Journal of Microbiology

Volume 45(4); August 2007

Review

Minireview] Alpine Microorganisms: Useful Tools for Low-Temperature Bioremediation: Rosa Margesin; J. Microbiol. 2007;45(4):281-285.; DOI: https://doi.org/2572 [pii]

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Abstract: Cold environments, including polar and alpine regions, are colonized by a wide diversity of microorganisms able to thrive at low temperatures. There is evidence of a wide range of metabolic activities in alpine cold ecosystems. Like polar microorganisms, alpine microorganisms play a key ecological role in their natural habitats for nutrient cycling, litter degradation, and many other processes. A number of studies have demonstrated the capacity of alpine microorganisms to degrade efficiently a wide range of hydrocarbons, including phenol, phenol-related compounds and petroleum hydrocarbons, and the feasibility of low-temperature bioremediation of European alpine soils by stimulating the degradation capacity of indigenous microorganisms has also been shown.

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

Resistance to Macrolide, Lincosamide and Streptogramin Antibiotics in Staphylococci Isolated in Istanbul, Turkey: Zerrin Aktas , Aslihan Aridogan , Cigdem Bal Kayacan , Derya Aydin; J. Microbiol. 2007;45(4):286-290.; DOI: https://doi.org/2571 [pii]

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Abstract: The purpose of this study was to investigate the prevalence and genetic mechanisms of erythromycin resistance in staphylococci. A total of 102 erythromycin resistant non-duplicate clinical isolates of staphylococci [78 coagulase negative stapylococci (CNS), 24 Staphylococcus aureus] were collected between October 2003 and August 2004 in Istanbul Faculty of Medicine in Turkey. The majority of the isolates were from blood and urine specimens. Antimicrobial susceptibilities were determined by the agar dilution procedure and the resistance phenotypes by the double disk induction test. A multiplex PCR was performed, using primers specific for erm(A), erm(B), erm(C), and msrA genes. Among the 78 CNS isolates, 57.8% expressed the MLSB-constitutive, 20.6% the MLSB-inducible, and 21.6% the MSB phenotypes. By PCR, 78.2% of these isolates harbored the erm(C) gene, 8.9% erm(A), 6.4% erm(B), and 11.5% msrA genes. In S. aureus, the constitutive MLSB (58.3%) was more common than the inducible phenotype (20.8%). erm(A) was detected in 50% and erm(C) in 62.5% of the isolates, while 37.5% contained both erm(A) and erm(C). erm(C)-associated macrolide resistance was the most prevalent in CNS, while erm(C) and erm(A, C) was the most prevalent in S. aureus.

Effect of Leuconostoc spp. on the Formation of Streptococcus mutans Biofilm: Mi-Sun Kang , In-Chol Kang , Seon-Mi Kim , Hyun-Chul Lee , Jong-Suk Oh; J. Microbiol. 2007;45(4):291-296.; DOI: https://doi.org/2570 [pii]

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Abstract: Insoluble glucans synthesized by Streptococcus mutans enhance the pathogenicity of oral biofilm by promoting the adherence and accumulation of cariogenic bacteria on the surface of the tooth. The objective of this study was to investigate the effect of Leuconostoc spp. on the in vitro formation of S. mutans biofilm. Three strains, Leuconostoc gelidum ATCC 49366, Leuconostoc mesenteroides ssp. cremoris ATCC 19254 and Leuconostoc mesenteroides ssp. mesenteroides ATCC 8293, were used in this study. They exhibited profound inhibitory effects on the formation of S. mutans biofilm and on the proliferation of S. mutans. The water-soluble polymers produced from sucrose were most strongly produced by L. gelidum, followed by L. mesenteroides ssp. cremoris and L. mesenteroides ssp. mesenteroides. The mean wet weights of the artificial biofilm of S. mutans were also significantly reduced as a result of the addition of the water-soluble polymers obtained from Leuconostoc cultures. According to the results of thin-layer chromatographic analysis, the hydrolysates of the water-soluble polymers produced by Leuconostoc were identical to those of dextran T-2000, forming predominately α-(1-6) glucose linkages. These results indicate that dextran-producing Leuconostoc strains are able to inhibit the formation of S. mutans biofilm in vitro.

