Journal of Microbiology

Volume 55(2); February 2017

Review

MINIREVIEW] Dengue and Zika viruses: lessons learned from the similarities between these Aedes mosquito-vectored arboviruses: San Suwanmanee , Natthanej Luplertlop; J. Microbiol. 2017;55(2):81-89. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6494-4

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41 Citations

Abstract: The currently spreading arbovirus epidemic is having a severe impact on human health worldwide. The two most common flaviviruses, dengue virus (DENV) and Zika virus (ZIKV), are transmitted through the same viral vector, Aedes spp. mosquitoes. Since the discovery of DENV in 1943, this virus has been reported to cause around 390 million human infections per year, approximately 500,000 of which require hospitalization and over 20,000 of which are lethal. The present DENV epidemic is primarily concentrated in Southeast Asia. ZIKV, which was discovered in 1952, is another important arthropod-borne flavivirus. The neurotropic role of ZIKV has been reported in infected newborns with microcephaly and in adults with Guillain-Barre syndrome. Despite DENV and ZIKV sharing the same viral vector, their complex pathogenic natures are poorly understood, and the infections they cause do not have specific treatments or effective vaccines. Therefore, this review will describe what is currently known about the clinical characteristics, pathogenesis mechanisms, and transmission of these two viruses. Better understanding of the interrelationships between DENV and ZIKV will provide a useful perspective for developing an effective strategy for controlling both viruses in the future.

Journal Articles

Cyclobacterium sediminis sp. nov. isolated from a sea cucumber aquaculture farm and emended description of the genus Cyclobacterium: Seyeon Shin , Hyung-Yeel Kahng; J. Microbiol. 2017;55(2):90-95. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6484-6

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6 Citations

Abstract: An aerobic, Gram-negative bacterium, designated strain SD70T, was isolated from sea cucumber aquaculture farm sediment in Taean, Korea, and its taxonomic status was established by undertaking a polyphasic study. Cells of strain SD70T were non-motile, catalase-, and oxidase-positive, nonspore- forming, and horseshoe-shaped. Optimal growth was observed under 25–30°C, pH 7.0–8.0, and 3.0–5.0% (w/v) NaCl conditions. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain SD70T fell within an evolutionary group comprising species of the genus Cyclobacterium. Strain SD70T shared 92.1–98.5% 16S rRNA sequence similarity values with the type strains of species of the genus Cyclobacterium. Relatively low levels of DNA-DNA relatedness were found between strain SD70T and C. marinum DSM 745T (40.2%) and C. amurskyense KMM 6143T (15.8%). The predominant cellular fatty acids were iso-C15:0 (32.1%), and anteiso-C15:0 (9.1%). Menaquinone MK-7 was the only respiratory quinone. The G+C content of the genomic DNA was 36 mol%. The polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and seven unidentified lipids. On the basis of phenotypic and genotypic data, strain SD70T represents a novel species of the genus Cyclobacterium, for which the name Cyclobacterium sediminis sp. nov. is proposed. An emended description of the genus Cyclobacterium is also provided.

Candida krusei isolated from fruit juices ultrafiltration membranes promotes colonization of Escherichia coli O157:H7 and Salmonella enterica on stainless steel surfaces: María Clara Tarifa , Jorge Enrique Lozano , Lorena Inés Brugnoni; J. Microbiol. 2017;55(2):96-103. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6300-3

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9 Citations

Abstract: To clarify the interactions between a common food spoilage yeast and two pathogenic bacteria involved in outbreaks associated with fruit juices, the present paper studies the effect of the interplay of Candida krusei, collected from UF membranes, with Escherichia coli O157:H7 and Salmonella enterica in the overall process of adhesion and colonization of abiotic surfaces. Two different cases were tested: a) co-adhesion by pathogenic bacteria and yeasts, and b) incorporation of bacteria to pre-adhered C. krusei cells. Cultures were made on stainless steel at 25°C using apple juice as culture medium. After 24 h of co-adhesion with C. krusei, both E. coli O157:H7 and S. enterica increased their counts 1.05 and 1.11 log CFU cm2, respectively. Similar increases were obtained when incorporating bacteria to pre-adhered cells of Candida. Nevertheless C. krusei counts decreased in both experimental conditions, in a) 0.40 log CFU cm2 and 0.55 log CFU cm2 when exposed to E. coli O157:H7 and S. enterica and in b) 0.18 and 0.68 log CFU cm2, respectively. This suggests that C. krusei, E. coli O157:H7, and S. enterica have a complex relationship involving physical and chemical interactions on food contact surfaces. This study supports the possibility that pathogen interactions with members of spoilage microbiota, such as C. krusei, might play an important role for the survival and dissemination of E. coli O157:H7 and Salmonella enterica in food-processing environments. Based on the data obtained from the present study, much more attention should be given to prevent the contamination of these pathogens in acidic drinks.

