Journal of Microbiology

Volume 53(2); February 2015

Review

Minireview] The molecular mechanism of azole resistance in Aspergillus fumigatus: from bedside to bench and back: Xiaolei Wei , Yuanwei Zhang Zhang , Ling Lu; J. Microbiol. 2015;53(2):91-99. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-5014-7

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26 Citations

Abstract: The growing use of immunosuppressive therapies has resulted in a dramatic increased incidence of invasive fungal infections (IFIs) caused by Aspergillus fumigatus, a common pathogen, and is also associated with a high mortality rate. Azoles are the primary guideline-recommended therapy agents for first-line treatment and prevention of IFIs. However, increased azole usage in medicinal and agricultural settings has caused azole-resistant isolates to repeatedly emerge in the environment, resulting in a significant threat to human health. In this review, we present and summarize current research on the resistance mechanisms of azoles in A. fumigatus as well as efficient susceptibility testing methods. Moreover, we analyze and discuss the putative clinical (bedside) indication of these findings from bench work.

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

Negative regulation of the vacuole-mediated resistance to K+ stress by a novel C2H2 zinc finger transcription factor encoded by aslA in Aspergillus nidulans: Dong Soo Park , Yeong Man Yu , Yong Jin Kim , Pil Jae Maeng; J. Microbiol. 2015;53(2):100-110. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4701-8

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Abstract: In fungi and plants, vacuoles function as a storage and sequestration vessel for a wide variety of ions and are responsible for cytosolic ion homeostasis and responses to ionic shock. In the filamentous fungus Aspergillus nidulans, however, little is known about the molecular genetic mechanisms of vacuolar biogenesis and function. In the present study, we analyzed the function of the aslA gene (AN5583) encoding a novel C2H2-type zinc finger transcription factor (TF) in relation to K+ stress resistance, vacuolar morphology, and vacuolar transporters. The mutant lacking aslA showed increased mycelial growth and decreased branching at high K+ concentrations. Deletion of aslA also caused elevated K+ stress-inducible expression of the genes, nhxA (AN2288), vnxA (AN6986), and vcxA (AN0471), encoding putative endosomal and vacuolar cation/H+ exchangers, as well as cpyA and vpsA genes encoding the proteins involved in vacuolar biogenesis. Interestingly, vacuolar fragmentation induced by K+ stress was alleviated by aslA deletion, resulting in persistence of unfragmented vacuoles. In the presence of bafilomycin, an inhibitor of vacuolar H+-ATPase, the mutant phenotype was suppressed in terms of growth rates and vacuolar morphology. These results together suggest that the C2H2- type zinc finger TF AslA attenuates the K+ stress-inducible expression of the genes encoding the ion pumps involved in vacuolar sequestration of K+ ions powered by vacuolar H+- ATPase, as well as the proteins that function in vacuolar biogenesis.

Deletion analysis of LSm, FDF, and YjeF domains of Candida albicans Edc3 in hyphal growth and oxidative-stress response: Eung-Chul Kim , Jinmi Kim; J. Microbiol. 2015;53(2):111-115. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4727-y

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Abstract: Candida albicans is an opportunistic fungal pathogen whose responses to environmental changes are associated with the virulence attributes. Edc3 is known to be an enhancer of the mRNA decapping reactions and a scaffold protein of cytoplasmic processing bodies (P-bodies). Recent studies of C. albicans Edc3 suggested its critical roles in filamentous growth and stress-induced apoptotic cell death. The edc3/edc3 deletion mutant strain showed increased cell survival and less ROS accumulation upon treatment with hydrogen peroxide. To investigate the diverse involvement of Edc3 in the cellular processes, deletion mutations of LSm, FDF, or YjeF domain of Edc3 were constructed. The edc3-LSmΔ or edc3-YjeFΔ mutation showed the filamentation defect, resistance to oxidative stress, and decreased ROS accumulation. In contrast, the edc3-FDFΔ mutation exhibited a wild-type level of filamentous growth and a mild defect in ROS accumulation. These results suggest that Lsm and YjeF domains of Edc3 are critical in hyphal growth and oxidative stress response.