Rapid Detection of Virulence Factors of Aeromonas Isolated from a Trout Farm by Hexaplex-PCR: In-Young Nam , Kiseong Joh; J. Microbiol. 2007;45(4):297-304.; DOI: https://doi.org/2569 [pii]

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Abstract: The detection of virulence factors of Aeromonas is a key component in determining potential pathogenicity because these factors act multifunctionally and multifactorially. In this study water samples were collected from a trout farm on a seasonal basis, and diseased fish and Aeromonas species were isolated and identified. For rapid detection of six virulence factors of isolated Aeromonas, a hexaplex-polymerase chain reaction (hexaplex-PCR) assay was used. The detected virulence factors include aerolysin (aer), GCAT (gcat), serine protease (ser), nuclease (nuc) lipase (lip) and lateral flagella (laf). The dominant strain found in our isolates was Aeromonas sobria, and the dominant virulence factors were aer and nuc for all seasons. We confirmed that A. sobria and two of the virulence genes (aer and nuc) are related. We proposed a method by which one can identify the major strains of Aeromonas: A. hydrophila, A. sobria, A. caviae, and A. veronii, using hexaplex-PCR.

Journal Article

Comparison of Cytokine and Nitric Oxide Induction in Murine Macrophages between Whole Cell and Enzymatically Digested Bifidobacterium sp. Obtained from Monogastric Animals: Dong Woon Kim , Sung Back Cho , Hyun Jeong Lee , Wan Tae Chung , Kyoung Hoon Kim , Jong Hwangbo , In Sik Nam , Young Il Cho , Mhan Pyo Yang , Il Byung Chung; J. Microbiol. 2007;45(4):305-310.; DOI: https://doi.org/2568 [pii]

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Abstract: The principal objective of this study was to compare the effects of whole and hydrolyzed cells (bifidobacteria) treated with gastrointestinal digestive enzymes on the activation of cloned macrophages. Seven different strains of Bifidobacterium obtained from swine, chickens, and rats, were digested with pepsin followed by pancreatin and the precipitate (insoluble fraction) and supernatant (soluble fraction) obtained via centrifugation. The RAW 264.7 murine macrophages were incubated with either whole cells, the precipitate, or supernatant at various concentrations. Pronounced increases in the levels of nitric oxide (NO), interleukin (IL)-1β, IL-6, IL-12, and tumor necrosis factor (TNF)-α were observed in the whole cells and precipitates, but these effects were less profound in the supernatants. The precipitates also evidenced a slight, but significant, inductive activity for NO and all tested cytokines, with the exception of TNF-α in the macrophage model as compared with the whole cells. By way of contrast, TNF-α production when cultured with whole cells (100 ng/ml) resulted in marked increases as compared with what was observed with the precipitates. The results of this study indicated, for the first time, that digested Bifidobacterium sp. can induce the production of NO and several cytokines in RAW 264.7 murine macrophage cells. In the current study, it was demonstrated that Bifidobacterium strains treated with digestive enzymes, as compared with whole cells, are capable of stimulating the induction of macrophage mediators, which reflects that they may be able to modulate the gastrointestinal immune functions of the host.

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

Phosphate and Carbon Source Regulation of Alkaline Phosphatase and Phospholipase in Vibrio vulnificus: Wan-Seok Oh , Young-Sun Im , Kyu-Young Yeon , Young-Jun Yoon , Jung-Wan Kim; J. Microbiol. 2007;45(4):311-317.; DOI: https://doi.org/2567 [pii]

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Abstract: In this study, the effects of phosphate concentration and carbon source on the patterns of alkaline phosphatase (APase) and phospholipase (PLase) expression in Vibrio vulnificus ATCC 29307 were assessed under various conditions. The activities of these enzymes were repressed by excess phosphate (4 mM) in the culture medium, but this repression was reversed upon the onset of phosphate starvation in low phosphate defined medium (LPDM) containing 0.2 mM of phosphate at approximately the end of the exponential growth phase. The expressions of the two enzymes were also influenced by different carbon sources, including glucose, fructose, maltose, glycerol, and sodium acetate at different levels. The APase activity was derepressed most profoundly in LPDM containing fructose as a sole carbon source. However, the repression/derepression of the enzyme by phosphate was not observed in media containing glycerol or sodium acetate. In LPDM-glycerol or sodium acetate, the growth rate was quite low. The highest levels of PLase activity were detected in LPDMsodium acetate, followed by LPDM-fructose. PLase was not fully repressed by high phosphate concentrations when sodium acetate was utilized as the sole carbon source. These results showed that multiple regulatory systems, including the phosphate regulon, may perform a function in the expression of both or either APase and PLC, in the broader context of the survival of V. vulnificus.