Optimization of Enterobacter cloacae (KU923381) for diesel oil degradation using Response Surface Methodology (RSM): Sugumar Ramasamy , Arumugam Arumugam , Preethy Chandran; J. Microbiol. 2017;55(2):104-111. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6265-2

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45 Citations

Abstract: Efficiency of Enterobacter cloacae KU923381 isolated from petroleum hydrocarbon contaminated soil was evaluated in batch culture and bioreactor mode. The isolate were screened for biofilm formation using qualitative and quantitative assays. Response surface methodology (RSM) was used to study the effect of pH, temperature, glucose concentration, and sodium chloride on diesel degradation. The predicted values for diesel oil degradation efficiency by the statistical designs are in a close agreement with experimental data (R2 = 99.66%). Degradation efficiency is increased by 36.78% at pH = 7, temperature = 35°C, glucose = 5%, and sodium chloride concentration = 5%. Under the optimized conditions, the experiments were performed for diesel oil degradation by gas chromatographic mass spectrometric analysis (GC-MS). GC-MS analysis confirmed that E. cloacae had highly degrade hexadecane, heptadecane, tridecane, and docosane by 99.71%, 99.23%, 99.66%, and 98.34% respectively. This study shows that rapid bioremoval of hydrocarbons in diesel oil is acheived by E. cloacae with abet of biofilm formation. The potential use of the biofilms for preparing trickling filters (gravel particles) for the degradation of hydrocarbons from petroleum wastes before their disposal in the open environment is highly suggested. This is the first successful attempt for artificially establishing petroleum hydrocarbon degrading bacterial biofilm on solid substrates in bioreactor.

The protein and neutral lipid composition of lipid droplets isolated from the fission yeast, Schizosaccharomyces pombe: Alex Meyers , Karuna Chourey , Taylor M. Weiskittel , Susan Pfiffner , John R. Dunlap , Robert L. Hettich , Paul Dalhaimer; J. Microbiol. 2017;55(2):112-122. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6205-1

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15 Citations

Abstract: Lipid droplets consist of a core of neutral lipids surrounded by a phospholipid monolayer with bound proteins. Much of the information on lipid droplet function comes from proteomic and lipodomic studies that identify the components of droplets isolated from organisms throughout the phylogenetic tree. Here, we add to that important inventory by reporting lipid droplet factors from the fission yeast, Schizosaccharomyces pombe. Unique to this study was the fact that cells were cultured in three different environments: 1) late log growth phase in glucose-based media, 2) stationary phase in glucosebased media, and 3) late log growth phase in media containing oleic acid. We confirmed colocalization of major factors with lipid droplets using live-cell fluorescent microscopy. We also analyzed droplets from each of the three conditions for sterol ester (SE) and triacylglycerol (TAG) content, along with their respective fatty acid compositions. We identified a previously undiscovered lipid droplet protein, Vip1p, which affects droplet size distribution. The results provide further insight into the workings of these ubiquitous organelles.

HST1 increases replicative lifespan of a sir2Δ mutant in the absence of PDE2 in Saccharomyces cerevisiae: Woo Kyu Kang , Mayur Devare , Jeong-Yoon Kim; J. Microbiol. 2017;55(2):123-129. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6535-z

