Journal of Microbiology

Volume 46(3); June 2008

Review

REVIEW] Dinoflagellates, Diatoms, and Their Viruses: Keizo Nagasaki; J. Microbiol. 2008;46(3):235-243. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0098-y

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107 Citations

Abstract: Since the first discovery of the very high virus abundance in marine environments, a number of researchers were fascinated with the world of “marine viruses”, which had previously been mostly overlooked in studies on marine ecosystems. In the present paper, the possible role of viruses infecting marine eukaryotic microalgae is enlightened, especially summarizing the most up-to-the-minute information of marine viruses infecting bloom-forming dinoflagellates and diatoms. To author’s knowledge, ~40 viruses infecting marine eukaryotic algae have been isolated and characterized to different extents. Among them, a double-stranded DNA (dsDNA) virus “HcV” and a single-stranded RNA (ssRNA) virus “HcRNAV” are the only dinoflagellate-infecting (lytic) viruses that were made into culture; their hosts are a bivalve-killing dinoflagellate Heterocapsa circularisquama. In this article, ecological relationship between H. circularisquama and its viruses is focused. On the other hand, several diatom-infecting viruses were recently isolated and partially characterized; among them, one is infectious to a pen-shaped bloom-forming diatom species Rhizosolenia setigera; some viruses are infectious to genus Chaetoceros which is one of the most abundant and diverse diatom group. Although the ecological relationships between diatoms and their viruses have not been sufficiently elucidated, viral infection is considered to be one of the significant factors affecting dynamics of diatoms in nature. Besides, both the dinoflagellate-infecting viruses and diatom-infecting viruses are so unique from the viewpoint of virus taxonomy; they are remarkably different from any other viruses ever reported. Studies on these viruses lead to an idea that ocean may be a treasury of novel viruses equipped with fascinating functions and ecological roles.

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

Microeukaryotic Diversity in Marine Environments, an Analysis of Surface Layer Sediments from the East Sea: Soo-Je Park , Byoung-Joon Park , Vinh Hoa Pham , Dae-No Yoon , Si-Kwan Kim , Sung-Keun Rhee; J. Microbiol. 2008;46(3):244-249. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0237-x

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21 Citations

Abstract: Molecular techniques, based on clone library of 18S rRNA gene, were employed to ascertain the diversity of microeukaryotic organisms in sediments from the East Sea. A total of 261 clones were recovered from surface sediments. Most of the clone sequences (90%) were affiliated with protists, dominated by Ciliates (18%) and Dinoflagellates (19%) of Alveolates, phototrophic Stramenopiles (11%), and Cercozoa (20%). Many of the clones were related to uncultivated eukaryotes clones retrieved from anoxic environments with several highly divergent 18S rRNA gene sequences. However, no clones were related to cultivated obligate anaerobic protists. Protistan communities between subsurface layers of 1 and 9 cm shared 23% of total phylotypes which comprised 64% of total clones retrieved. Analysis of diversity indices and rarefaction curve showed that the protistan community within the 1 cm layer exhibited higher diversity than the 9 cm layer. Our results imply that diverse protists remain to be uncovered within marine benthic environments.

Phylogenetic Analysis on the Bacteria Producing Non-Volatile Fungistatic Substances: ZhiFang Li , ChangSong Zou , YueQiu He , MingHe Mo , KeQin Zhang; J. Microbiol. 2008;46(3):250-256. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0003-8

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5 Citations

Abstract: This study characterized the soil bacteria producing non-volatile fungistatic substances. Among the 2,100 colonies of soil bacteria randomly isolated from seven agricultural soil samples, 518 isolates (24.67% of total) showed fungistatic activity toward nematophagous fungi Paecilomyces lilacinus and Trichoderma viride by producing non-volatile substances. A phylogenetic analysis based on amplified ribosomal DNA restriction analysis (ARDRA) and 16S rDNA sequence placed the 518 bacteria in three groups of the domain Bacteria: Actinomycetales, Bacillales, and Gammaproteobacteria. Three genera, Arthrobacter, Bacillus, and Pseudomonas, were the most frequently encountered groups.