Isoforms of Glucose 6-Phosphate Dehydrogenase in Deinococcus radiophilus: Ji Youn Sung , Young Nam Lee; J. Microbiol. 2007;45(4):318-325.; DOI: https://doi.org/2566 [pii]

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Abstract: Glucose 6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in Deinococcus radiophilus, an extraordinarily UV-resistant bacterium, was investigated to gain insight into its resistance as it was shown to be involved in a scavenging system of superoxide (O2-1) and peroxide (O2-2) generated by UV and oxidative stresses. D. radiophilus possesses two G6PDH isoforms: G6PDH-1 and G6PDH-2, both showing dual coenzyme specificity for NAD and NADP. Both enzymes were detected throughout the growth phase; however, the substantial increase in G6PDH-1 observed at stationary phase or as the results of external oxidative stress indicates that this enzyme is inducible under stressful environmental conditions. The G6PDH-1 and G6PDH-2 were purified 122- and 44-fold (using NADP as cofactor), respectively. The purified G6PDH-1 and G6PDH-2 had the specific activity of 2,890 and 1,033 U/mg protein (using NADP as cofactor) and 3,078 and 1,076 U/mg protein (using NAD as cofactor), respectively. The isoforms also evidenced distinct structures; G6PDH-1 was a tetramer of 35 kDa subunits, whereas G6PDH-2 was a dimer of 60 kDa subunits. The pIs of G6PDH-1 and G6PDH-2 were 6.4 and 5.7, respectively. Both G6PDH-1 and G6PDH-2 were inhibited by both ATP and oleic acid, but G6PDH-1 was found to be more susceptible to oleic acid than G6PDH-2. The profound inhibition of both enzymes by β-naphthoquinone-4-sulfonic acid suggests the involvement of lysine at their active sites. Cu2+ was a potent inhibitor to G6PDH-2, but a lesser degree to G6PDH-1. Both G6PDH-1 and G6PDH-2 showed an optimum activity at pH 8.0 and 30°C.

Journal Article

The Physiological Role of CPR1 in Saccharomyces cerevisiae KNU5377 against Menadione Stress by Proteomics: Il Sup Kim , Hae Sun Yun , Sun Hye Kwak , Ing Nyol Jin; J. Microbiol. 2007;45(4):326-332.; DOI: https://doi.org/2565 [pii]

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Abstract: In order to understand the functional role of CPR1 in Saccharomyces cerevisiae KNU5377 with regard to its multi-tolerance characteristics against high temperatures, inorganic acids, and oxidative stress conditions, whole cellular proteins were analyzed via liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). This procedure was followed by two-dimensional (2-D) gel electrophoresis. Under menadione stress conditions, the 23 upregulated proteins were clearly identified only in the wildtype strain of KNU5377. Among the proteins, Sod1p, Tsa1p, Ahp1, Cpr1p, Cpr3, Ssb2p, and Hsp12p were identified as components of antioxidant systems or protein-folding related systems. The CPR1 protein could not be completely detected in the cpr1Δ mutant of KNU5377 and the other upregulated proteins in the wild-type strain evidenced a clear correlation with the results of immunoblot analysis. Moreover, a reduction in growth patterns (about 50%) could be observed in the cpr1Δ mutant, as compared with that of the wild-type strain under mild MD stress conditions. These results indicate that the upregulation of CPR1 may contribute to tolerance against MD as an inducer of oxidative stress.