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7 Citations

Abstract: Silent information regulator 2 (Sir2), which is the founding member of the sirtuin family of proteins, is a pro-longevity factor for replicative lifespan (RLS) in Saccharomyces cerevisiae. Sir2 is required for transcriptional silencing at mating type loci, telomeres, and rDNA loci. Sir2 also represses transcription of highly expressed growth-related genes, such as PMA1 and some ribosomal protein genes. Although the Sir2 paralogues Hst1, Hst2, Hst3, and Hst4 occur in S. cerevisiae, none of them could replace the transcriptional regulation of PMA1 by Sir2 in the wild type. In this study, we demonstrate that Hst1, the closest Sir2 paralogue, deacetylates the acetylated lysine 16 of histone H4 (H4K16Ac) and represses PMA1 transcription in the sir2Δ pde2Δ mutant. We further show that Hst1 plays a role in extending the RLS of the sir2Δ pde2Δ mutant. Collectively, our results suggest that Hst1 can substitute for Sir2 by deacetylating H4K16Ac only in the sir2Δ pde2Δ.

Contribution of EmrAB efflux pumps to colistin resistance in Acinetobacter baumannii: Ming-Feng Lin , Yun-You Lin , Chung-Yu Lan; J. Microbiol. 2017;55(2):130-136. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6408-5

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71 Citations

Abstract: Efflux pumps play an important role in antimicrobial resistance for Acinetobacter baumannii. However, the function of the Emr pump system and the relationship between Emr and drug resistance has not been characterized in A. baumannii. In this study, four possible groups of emr-like genes were found by searching a genome database. Among them, A1S_ 1772 (emrB) and A1S_1773 (emrA) were demonstrated to be co-transcribed as a single operon. Moreover, during osmotic stress, A1S_1772 showed the largest change in gene expression compared to the other emrB-like genes, and deletion of A1S_1772 (AB ΔemrB) significantly slowed cell growth in 20% sucrose. Using a phenotypic microarray analysis, the AB ΔemrB mutant was more susceptible to colistin and nafcillin, paromomycin, spiramycin, and D,L-serine hydroxmate than the wild type. The spot assay, time kill assay and minimal inhibition concentration determination also indicated that the wild type could tolerate colistin better than the AB ΔemrB mutant. Finally, the increased expression levels of all emrBlike genes, including A1S_0775, A1S_0909, A1S_1772, and A1S_1799, in colistin resistance-induced A. baumannii further supported the possible involvement of the emrB genes in A. baumannii colistin resistance. Together, the Emr pump systems in A. baumannii contribute to adaptation to osmotic stress and resistance to colistin.

Oxidative stress response of Deinococcus geothermalis via a cystine importer: Minwook Kim , Sunwook Jeong , Sangyong Lim , Jeonggu Sim , Ho-Gun Rhie , Sung-Jae Lee; J. Microbiol. 2017;55(2):137-146. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6382-y

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11 Citations

Abstract: A cystine-dependent anti-oxidative stress response is characterized in Deinococcus geothermalis for the first time. Nevertheless, the same transcriptional directed Δdgeo_1985F mutant strain was revealed to have an identical phenotype to the wild-type strain, while the reverse transcriptional directed Δdgeo_1985R mutant strain was more resistant to oxidative stress at a certain concentration of H2O2 than the wild-type strain. The wild-type and mutant strains expressed equal levels of superoxide dismutase and catalase under H2O2-induced stress. Although the expression levels of the general DNAdamage response-related genes recA, pprA, ddrA, and ddrB were up-regulated by more than five-fold in the wild-type strain relative to the Δdgeo_1985R mutant strain, the mutant strain had a higher survival rate than the wild-type under H2O2 stress. The Δdgeo_1985R mutant strain highly expressed a cystine-transporter gene (dgeo_1986), at levels 150-fold higher than the wild-type strain, leading to the conclusion that this cystine transporter might be involved in the defensive response to H2O2 stress. In this study, the cystine transporter was identified and characterized through membrane protein expression analysis, a cystine-binding assay, and assays of intracellular H2O2, cysteine, and thiol levels. The genedisrupted mutant strain of the cystine importer revealed high sensitivity to H2O2 and less absorbed cystine, resulting in low concentrations of total thiol. Thus, the absorbed cystine via this cystine-specific importer may be converted into cysteine, which acts as a primitive defense substrate that non-enzymatically scavenges oxidative stress agents in D. geothermalis.

