia and their variations, and type of cheilocystidia constitute the principal defining characteristics of the species. Setaceous hyphae at the base of the stipe, as well as caulocystidia, lack taxonomic value, as do other morphological characteristics, including pileipellis and subpileipellis. A key to the eight considered species is also presented within the paper.

Effects of Sulfate Concentration on the Anaerobic Dechlorination of Polychlorinated Biphenyls in Estuarine Sediments: Young-Cheol Cho , Kyoung-Hee Oh; J. Microbiol. 2005;43(2):166-171.; DOI: https://doi.org/2167 [pii]

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Abstract: In order to determine the effects of sulfate concentration on the anaerobic dechlorination of polychlorinated biphenyls, sediments spiked with Aroclor 1242 were made into slurries using media which had various sulfate concentrations ranging from 3 to 23 mM. The time course of dechlorination clearly demonstrated that dechlorination was inhibited at high concentration of sulfate due to less dechlorination of meta-substituted congeners. When the dechlorination patterns were analyzed by the calculation of Euclidean distance, the dechlorination pathway in the 3 mM sulfate samples was found to be different from that observed in the 13 mM samples, although the extent of dechlorination in these two samples was similar. It is possible that the dechlorination in the high sulfate concentration samples is inhibited by the suppression of growth of methanogen, which have been shown to be meta-dechlorinating microorganisms.

Molecular Characterization of TEM-type [beta]-Lactamases Identified in Cold-Seep Sediments of Edison Seamount (South of Lihir Island, Papua New Guinea): Jae Seok Song , Jeong Ho Jeon , Jung Hun Lee , Seok Hoon Jeong , Byeong Chul Jeong , Sang-Jin Kim , Jung-Hyun Lee , Sang Hee Lee; J. Microbiol. 2005;43(2):172-178.; DOI: https://doi.org/2165 [pii]

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Abstract: To determine the prevalence and genotypes of [beta]-lactamases among clones of a metagenomic library from the cold-seep sediments of Edison seamount (10,000 years old), we performed pulse-field gel electrophoresis, antibiotic susceptibility testing, pI determination, and DNA sequencing analysis. Among the 8,823 clones of the library, thirty clones produced [beta]-lactamases and had high levels of genetic diversity. Consistent with minimum inhibitory concentration patterns, we found that five (16.7%) of thirty clones produced an extended-spectrum [beta]-lactamase. 837- and 259-bp fragments specific to bla_TEM genes were amplified, as determined by banding patterns of PCR amplification with designed primers. TEM-1 was the most prevalent [beta]-lactamase and conferred resistance to ampicillin, piperacillin, and cephalothin. TEM-116 had a spectrum that was extended to ceftazidime, cefotaxime, and aztreonam. The resistance levels conferred by the pre-antibiotic era alleles of TEM-type [beta]-lactamases were essentially the same as the resistance levels conferred by the TEM-type alleles which had been isolated from clinically resistant strains of bacteria of the antibiotic era. Our first report on TEM-type [beta]-lactamases of the pre-antibiotic era indicates that TEM-type [beta]-lactamases paint a picture in which most of the diversity of the enzymes may not be the result of recent evolution, but that of ancient evolution.

Enhancement of Gene Delivery to Cancer Cells by a Retargeted Adenovirus: Kwang Seok Oh , Jeffrey A. Engler , Insil Joung; J. Microbiol. 2005;43(2):179-182.; DOI: https://doi.org/2164 [pii]

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Abstract: The inefficiency of in vivo gene transfer using currently available vectors reflects a major hurdle in cancer gene therapy. Both viral and non-viral approaches that improve gene transfer efficiency have been described, but suffer from a number of limitations. Herein, a fiber-modified adenovirus, carrying the small peptide ligand on the capsid, was tested for the delivery of a transgene to cancer cells. The fiber-modified adenovirus was able to mediate the entry and expression of a [beta]-galactosidase into cancer cells with increased efficiency compared to the unmodified adenovirus. Particularly, the gene transfer efficiency was improved up to 5 times in OVCAR3 cells, an ovarian cancer cell line. Such transduction systems hold promise for delivering genes to transferrin receptor overexpressing cancer cells, and could be used for future cancer gene therapy.