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

Purification and Characterization of an Intracellular NADH: Quinone Reductase from Trametes versicolor: Sang-Soo Lee , Dong-Soo Moon , Hyoung T. Choi , Hong-Gyu Song; J. Microbiol. 2007;45(4):333-338.; DOI: https://doi.org/2564 [pii]

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Abstract: Intracellular NADH:quinone reductase involved in degradation of aromatic compounds including lignin was purified and characterized from white rot fungus Trametes versicolor. The activity of quinone reductase was maximal after 3 days of incubation in fungal culture, and the enzyme was purified to homogeneity using ion-exchange, hydrophobic interaction, and gel filtration chromatographies. The purified enzyme has a molecular mass of 41 kDa as determined by SDS-PAGE, and exhibits a broad temperature optimum between 20-40°C, with a pH optimum of 6.0. The enzyme preferred FAD as a cofactor and NADH rather than NADPH as an electron donor. Among quinone compounds tested as substrate, menadione showed the highest enzyme activity followed by 1,4-benzoquinone. The enzyme activity was inhibited by CuSO4, HgCl2, MgSO4, MnSO4, AgNO3, dicumarol, KCN, NaN3, and EDTA. Its Km and Vmax with NADH as an electron donor were 23 μM and 101 mM/mg per min, respectively, and showed a high substrate affinity. Purified quinone reductase could reduce 1,4-benzoquinone to hydroquinone, and induction of this enzyme was higher by 1,4-benzoquinone than those of other quinone compounds.

Screening of Genes Related to Methylglyoxal Susceptibility: Insook Kim , Joonho Kim , Bumchan Min , Changhan Lee , Chankyu Park; J. Microbiol. 2007;45(4):339-343.; DOI: https://doi.org/2563 [pii]

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Abstract: Methylglyoxal (MG) is a reactive metabolite known to accumulate in certain physiological conditions. We attempted to isolate genes associated with this metabolite by genome-wide mutagenesis with TnphoA derivative. After screening on methylglyoxal-containing plate, we obtained insertions in three different genes, ydbD, yjjQ, and yqiI, which gave rise to reproducible MG-sensitive phenotypes in glyoxalase-deficient strain. In addition to its MG sensitivity, the insertion in yqiI exhibited an impaired motility resulting from a reduced flagellar expression.

Schizosaccharomyces pombe nup97, which Genetically Interacts with mex67, is Essential for Growth and Involved in mRNA Export: Hyun Jin Cho , Duk Kyung Hwang , Sun Im Jung , Jin Ho Yoon; J. Microbiol. 2007;45(4):344-349.; DOI: https://doi.org/2562 [pii]

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Abstract: We have isolated previously three synthetic lethal mutants in Schizosaccharomyces pombe, which genetically interact with mex67, in order to identify the genes involved in mRNA export. A novel nup97 gene was isolated by complementation of the growth defect in one of the synthetic lethal mutants, SLMex3. The nup97 gene contains one intron and encodes an 851 amino-acid protein that is similar to nucleoporins, Npp106p in S. pombe and Nic96p in Saccharomyces cerevisiae. The nup97 gene is essential for vegetative growth, and nup97 null mutant harboring pREP41X-Nup97 showed poly(A)+ RNA export defect when expression of nup97 is repressed in the presence of thiamine. These results suggest that nup97 is involved in mRNA export from the nucleus to cytoplasm.

Effect of Saliva miltiorrhiza Bunge on Antimicrobial Activity and Resistant Gene Regulation against Methicillin-Resistant Staphylococcus aureus (MRSA): Ji-Won Lee , Young-Ju Ji , Syng-Ook Lee , In-Seon Lee; J. Microbiol. 2007;45(4):350-357.; DOI: https://doi.org/2561 [pii]

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Abstract: This study was conducted in an effort to evaluate the antimicrobial activity and antibiotic-resistant gene regulation from Saliva miltiorrhiza Bunge on methicillin-resistant Staphylococcus aureus (MRSA). A variety of solvent fractions and methanol extracts of S. miltiorrhiza Bunge were tested in order to determine its antimicrobial activities against S. aureus and MRSA. As a result, the hexane fraction of S. miltiorrhiza Bunge evidenced the highest levels of antimicrobial activity against S. aureus and MRSA. The MICs of the hexane fraction against various MRSA specimens were 64<MICs≤128 μg/ml. The hexane fraction evidenced inhibitory effects superior to those of the chloroform fraction. The results showed inhibition zones of hexane (16 mm) and chloroform (14 mm) fractions against MRSA KCCM 40511 at 1,000 μg/disc. The hexane and chloroform fractions inhibited the expression of the resistant genes, mecA, mecR1, and femA in mRNA. Moreover, the results of Western blotting assays indicated that the hexane and chloroform fractions inhibited the expression of the resistant protein, PBP2a. These results reveal that the hexane and chloroform fractions of S. miltiorrhiza Bunge may prove to be a valuable choice for studies targeted toward the development of new antimicrobial agents.