Auxin Production and Detection of the Gene Coding for the Auxin Efflux Carrier (AEC) Protein in Paenibacillus polymyxa: Fabio Faria Da Mota , Eliane Aparecida Gomes , Lucy Seldin; J. Microbiol. 2008;46(3):257-264. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0245-x

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30 Citations

Abstract: Different species of Paenibacillus are considered to be plant growth-promoting rhizobacteria (PGPR) due to their ability to repress soil borne pathogens, fix atmospheric nitrogen, induce plant resistance to diseases and/or produce plant growth-regulating substances such as auxins. Although it is known that indole-3-acetic acid (IAA) is the primary naturally occurring auxin excreted by Paenibacillus species, its transport mechanisms (auxin efflux carriers) have not yet been characterized. In this study, the auxin production of P. polymyxa and P. graminis, which are prevalent in the rhizospheres of maize and sorghum sown in Brazil, was evaluated. In addition, the gene encoding the Auxin Efflux Carrier (AEC) protein from P. polymyxa DSM36T was sequenced and used to determine if various strains of P. polymyxa and P. graminis possessed this gene. Each of the 68 P. polymyxa strains evaluated in this study was able to produce IAA, which was produced at concentrations varying from 1 to 17 μg/ml. However, auxin production was not detected in any of the 13 P. graminis strains tested in this study. Different primers were designed for the PCR amplification of the gene coding for the AEC in P. polymyxa, and the predicted protein of 319 aa was homologous to AEC from Bacillus amyloliquefaciens, B. licheniformis, and B. subtilis. However, no product was observed when these primers were used to amplify the genomic DNA of seven strains of P. graminis, which suggests that this gene is not present in this species. Moreover, none of the P. graminis genomes tested were homologous to the gene coding for AEC, whereas all of the P. polymyxa genomes evaluated were. This is the first study to demonstrate that the AEC protein is present in P. polymyxa genome.

Distribution of Marine Birnavirus in Cultured Olive Flounder Paralichthys olivaceus in Korea: Sung-Ju Jung , Seok-Ryel Kim , Il-Yong Joung , Shin-Ichi Kitamura , Hee-Taek Ceong , Myung-Joo Oh; J. Microbiol. 2008;46(3):265-273. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0004-7

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23 Citations

Abstract: Surveys of marine birnavirus (MABV) were undertaken in cultured olive flounder Paralichthys olivaceus from the south and west coastal areas and Jeju in Korea during the period January 1999 to April 2007. MABV was detected in all seasons from the fry, juveniles and adult fish from the areas examined. Evident cytopathic effects of the virus including rounding and cell lysis were observed in chinook salmon embryo (CHSE-214) and rainbow trout gonad (RTG-2) cells, but not in fathead minnow (FHM) and epithelial papilloma of carp (EPC) cells. Nucleotide sequences of the VP2/NS junction region of the Korean isolates showed 97.8%~100% similarity, and they belonged to the same genogroup. Cross neutralization tests with serotype-specific rabbit antisera against MABV strains exhibited a close antigenic relationships between strains, and were distinct from infectious pancreatic necrosis virus (IPNV) strains. Coinfection of MABV with bacteria (Streptococcus iniae, Vibrio spp.) and viruses (nervous necrosis virus, lymphocystis disease virus, viral hemorrhagic septicemia virus) was observed.

Journal Article

Monitoring of Algicidal Bacterium, Alteromonas sp. Strain A14 in its Application to Natural Cochlodinium polykrikoides Blooming Seawater Using Fluorescence In Situ Hybridization: Bo-Kyung Lee , Toshiya Katano , Shin-Ichi Kitamura , Myung-Joo Oh , Myung-Soo Han; J. Microbiol. 2008;46(3):274-282. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0238-9

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33 Citations

Abstract: The red tide of dinoflagellate, Cochlodinium polykrikoides has frequently occurred in coastal waters, causing severe damage to fisheries. In the present study, the algicidal bacterium Alteromonas sp. A14 isolated from the southern coast of Korea was applied to a red tide of C. polykrikoides in a laboratory experiment. In the experiment, the abundance of the strain A14 was monitored using fluorescence in situ hybridization. Inoculation of the A14 at a final cell density of 9.0×105 cells/ml caused a significant decrease in C. polykrikoides abundance from 1,830 to 700 cells/ml during 2 days, while abundances of harmless diatoms rapidly increased from 3 days. Abundances of both A14 and other bacteria increased to 1 day. After 1 day, with flagellate abundance increased, bacterial abundance decreased. Finally, algicidal bacterial abundance decreased to 3.5×104 cells/ml. In the biological control of harmful algal blooms, in addition to decrease in target algal abundance and not occurrence of other harmful blooms, decrease in abundance of utilized organism is also important. This study emphasizes the importance of monitoring the inoculated bacterium when applying bacterium to natural seawater.