Staphylococcus aureus Siderophore-Mediated Iron-Acquisition System Plays a Dominant and Essential Role in the Utilization of Transferrin-Bound Iron: Ra-Young Park , Hui-Yu Sun , Mi-Hwa Choi , Young-Hoon Bai , Sung-Heui Shin; J. Microbiol. 2005;43(2):183-190.; DOI: https://doi.org/2163 [pii]

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Abstract: Staphylococcus aureus is known to be capable of utilizing transferrin-bound iron, via both siderophore- and transferrin-binding protein (named IsdA)-mediated iron-acquisition systems. This study was designed in order to determine which iron-acquisition system plays the essential or dominant role with respect to the acquisition of iron from human transferrin, in the growth of S. aureus. Holotransferrin (HT) and partially iron-saturated transferrin (PT), but not apotransferrin (AT), were found to stimulate the growth of S. aureus. S. aureus consumed most of the transferrin-bound iron during the exponential growth phase. Extracellular proteases were not, however, involved in the liberation of iron from transferrin. Transferrin-binding to the washed whole cells via IsdA was not observed during the culture. The expression of IsdA was observed only in the deferrated media with AT, but not in the media supplemented with PT or HT. In contrast, siderophores were definitely produced in the deferrated media with PT and HT, as well as in the media supplemented with AT. The siderophores proved to have the ability to remove iron directly from transferrin, but the washed whole cells expressing IsdA did not. In the bioassay, the growth of S. aureus on transferrin-bound iron was stimulated by the siderophores alone. These results demonstrate that the siderophore-mediated iron-acquisition system plays a dominant and essential role in the uptake of iron from transferrin, whereas the IsdA-mediated iron-acquisition system may play only an ancillary role in the uptake of iron from transferrin.

Functional Characterization of the Gene Encoding UDP-glucose: Tetrahydrobiopterin [alpha]-Glucosyltransferase in Synechococcus sp. PCC 7942: En-Young Cha , Jeong Soon Park , Sireong Jeon , Jin Seon Kong , Yong Kee Choi , Jee-Youn Ryu , Youn-Il Park , Young Shik Park; J. Microbiol. 2005;43(2):191-195.; DOI: https://doi.org/2162 [pii]

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Abstract: In this study, we attempted to characterize the Synechococcus sp. PCC 7942 mutant resultant from a disruption in the gene encoding UDP-glucose: tetrahydrobiopterin [alpha]-glucosyltransferase (BGluT). 2D-PAGE followed by MALDI-TOF mass spectrometry revealed that phycocyanin rod linker protein 33K was one of the proteins expressed at lower level in the BGluT mutant. BGluT mutant cells were also determined to be more sensitive to high light stress. This is because photosynthetic O_2 exchange rates were significantly decreased, due to the reduced number of functional PSIs relative to the wild type cells. These results suggested that, in Synechococcus sp. PCC 7942, BH4-glucoside might be involved in photosynthetic photoprotection.

Journal Articles

Stabilities of Artificially Transconjugated Plasmids for the Bioremediation of Cocontaminated Sites: Kyung Pyo Yoon; J. Microbiol. 2005;43(2):196-203.; DOI: https://doi.org/2161 [pii]

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Abstract: Here, we attempted to evaluate the activity of artificially transconjugated multiple plasmids in “designer biocatalysts” for the bioremediation of cocontaminated sites under nonselective conditions. We observed profound losses in the percent survivals of artificially transconjugated plasmid activity (66 - 78% loss immediately after freeze-drying, 99.45 - 99.88% loss by the end of 6 months storage) in reconstituted Pseudomonas sp. KM12TC. Such unpredictable high losses of this particular plasmid appeared to clearly be a deleterious effect. However, even after 6 months of storage, the cells remained able to degrade 95% of phenol within 9 days, and the full efflux of ^73As, as compared to that of the non-freeze-dried cells, was successfully achieved 4 to 9 days later. These results indicate that “stable designer biocatalysts” can remain viable, even after freeze-drying and 6 months of storage.