Molecular Characterization of Pseudomonas aeruginosa Isolates Resistant to All Antimicrobial Agents, but Susceptible to Colistin, in Daegu, Korea: Yoo Chul Lee , Byung Jun Ahn , Jong Sook Jin , Jung Uk Kim , Sang Hwa Lee , Do Young Song , Won Kil Lee , Je Chul Lee; J. Microbiol. 2007;45(4):358-363.; DOI: https://doi.org/2560 [pii]

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Abstract: Multi-drug resistant Pseudomonas aeruginosa has been implicated in a variety of serious therapeutic problems in clinical environments. Among the 968 P. aeruginosa isolates obtained from two hospitals in Daegu, Korea, we acquired 17 isolates that were resistant to all available tested antimicrobial agents, with the exception of colistin (colistin-only sensitive). We characterized the antimicrobial susceptibilities, metallo-β-lactamases, and epidemiological relatedness among the colistin-only sensitive P. aeruginosa isolates. All colistin-only sensitive isolates were positive in the modified Hodge test and imipenem-EDTA synergy test, thereby indicating the production of metallo-β-lactamases. 11 isolates from the secondary hospital and six isolates from the tertiary teaching hospital harbored blaVIM-2 and blaIMP-1, respectively. The pulsed-field gel electrophoretic analysis of the SpeI-digested DNA from P. aeruginosa isolates indicated that two different clones of colistin-only sensitive P. aeruginosa originated from each hospital, and had spread within the hospital environment. Overall, colistin-only sensitive P. aeruginosa was detected in Korea for the first time, but no pan-drug resistant bacteria were identified. Nationwide surveillance is required in order to monitor the emergence of colistin-only sensitive or pan-drug resistant bacteria.

Immunological Roles of Pasteurella multocida Toxin (PMT) Using a PMT Mutant Strain: Tae Jung Kim , Nguyen Tat Toan , Eun Jin Jang , Bock Gie Jung , Jae Il Lee , Bong Joo Lee; J. Microbiol. 2007;45(4):364-366.; DOI: https://doi.org/2559 [pii]

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Abstract: The immunological role of the Pasteurella multocida toxin (PMT) in mice was examined using a PMT mutant strain. After a nasal inoculation, the mutant strain failed to induce interstitial pneumonia. Moreover, PMT had no significant effect on the populations of CD4+, CD8+, CD3+, and CD19+ immunocytes in blood or on the populations of CD4+ and CD8+ splenocytes (P<0.01). However, there was a significant increase in the total number of cells in the BAL samples obtained from the wild-type P. multocida-inoculated mice. On the other hand, the level of IL-1 expression decreased when the macrophages from the bronchio-alveolar lavage were stimulated with PMT. Overall, PMT appears to play some role (stimulating and/or inhibiting) in the immunological responses but further studies will be required to confirm this.

Diversity of Microorganisms in Decaying Maize Stalks Revealed by a Molecular Method: Ming-Xia Yang , Han-Bo Zhang; J. Microbiol. 2007;45(4):367-370.; DOI: https://doi.org/2558 [pii]

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Abstract: Microbial diversity in decaying maize stalk was characterized by constructing and analyzing rRNA gene clone library. Total 47 OTUs were obtained from 82 bacterial clones, including Proteobacteria (64.6%), Actinobacteria (30.5%), Bacteroidetes (2.4%) and Firmicutes (2.4%). Most proteobacterial clones were members of Rhizobium, Pseudomonas and Stenotrophomonas. Eighty-four percent of Actinobacteria was related to Microbacterium. Only 14 OTUs were identified from 124 fungal clones, including Ascomycota (88%) and Basidiomycota (12%). Sixty percent of Ascomycota were members of Eupenicillium and Paecilomyces but all Basidiomycota were close to Kurtzmanomyces nectairei.

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