Journal Article

Anti protein A antibody-gold nanorods conjugate: a targeting agent for selective killing of methicillin resistant Staphylococcus aureus using photothermal therapy method: Rasoul Shokri , Mojtaba Salouti , Rahim Sorouri Zanjani; J. Microbiol. 2015;53(2):116-121. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4519-4

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24 Citations

Abstract: The high prevalence of methicillin resistant Staphylococcus aureus (MRSA) and developing resistance to antibiotics requires new approaches for treatment of infectious diseases due to this bacterium. In this study, we developed a targeting agent for selective killing of MRSA using photothermal therapy method based on anti protein A antibody and gold nanorods (GNRs). Polystyrene sulfonate (PSS) coated GNRs were conjugated with anti protein A antibody. The FT-IR and UV-vis analyses approved the formation of anti protein A antibody-gold nanorods conjugate. In vitro study of photothermal therapy showed 82% reduction in the MRSA cells viability which was significantly greater than the ablation effect of free GNRs and laser alone. Significant accumulation of anti protein A antibody-GNRs in the infected muscle in comparison with normal muscle approved the targeting ability of new agent. In vivo study of photothermal therapy resulted in a significant reduction (73%) in the bacterial cells viability in the infected mouse model. These results demonstrated the ability of anti protein A antibody-GNRs conjugate in combination with NIR laser energy for selective killing of MRSA in mouse model.

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

The effects of fluctuating culture temperature on stress tolerance and antioxidase expression in Esteya vermicola: Yun-bo Wang , Wen-xing Pang , Xiao-na Yv , Jing-jie Li , Yong-an Zhang , Chang-keun Sung; J. Microbiol. 2015;53(2):122-126. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4529-2

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Abstract: The endoparasitic nematophagous fungus, Esteya vermicola, has shown great potential as a biological control agent against the pine wood nematode, Bursaphelenchus xylophilus. Fluctuating culture temperatures can affect fungal yields and fungal tolerance to desiccation, UV radiation, H2O2, and heat stress, as well as antioxidase expression. To explore these effects, E. vermicola cultured under five temperature ranges, 26oC, 15-26oC, 26-35oC, 20-30oC, and 15-35oC, were compared. The cultures grown at lower temperatures showed better growth, stronger tolerance to desiccation, UV, and H2O2 stresses, and increased catalase expression, However, these cultures also showed weaker heat stress tolerance and lower superoxide dismutase expression than the higher-temperature cultures. In particular, the E. vermicola cultured at 20-30oC, i.e., fluctuating in a narrow range around the optimal temperature, showed the best performance. Therefore, for production in practical applications, this narrowly fluctuating, moderate temperature appears to be optimal for yield and stress tolerance in E. vermicola.

Benzaldehyde as an insecticidal, antimicrobial, and antioxidant compound produced by Photorhabdus temperata M1021: Ihsan Ullah , Abdul Latif Khan , Liaqat Ali , Abdur Rahim Khan , Muhammad Waqas , Javid Hussain , In-Jung Lee , Jae-Ho Shin; J. Microbiol. 2015;53(2):127-133. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4632-4

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101 Citations

Abstract: The Photorhabdus temperata M1021 secretes toxic compounds that kill their insect hosts by arresting immune responses. Present study was aimed to purify the insecticidal and antimicrobial compound(s) from the culture extract of P. temperata M1021 through bioassay guided fractionation. An ethyl acetate (EtOAc) extract of the P. temperata M1021 exhibited 100% mortality in Galleria mellonella larvae within 72 h. In addition, EtOAc extract and bioactive compound 1 purified form the extract through to column chromatography, showed phenol oxidase inhibition up to 60% and 80% respectively. The analysis of 1H and 13C NMR spectra revealed the identity of pure compound as "benzaldehyde". The benzaldehyde showed insecticidal activity against G. mellonella in a dose-dependent manner and 100% insect mortality was observed at 108 h after injection of 8 mM benzaldehyde. In a PO inhibition assay, 4, 6, and 8 mM concentrations of benzaldehyde were found to inhibit PO activity about 15%, 42%, and 80% respectively. In addition, nodule formation was significantly (P < 0.05) inhibited by 4, 6, and 8 mM of benzaldehyde as compare to control. Moreover, benzaldehyde was found to have great antioxidant activity and maximum antioxidant activity was 52.9% at 8 mM benzaldehyde as compare to control. Antimicrobial activity was assessed by MIC values ranged from 6 mM 10 mM for bacterial strains and 8 mM to 10 mM for fungal strains. The
results
suggest that benzaldehyde could be applicable for developing novel insecticide for agriculture use.