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

Synergistic Effects of the Combination of Galangin with Gentamicin against Methicillin-Resistant Staphylococcus aureus: Young-Seob Lee , Ok-Hwa Kang , Jang-Gi Choi , You-Chang Oh , Hee-Sung Chae , Jong Hak Kim , Hyun Park , Dong Hwan Sohn , Zheng-Tao Wang , Dong-Yeul Kwon; J. Microbiol. 2008;46(3):283-288. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0012-7

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66 Citations

Abstract: The antimicrobial killing activity toward methicillin-resistant Staphylococcus aureus (MRSA) has been a serious emerging global issue. New effective antimicrobials and/or new approaches to settle this issue are urgently needed. The oriental herb, Alpinia officinarum, has been used in Korea for several hundreds of years to treat various infectious diseases. As it is well known, one of the active constituents of Alpinia officinarum is galangin. Against the 17 strains, the minimum inhibitory concentrations (MICs) of galangin (GAL) were in the range of 62.5~125 μg/ml, and the MICs of gentamicin (GEN) ranged from 1.9 μg/ml to 2,000 μg/ml. The fractional inhibitory concentrations (FICs) of GAL, in combination with GEN, against 3 test strains were 0.4, 3.9, and 250 μg/ml, and were all 15.62 μg/ml in GEN. The FIC index showed marked synergism in the value range of 0.19 to 0.25. By determining time-kill curves, also confirmed the low synergism of the GAL and GEN combination against 4 h, 8 h, 12 h, and 24 h cultured MRSA. The time-kill study results indicated a low synergistic effect against 3 test strains. Thus, the mixture of GAL and GEN could lead to the development of new combination antibiotics against MRSA infection.

Inactivation of Barotolerant Strains of Listeria monocytogenes and Escherichia coli O157:H7 by Ultra High Pressure and tert-Butylhydroquinone Combination: Yoon-Kyung Chung , Ahmed E. Yousef; J. Microbiol. 2008;46(3):289-294. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0090-6

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8 Citations

Abstract: Antimicrobial efficacy of ultra-high-pressure (UHP) can be enhanced by application of additional hurdles. The objective of this study was to systematically assess the enhancement in pressure lethality by TBHQ treatment, against barotolerant strains of Escherichia coli O157:H7 and Listeria monocytogenes. Two L. monocytogenes Scott A and the barotolerant OSY-328 strain, and two E. coli O157:H7 strains, EDL-933 and its barotolerant mutant, OSY-ASM, were tested. Cell suspensions containing TBHQ (50 ppm, dissolved in dimethyl sulfoxide) were pressurized at 200 to 500 MPa (23±2°C) for 1 min, plated on tryptose agar and enumerated the survivors. The TBHQ-UHP combination resulted in synergistic inactivation of both pathogens, with different degrees of lethality among strains. The pressure lethality threshold, for the combination treatment, was lower for E. coli O157:H7 (≥ 200 MPa) than for L. monocytogenes (> 300 MPa). E. coli O157:H7 strains were extremely sensitive to the TBHQ-UHP treatment, compared to Listeria strains. Interestingly, a control treatment involving DMSO-UHP combination consistently resulted in higher inactivation than that achieved by UHP alone, against all strains tested. However, sensitization of the pathogens to UHP by the additives (TBHQ in DMSO) was prominently greater for UHP than DMSO. Differences in sensitivities to the treatment between these two pathogens may be attributed to discrepancies in cellular structure or physiological functions.

Description of Streptomyces neopeptinius sp. nov., an Actinobacterium with Broad Spectrum Antifungal Activities: Ji Hye Han , In Cheon Hwang , Sung Heun Cho , Cheol Jang , Nam Gyu Kim , Seung Hun Yu , Yong Man Yu , Seung Bum Kim; J. Microbiol. 2008;46(3):295-299. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0011-8

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6 Citations

Abstract: A streptomycete strain producing broad-spectrum antifungal substances was taxonomically characterized. The strain, designated KNF 2047T (= SH-09T= KCTC 10586BPT), was found to form extensively branching aerial and substrate mycelia, and produce spiny-ornamented spores with loose spiral chains. The whole cell hydrolyzates contained major amount of LL-diaminopimelic acid. The major fatty acids of the phospholipids were saturated and branched fatty acids containing 14~17 carbons, and the major isoprenoid quinones were hexa- and octa-hydrogenated menaquinones with 9 isoprene units. The phylogenetic analysis using the 16S rRNA gene indicated that the strain belongs to the genus Streptomyces but forms an independent phyletic line. These results clearly demonstrate that strain KNF2047T forms a new center of taxonomic variation within Streptomyces, for which the name Streptomyces neopeptinius sp. nov. is proposed.

