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Utrecht, Netherlands

Stief P.,Max Planck Institute for Marine Microbiology | Stief P.,University of Southern Denmark | Fuchs-Ocklenburg S.,Max Planck Institute for Marine Microbiology | Fuchs-Ocklenburg S.,University of Kaiserslautern | And 8 more authors.
BMC Microbiology | Year: 2014

Background: A wealth of microbial eukaryotes is adapted to life in oxygen-deficient marine environments. Evidence is accumulating that some of these eukaryotes survive anoxia by employing dissimilatory nitrate reduction, a strategy that otherwise is widespread in prokaryotes. Here, we report on the anaerobic nitrate metabolism of the fungus Aspergillus terreus (isolate An-4) that was obtained from sediment in the seasonal oxygen minimum zone in the Arabian Sea, a globally important site of oceanic nitrogen loss and nitrous oxide emission. Results: Axenic incubations of An-4 in the presence and absence of oxygen and nitrate revealed that this fungal isolate is capable of dissimilatory nitrate reduction to ammonium under anoxic conditions. A 15N-labeling experiment proved that An-4 produced and excreted ammonium through nitrate reduction at a rate of up to 175 nmol 15NH4 + g-1 protein h-1. The products of dissimilatory nitrate reduction were ammonium (83%), nitrous oxide (15.5%), and nitrite (1.5%), while dinitrogen production was not observed. The process led to substantial cellular ATP production and biomass growth and also occurred when ammonium was added to suppress nitrate assimilation, stressing the dissimilatory nature of nitrate reduction. Interestingly, An-4 used intracellular nitrate stores (up to 6-8 μmol NO3 - g-1 protein) for dissimilatory nitrate reduction. Conclusions: Our findings expand the short list of microbial eukaryotes that store nitrate intracellularly and carry out dissimilatory nitrate reduction when oxygen is absent. In the currently spreading oxygen-deficient zones in the ocean, an as yet unexplored diversity of fungi may recycle nitrate to ammonium and nitrite, the substrates of the major nitrogen loss process anaerobic ammonium oxidation, and the potent greenhouse gas nitrous oxide. © 2014 Stief et al.; licensee BioMed Central Ltd.

De Baere T.,Ghent University | De Baere T.,Scientific Institute of Public Health | Summerbell R.,Fungal Diversity Center | Summerbell R.,Sporometrics Inc. | And 4 more authors.
Journal of Medical Microbiology | Year: 2010

A total of 95 isolates, belonging to 33 species of five dermatophyte genera, i.e. Arthroderma (15 species), Chrysosporium (two), Epidermophyton (one), Microsporum (three) and Trichophyton (12), were studied using internal transcribed spacer 2 (ITS2)-PCR-RFLP analysis (ITS2-RFLP), consisting of amplification of the ITS2 region, restriction digestion with BstUI (CG/CG) and restriction fragment length determination by capillary electrophoresis. ITS2-RFLP analysis proved to be most useful for identification of species of the genera Arthroderma, Chrysosporium and Epidermophyton, but could not distinguish between several Trichophyton species. The identification results are in agreement with established and recent taxonomical insights into the dermatophytes; for example, highly related species also had closely related and sometimes difficult-to-discriminate ITS2-RFLP patterns. In some cases, several ITS2-RFLP groups could be distinguished within species, again mostly in agreement with the taxonomic delineations of subspecies and/or genomovars, confirming the relevance of ITS2-RFLP analysis as an identification technique and as a useful taxonomic approach. © 2010 SGM.