Identification of Non-mutans Streptococci Organisms in Dental Plaques Recovering on Mitis-Salivarius Bacitracin Agar Medium: So Young Yoo , Pyung Sik Kim , Ho-Keel Hwang , Seong-Hoon Lim , Kwang-Won Kim , Son-Jin Choe , Byung-Moo Min , Joong-Ki Kook; J. Microbiol. 2005;43(2):204-208.; DOI: https://doi.org/2160 [pii]

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Abstract: The objective of this study was to both isolate and identify non-mutans streptococci organisms (non-MSO) from dental plaques recovered on mitis-salivarius sucrose bacitracin agar (MSB) plates. The dental plaque samples, which had been collected from 63 human subjects, were diluted and plated on MSB. The bacteria growing on the MSB plates were then identified with biochemical tests, as well as with 16S rDNA cloning and sequencing techniques. Our data indicated that bacteria from 30 subjects had been recovered on the MSB plates. Among the 21 typical colonies selected from the 30 subjects, 12 colonies, derived from 10 subjects, were identified as non-MSO. These 12 colonies were determined to be Streptococcus anginosus (8 colonies), S. sanguinis (1 colony), and Pantoea agglomerans (3 colonies). These results strongly suggest that a new selective medium will be required for the reliable isolation of mutans streptococci.

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

Identification of Actinobacillus actinomycetemcomitans Using Species-Specific 16S rDNA Primers: Su-Gwan Kim , Soo-Heung Kim , Mi-Kwang Kim , Hwa-Sook Kim , Joong-Ki Kook; J. Microbiol. 2005;43(2):209-212.; DOI: https://doi.org/2159 [pii]

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Abstract: The purpose of this study was to develop species-specific PCR primers for use in the identification and detection of Actinobacillus actinomycetemcomitans. These primers target variable regions of the 16S ribosomal RNA coding gene (rDNA). We assessed the specificity of the primers against 9 A. actinomycetemcomitans strains and 11 strains (3 species) of the Haemophilus genus. Primer sensitivity was determined by testing serial dilutions of the purified genomic DNAs of A. actinomycetemcomitans ATCC 33384^T. Our obtained data revealed that we had obtained species-specific amplicons for all of the tested A. actinomycetemcomitans strains, and that none of these amplicons occurred in any of the other species. Our PCR protocol proved able to detect as little as 4 fg of A. actinomycetemcomitans chromosomal DNA. Our findings suggest that these PCR primers are incredibly sensitive, and should prove suitable for application in epidemiological studies, as well as the diagnosis and monitoring of periodontal pathogens after treatment for periodontitis.

Molecular Taxonomy of a Soil Actinomycete Isolate, KCCM10454 Showing Neuroprotective Activity by 16S rRNA and rpoB Gene Analysis: Bong-Hee Lee , Hong Kim , Hyun-Ju Kim , Yoon-Kyu Lim , Kyung-Hee Byun , Brian Hutchinson , Chang-Jin Kim , Young-Hwan Ko , Keun-Hwa Lee , Chang-Yong Cha , Yoon-Hoh Kook , Bum-Joon Kim; J. Microbiol. 2005;43(2):213-218.; DOI: https://doi.org/2158 [pii]

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Abstract: Epilepsy constitutes a significant public health problem, and even the newest drugs and neurosurgical techniques have proven unable to cure the disease. In order to select a group of isolates which could generate an active compound with neuroprotective or antiepileptic properties, we isolated 517 actinomycete strains from soil samples taken from Jeju Island, in South Korea. We then screened these strains for possible anti-apoptotic effects against serum deprivation-induced hippocampal cell death, using the 3-(4, 5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) assay as an in vitro test. The excitotoxic glutamate analog, kainic acid (KA), was used to induce seizures in experimental mice in our in vivo tests. As a result of this testing, we located one strain which exhibited profound neuroprotective activity. This strain was identified as a Streptomyces species, and exhibited the rifampin-resistant genotype, Asn(AAC)^442, according to the results of 16S rRNA and rpoB gene analyses

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