Cyanobacterial Hybrid Kinase Sll0043 Regulates Phototaxis by Suppressing Pilin and Twitching Motility Protein: Bong-Jeong Shin , Jeehyun Oh , Sungsoo Kang , Young-Ho Chung , Young Mok Park , Young Hwan Kim , Seungil Kim , Jong Bhak , Jong-Soon Choi; J. Microbiol. 2008;46(3):300-308. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0212-6

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8 Citations

Abstract: The unicellular cyanobacterium Synechocystis sp. PCC 6803 glides toward a light source through the interplay of positive phototaxis genes and proteins. In genetic analysis, the complete disruption of the hybrid sensory kinase sll0043 produced negative phototaxis. Furthermore, Sll0043 was found to be a hub protein by in silico prediction of protein-protein interaction, in which Sll0043 was predominantly linked to seven two-component proteins with high confidence. To understand the regulation and networking of positive phototaxis proteins, the proteomic profile of the sll0043 mutant was compared to that of wild-type. In the sll0043 mutant, 18 spots corresponding to 15 unique proteins were altered by 1.3 to 59 fold; the spots were identified by 2-DE/MALDI-MS analysis. Down-regulated proteins in the sll0043 null-mutant included chaperonins, superoxide dismutase, and phycocyanin β-subunit. In contrast, nine proteins involved in photosynthesis, translation, regulatory function, and other functions were up-regulated. In particular, a twitching motility protein (PilT1) was induced over 2-fold in sll0043 mutant. Moreover, semiquantitative and quantitative RT-PCR analysis revealed that pilin (pilA1), pili motor (pilT1), and pili switch gene (pilT2) were significantly increased in sll0043 mutant. These results suggest that the hybrid kinase Sll0043 regulates positive phototaxis by suppressing the expression of pili biosynthesis and regulatory genes and through the interplay with positive phototaxis/motility two-component proteins.

Cloning and Characterization of the Gene Cluster for Biosynthesis of Ectoine from Nesterenkonia halobia DSM 20541: Bo Zhang , Xin Bao , Lei Wang , Su Sheng Yang; J. Microbiol. 2008;46(3):309-318. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0001-x

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Abstract: The ectABC genes encoding the biosynthesis of ectoine were identified from Nesterenkonia halobia DSM 20541. The intergenic regions of the ectABC genes from N. halobia DSM 20541 were more loosely spaced than those that had been reported before. The amino acid sequence deduced from ectABC of the strain was highly homologous to the EctABC of Brevibacterium linens BL2 (EctA 50%, EctB 70%, and EctC 68% identities). The osmoprotection of ectABC was studied in the Escherichia coli KNabc and E. coli XL1-Blue. The results revealed that ectABC could shorten the lag phase and enhance the final OD600 of E. coli XL1-Blue in MM63 medium containing 0.68 M NaCl, and could initiate KNabc growth in 0.2 M NaCl. Ectoine was proven to be accumulated in E. coli KNabc/pGEM-Nect using HPLC-UV, and validated by LC-MSD-Trap-VL.

Molecular Detection and Characterization of Human Enteroviruses in Korean Surface Water: Gyucheol Lee , Chanhee Lee; J. Microbiol. 2008;46(3):319-324. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0232-2

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8 Citations

Abstract: In this study, the genetic epidemiology of enteroviruses (EVs) in Korean surface water was evaluated by conducting phylogenetic analyses of the nucleotide sequences of the 5’ non-coding region (5’ NCR), which was determined by RT-PCR analysis of total culturable virus assay-positive samples. The results showed that the nucleotide sequences of the EVs could be classified into 4 genetic clusters, and that the predominant presence of Korea EVs were very similar to echoviruses type 30. Interestingly, two nucleotide sequences were very similar to those of coxsackievirus type B1 isolated from aseptic meningitis patients in Seoul, Korea, implying the possibility of a common source for the viruses circulated in water systems and humans. In addition, 3 nucleotide sequences clustered strongly with the nucleotide sequences from China or Japan, and one fell into the same cluster as echovirus type 11 from Taiwan, which suggests that EVs in Asia may have evolved in a region-specific manner. Taken together, the results of this study revealed that EVs from Korea surface waters could be genetically classified as coxsackieviruses or echoviruses, and that they evolved in Asia in a region-specific manner.