Transcription level analysis of intracellular Burkholderia pseudomallei illustrates the role of BPSL1502 during bacterial interaction with human lung epithelial cells: Teerasit Techawiwattanaboon , Tanachaporn Bartpho , Rasana Wongratanacheewin Sermswan , Sorujsiri Chareonsudjai; J. Microbiol. 2015;53(2):134-140. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4522-9

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Abstract: Melioidosis caused by Burkholderia pseudomallei is a globally important disease of increasing concern according to high
case
-fatality rate and epidemic spreading. The ability of B. pseudomallei to attach and invade host cells and subsequently survive intracellularly has stimulated many questions concerning the comprehension of bacterial pathogenesis progression. Transcription levels of intracellular B. pseudomallei genes in human lung epithelial cells were therefore analyzed using bioinformatic tools, RT-PCR and real time RT-PCR. Here, it is reported that the identification of bpsl1502, encoding B. pseudomallei SurE (stationary phase survival protein E) located in a global transcriptional regulation operon was accomplished. The up-regulation of B. pseudomallei SurE was demonstrated during intracellular survival of A549 cells at 12, 18, and 24 h post-infection. To investigate the role of this protein, a B. pseudomallei SurE defective mutant was constructed. The invasion and initial survival of the SurE mutants within the A549 cells were impaired. There was no difference, however, between the growth of B. pseudomallei SurE mutant as compared to the wild type in Luria-Bertani culture. These data suggest that SurE may assist B. pseudomallei host cells invade and facilitate early intracellular infection but is not crucial during the stationary growth phase. The identification of B. pseudomallei SurE provides more information of bacterial strategy during an early step of the pathogenesis process of melioidosis.

Identification of tyrosine 71 as a critical residue for the cytotoxic activity of Clostridium perfringens epsilon toxin towards MDCK cells: Zhigang Jiang , Jitao Chang , Fang Wang , Li Yu; J. Microbiol. 2015;53(2):141-146. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4523-8

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Abstract: Clostridium perfringens epsilon toxin (Etx) is an extremely potent toxin, causing fatal enterotoxaemia in many animals. Several amino acids in domains I and II have been proposed to be critical for Etx to interact with MDCK cells. However, the critical amino acids in domain III remain undefined. Therefore, we assessed the effects of aromatic amino acids in domain III on Etx activity in this study. All of the results indicated that Y71 was critical for the cytotoxic activity of Etx towards MDCK cells, and this activity was dependent on the existence of an aromatic ring residue in position 71. Additionally, mutations in Y71 did not affect the binding of Etx to MDCK cells, indicating that Y71 is not a receptor binding site for Etx. In summary, we identified an amino acid in domain III that is important for the cytotoxic activity of Etx, thereby providing information on the structure-function relationship of Etx.

Pneumococcal wall teichoic acid is required for the pathogenesis of Streptococcus pneumoniae in murine models: Hongmei Xu , Libin Wang , Jian Huang , Yanqing Zhang , Feng Ma , Jianmin Wang , Wenchun Xu , Xuemei Zhang , Yibing Yin , Kaifeng Wu; J. Microbiol. 2015;53(2):147-154. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4616-4

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Abstract: Pneumococcal asymptomatic colonization of the respiratory tracts is a major risk for invasive pneumococcal disease. We have previously shown that pneumococcal wall teichoic acid (WTA) was involved in pneumococcal infection of sepsis and adherence to epithelial and endothelial cells. In this study, we investigated the contribution of pneumococcal WTA to bacterial colonization and dissemination in murine models. The result showed that nasopharynx colonizing D39 bacterial cells have a distinct phenotype showing an increased exposure of teichoic acids relative to medium-grown bacteria. The WTA-deficient mutants were impaired in their colonization to the nasopharynx and lungs, and led to a mild inflammation in the lungs at 36 h post-inoculation. Pretreatment of the murine nares with WTA reduced the ability of wild type D39 bacteria to colonize the nasopharynx. In addition, the WTA-deficient strain was impaired in its ability to invade the blood and brain following intranasal administration. WTA-deficient D39 strain was reduced in C3 deposition but was more susceptible to the killing by the neutrophils as compared with its parent strain. Our results also demonstrated that the WTA enhanced pneumococcal colonization and dissemination independently of the host strains. These results indicate that WTA plays an important role in pneumococcal pathogenesis, both in colonization and dissemination processes.