Heterologous expression and enzymatic characterization of γ-glutamyltranspeptidase from Bacillus amyloliquefaciens: Jung-Min Lee , Jaejung Lee , Gyeong-Hwa Nam , Byung-Sam Son , Myoung-Uoon Jang , So-Won Lee , Byung-Serk Hurh , Tae-Jip Kim; J. Microbiol. 2017;55(2):147-152. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6638-6

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16 Citations

Abstract: γ-Glutamyltranspeptidase (GGT) catalyzes the cleavage of γ- glutamyl compounds and the transfer of γ-glutamyl moiety to water or to amino acid/peptide acceptors. GGT can be utilized for the generation of γ-glutamyl peptides or glutamic acid, which are used as food taste enhancers. In the present study, Bacillus amyloliquefaciens SMB469 with high GGT activity was isolated from Doenjang, a traditional fermented soy food of Korea. The gene encoding GGT from B. amyloliquefaciens SMB469 (BaGGT469) was cloned from the isolate, and heterologously expressed in E. coli and B. subtilis. For comparison, three additional GGT genes were cloned from B. subtilis 168, B. licheniformis DSM 13, and B. amyloliquefaciens FZB42. The BaGGT469 protein was composed of 591 amino acids. The final protein comprises two separate polypeptide chains of 45.7 and 19.7 kDa, generated via autocatalytic cleavage. The specific activity of BaGGT469 was determined to be 17.8 U/mg with γ-L-glutamyl-p-nitroanilide as the substrate and diglycine as the acceptor. GGTs from B. amyloliquefaciens showed 1.4- and 1.7-fold higher transpeptidase activities than those from B. subtilis and B. licheniformis, respectively. Especially, recombinant B. subtilis expressing BaGGT469 demonstrated 11- and 23-fold higher GGT activity than recombinant E. coli and the native B. amyloliquefaciens, respectively, did. These results suggest that BaGGT469 can be utilized for the enzymatic production of various γ- glutamyl compounds.

Phenotypic and genotypic correlates of daptomycin-resistant methicillin-susceptible Staphylococcus aureus clinical isolates: Kyoung-Mi Kang , Nagendra N. Mishra , Kun Taek Park , Gi-Yong Lee , Yong Ho Park , Arnold S. Bayer , Soo-Jin Yang; J. Microbiol. 2017;55(2):153-159. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6509-1

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24 Citations

Abstract: Daptomycin (DAP) has potent activity in vitro and in vivo against both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. DAP-resistance (DAP-R) in S. aureus has been mainly observed in MRSA strains, and has been linked to single nucleotide polymorphisms (SNPs) within the mprF gene leading to altered cell membrane (CM) phospholipid (PL) profiles, enhanced positive surface charge, and changes in CM fluidity. The current study was designed to delineate whether these same genotypic and phenotypic perturbations are demonstrated in clinically-derived DAP-R MSSA strains. We used three isogenic DAP-susceptible (DAP-S)/DAP-R strainpairs and compared: (i) presence of mprF SNPs, (ii) temporal expression profiles of the two key determinants (mprF and dltABCD) of net positive surface charge, (iii) increased production of mprF-dependent lysinylated-phosphatidylglycerol (L-PG), (iv) positive surface charge assays, and (v) susceptibility to cationic host defense peptides (HDPs) of neutrophil and platelet origins. Similar to prior data in MRSA, DAP-R (vs DAP-S) MSSA strains exhibited hallmark hot-spot SNPs in mprF, enhanced and dysregulated expression of both mprF and dltA, L-PG overproduction, HDP resistance and enhanced positive surface charge profiles. However, in contrast to most DAP-R MRSA strains, there were no changes in CM fluidity seen. Thus, charge repulsion via mprF- and dlt-mediated enhancement of positive surface charge may be the main mechanism to explain DAP-R in MSSA strains.

Published Erratum

Erratum] Inhibitory effects of bee venom and its components against viruses in vitro and in vivo: Md Bashir Uddin , Byeong-Hoon Lee , Chamilani Nikapitiya , Jae-Hoon Kim , Tae-Hwan Kim , Hyun-Cheol Lee , Choul Goo Kim , Jong-Soo Lee , Chul-Joong Kim; J. Microbiol. 2017;55(2):160-160.; DOI: https://doi.org/10.1007/s12275-017-0668-y

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Abstract: In the article by Uddin et al. published in Journal of Microbiology 2016; 54, 853–866, the Protocol number on page 856 and 865 should be corrected as below.

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