Senkardesler A.,Ege University | Buyck B.,French Natural History Museum | Hofstetter V.,Station de Rechercheagroscope Changins Wadenswil | Verberen A.,Ghent University | And 24 more authors.
Mycotaxon | Year: 2010

Formal proposals to conserve or protect fungal names as well as proposals to amend the INTERNATIONAL CODE OF NOMENCLATURE of immediate interest to mycologists are now published concurrently in MYCOTAXON and TAXON. Conservation proposals include Prop. 1918 (to conserve the name Dermatocarpon bucekii against Placidium steineri), Prop. 1919 (to conserve the name Lactarius with a conserved type), Prop. 1926 (to conserve the name Cladia against Heterodea, and Prop. 1927 (to conserve the name Agaricus rachodes with that spelling). Props. 117-119 to amend the CODE ask for pre-publication deposit of nomenclatural information in a recognized repository for valid publication of fungal names.

van Veluw G.J.,University Utrecht | Teertstra W.R.,University Utrecht | de Bekker C.,University Utrecht | Vinck A.,University Utrecht | And 7 more authors.
Studies in Mycology | Year: 2013

Black pigmented conidia of Aspergillus niger give rise to micro-colonies when incubated in liquid shaken medium. These micro-colonies are heterogeneous with respect to gene expression and size. We here studied the biophysical properties of the conidia of a control strain and of strains in which the fwnA, olvA or brnA gene is inactivated. These strains form fawn-, olive-, and brown-coloured conidia, respectively. The δolvA strain produced larger conidia (3.8 μm) when compared to the other strains (3.2-3.3 μm). Moreover, the conidia of the δolvA strain were highly hydrophilic, whereas those of the other strains were hydrophobic. The zeta potential of the δolvA conidia in medium was also more negative when compared to the control strain. This was accompanied by the near absence of a rodlet layer of hydrophobins. Using the Complex Object Parametric Analyzer and Sorter it was shown that the ratio of individual hyphae and micro-colonies in liquid shaken cultures of the deletion strains was lower when compared to the control strain. The average size of the micro-colonies of the control strain was also smaller (628 μm) than that of the deletion strains (790-858 μm). The size distribution of the micro-colonies of the δfwnA strain was normally distributed, while that of the other strains could be explained by assuming a population of small and a population of large micro-colonies. In the last set of experiments it was shown that relative expression levels of gpdA, and AmyR and XlnR regulated genes correlate in individual hyphae at the periphery of micro-colonies. This indicates the existence of transcriptionally and translationally highly active and lowly active hyphae as was previously shown in macro-colonies. However, the existence of distinct populations of hyphae with high and low transcriptional and translational activity seems to be less robust when compared to macro-colonies grown on solid medium. © CBS-KNAW Fungal Biodiversity Centre, P.O. Box 85167, 3508 AD Utrecht, The Netherlands.

de Jong M.A.W.P.,University of Amsterdam | de Jong M.A.W.P.,VU University Amsterdam | Vriend L.E.M.,VU University Amsterdam | Theelen B.,Fungal Diversity Center | And 4 more authors.
Molecular Immunology | Year: 2010

Langerhans cells (LCs) lining the stratified epithelia and mucosal tissues are the first antigen presenting cells to encounter invading pathogens, such as viruses, bacteria and fungi. Fungal infections form a health threat especially in immuno-compromised individuals. LCs express C-type lectin Langerin that has specificity for mannose, fucose and GlcNAc structures. Little is known about the role of human Langerin in fungal infections. Our data show that Langerin interacts with both mannan and β-glucan structures, common cell-wall carbohydrate structures of fungi. We have screened a large panel of fungi for recognition by human Langerin and, strikingly, we observed strong binding of Langerin to a variety of Candida and Saccharomyces species and Malassezia furfur, but very weak binding was observed to Cryptococcus gattii and Cryptococcus neoformans. Notably, Langerin is the primary fungal receptor on LCs, since the interaction of LCs with the different fungi was blocked by antibodies against Langerin. Langerin recognizes both mannose and β-glucans present on fungal cell walls and our data demonstrate that Langerin is the major fungal pathogen receptor on human LCs that recognizes pathogenic and commensal fungi. Together these data may provide more insight in the role of LCs in fungal infections. © 2009 Elsevier Ltd.

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