Genipin as a novel chemical activator of EBV lytic cycle: Myoungki Son , Minjung Lee , Eunhyun Ryu , Aree Moon , Choon-Sik Jeong , Yong Woo Jung , Gyu Hwan Park , Gi-Ho Sung , Hyosun Cho , Hyojeung Kang; J. Microbiol. 2015;53(2):155-165. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4672-9

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30 Citations

Abstract: Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that causes acute infection and establishes life-long latency. EBV causes several human cancers, including Burkitt's lymphoma, nasopharyngeal and gastric carcinoma. Antiviral agents can be categorized as virucides, antiviral chemotherapeutic agents, and immunomodulators. Most antiviral agents affect actively replicating viruses, but not their latent forms. Novel antiviral agents must be active on both the replicating and the latent forms of the virus. Gardenia jasminoides is an evergreen flowering plant belonging to the Rubiaceae family and is most commonly found growing wild in Vietnam, Southern China, Taiwan, Japan, Myanmar, and India. Genipin is an aglycone derived from an iridoid glycoside called geniposide, which is present in large quantities in the fruit of G. jasminoides. In this study, genipin was evaluated for its role as an antitumor and antiviral agent that produces inhibitory effects against EBV and EBV associated gastric carcinoma (EBVaGC). In SNU719 cells, one of EBVaGCs, genipin caused significant cytotoxicity (70 μM), induced methylation on EBV C promoter and tumor suppressor gene BCL7A, arrested cell-cycle progress (S phases), upregulated EBV latent/lytic genes in a dose-dependent manner, stimulated EBV progeny production, activated EBV F promoter for EBV lytic activation, and suppressed EBV infection. These
results
indicated that genipin could be a promising candidate for antiviral and antitumor agents against EBV and EBVaGC.

Immunological charaterization of monoclonal antibodies used in rapid influenza diagnostic test for detection of the 2009 pandemic influenza A(H1N1)pdm09 infection: Hwajung Yi , Mi-Seon Lee , Joo-Yeon Lee , Hae Kyung Lee , Chun Kang; J. Microbiol. 2015;53(2):166-175. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-4642-2

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Abstract: Since the 2009 pandemic, monoclonal antibodies (mAbs) for rapid influenza diagnostic tests (RIDT) have been developed for specific diagnostics of pandemic viral infection. Most of the mAbs were poorly characterized because of urgency during the pandemic. Further characterization of the mAbs for RIDTs would be beneficial for understanding the immunological properties of the pandemic virus and utilizing the mAbs for other research purposes. In this study, it was confirmed that two mAbs (I38 and D383) in an RIDT for H1N1pdm09 diagnostics were able to detect H1N1pdm09 virus through enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assay (IFA). Also, the two mAbs exhibited reactivity to hemagglutinins (HAs) of both the H1N1pdm09 and 1918 H1N1 viruses; therefore, the RIDT using the mAbs could detect HAs of H1N1pdm09 and also HAs of 1918 H1N1-like strains. In an extension to our previous study, the epitopes (Sa antigenic site and the interface area of F?and vestigial esterase subdomains on the HA1 domain of HA of H1N1pdm09) recognized by the mAbs were corroborated in depth by IFA with escape-mutants from the mAbs and mapping of the epitopes on the crystal structure of human H1N1 viral HAs. Collectively, these results imply that the mAbs for the RIDT may be suitable for use in studying the immunological properties of H1N1pdm09 viruses and that the Sa antigenic site and the interface area between F?and vestigial esterase subdomains on influenza viral HA recognized by the mAbs are immunologically conserved regions between H1N1pdm09 and 1918 H1N1.

Note] Inhibition of quorum sensing in Pseudomonas aeruginosa by two herbal essential oils from Apiaceae family: Ehsan Sepahi , Saeed Tarighi , Farajollah Shahriari Ahmadi , Abdolreza Bagheri; J. Microbiol. 2015;53(2):176-180. Published online January 5, 2015; DOI: https://doi.org/10.1007/s12275-015-4203-8

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Abstract: Ferula (Ferula asafoetida L.) and Dorema (Dorema aucheri Bioss.) both from Apiaceae family were tested for their antiquorum sensing (QS) activity against Pseudomonas aeruginosa. Both essential oils exhibited anti-QS activity at 25 μg/ml of concenteration. At this concenteration Ferula fully abolished and Dorema reduced the violacein production by C. violaceum. Pyocyanin, pyoverdine, elastase and biofilm production were decreased in Ferula oil treatments. Dorema oil reduced pyoverdine and elastase production, while pyocyanin and biofilm production were not affacted. Expresion analysis of QS-dependent genes confirmed our phenotypic data. Our data introduced native Dorema and Ferula plants as novel QS and virulence inhibitors.

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