Enteric Bacteria Isolated from Acute Diarrheal Patients in the Republic of Korea between the Year 2004 and 2006: Seung-Hak Cho , Hyun-Ho Shin , Yeon-Hwa Choi , Mi-Sun Park , Bok-Kwon Lee; J. Microbiol. 2008;46(3):325-330. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0015-4

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41 Citations

Abstract: In an epidemiological survey of human enterobacterial infections in the Republic of Korea during three years from 2004 to 2006, we isolated 1,784 (6.2%, isolation rate of enteropathogens from stool samples) in 2004, 2,547 (9.5%) in 2005 and 3,506 bacteria (12.3%) from people who visited clinics. Among the isolated bacteria, pathogenic Escherichia coli, especially, EAEC was the most frequently identified pathogen in both urban and rural regions followed by Staphylococcus aureus, Salmonella species, Bacillus cereus, Vibrio parahaemolyticus, Campylobacter jejuni, Clostridium perfringens, and Shigella species. Distinct seasonality was found in V. parahaemolyticus species, while this pathogen showed no age-specific patterns. However, other bacteria, i.e., pathogenic E. coli, S. aureus, Salmonella spp., and B. cereus showed similar seasonality throughout the year, showing a slight increase in the infection rate during the summer months and high prevalence among children under 10 years of age and elder-age people. The antibiotic susceptibility patterns of pathogenic E. coli, Salmonella spp., and S. aureus showed high resistance to penicillins. However, both pathogenic E. coli and Salmonella spp. were susceptible to several cephems, imipenem, and amikacin. Moreover, S. aureus strains resistant to vancomycin were not found. In conclusion, these surveillances can play an important role for the control and prevention to the diseases originated by enteritis bacteria.

The Changes of Proteomes Components of Helicobacter pylori in Response to Acid Stress without Urea: Chunhong Shao , Qunye Zhang , Wei Tang , Wei Qu , Yabin Zhou , Yundong Sun , Han Yu , Jihui Jia; J. Microbiol. 2008;46(3):331-337. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0062-x

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15 Citations

Abstract: Acid stress is the most obvious challenge Helicobacter pylori encounters in human stomach. The urease system is the basic process used to maintain periplasmic and cytoplasmic pH near neutrality when H. pylori is exposed to acidic condition. However, since the urea concentration in gastric juice is approximately 1 mM, considered possibly insufficient to ensure the survival of H. pylori, it is postulated that additional mechanisms of pH homeostasis may contribute to the acid adaptation in H. pylori. In order to identify the acid-related proteins other than the urease system we have compared the proteome profiles of H. pylori strain 26695 exposed to different levels of external pH (7.4, 6.0, 5.0, 4.0, 3.0, and 2.0) for 30 min in the absence of urea using 2-DE. Differentially expressed proteins were identified by MALDI-TOF-TOF-MS analysis, which turned out to be 36 different proteins. The functions of these proteins included ammonia production, molecular chaperones, energy metabolism, cell envelope, response regulator and some proteins with unknown function. SOM analysis indicated that H. pylori responds to acid stress through multi-mechanisms involving many proteins, which depend on the levels of acidity the cells encounter.

Two Forms of Vibrio vulnificus Metalloprotease VvpE are Secreted via the Type II General Secretion System: Jong Park , So-Yeon Ryu , Choon-Mee Kim , Sung-Heui Shin; J. Microbiol. 2008;46(3):338-343. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0058-6

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11 Citations

Abstract: Vibrio vulnificus has been known to secrete one form of metalloprotease VvpE (45 kDa) that is cleaved to 34 kDa-VvpE and 11 kDa-C-terminal propeptide via extracellular autoproteolysis. However, we found that extracellular secretion of both the 34 and 45 kDa forms of VvpE began in the early growth phase; moreover, 34 kDa-VvpE existed as the major form in V. vulnificus cell lysates and culture supernatants. In addition, extracellular secretion of both 34 and 45 kDa-VvpE was blocked by mutation of the pilD gene, which encodes for the type IV leader peptidase/N-methyltransferase of the type II general secretion system, and the blocked VvpE secretion was recovered by in trans-complementation of the wild-type pilD gene. These results indicate that 34 kDa-VvpE is the major form secreted along with 45 kDa-VvpE from the early growth phase via the PilD-mediated type II general secretion system.

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