TY - CONF A1 - Knabe, Nicole A1 - Breitenbach, Romy T1 - Microscopy-based Raman spectroscopy of fungal melanins in a genetically amenable ascomycete N2 - Fungal melanins are distinctive markers of rock-inhabiting ascomycetes. These complex polyphenols play important roles in stress tolerance while being essential components of fungal cell walls and useful biomarkers. Here we report signatures of melanins and carotenoids in pigment mutant strains of the black yeast Knufia petricola A95 using Raman spectroscopy T2 - 11th Workshop of FT-IR Spectroscopy in Microbiological and Medical Diagnostics CY - Berlin, Germany DA - 19.10.2017 KW - Raman KW - Melanin KW - Rock-inhabiting fungus PY - 2017 AN - OPUS4-43124 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knabe, Nicole T1 - Some like it on the rocks: ascomycetes with manifold protective pigments N2 - Black ascomycetous microcolonial fungi (MCF) are persistent inhabitants of rock surfaces in deserts as well as ubiquitous in other wide-spread terrestrial ecosystems including man-made materials such as solar panels. The ability of MCF to cope with multiple, rapidly fluctuating stresses makes the group an interesting subject in the study of stress resistance. Carotenoids and melanin are amongst the protective pigments that contribute to the robustness of MCF. We studied their role in stress resistance of the non-pathogenic rock-inhabiting fungus Knufia petricola (Chaetothyriales) strain A95. Disruption of melanin synthesis affects not only oxidative-stress resistance but also the extracellular polysaccharide (EPS) matrix and lipid composition of the cell membrane. T2 - 29th Fungal Genetics Conference CY - Pacific Grove, USA DA - 14.03.2017 KW - Knufia KW - Melanin KW - Carotenoids KW - EPS PY - 2017 AN - OPUS4-39673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knabe, Nicole T1 - Some like it on the rocks: recurring stresses select for rock-inhabiting fungi with manifold protective pigments N2 - Black ascomycetous microcolonial fungi (MCF) are persistent inhabitants of rock surfaces in deserts as well as ubiquitous in other wide-spread terrestrial ecosystems including man-made materials such as solar panels. The ability of MCF to cope with multiple, rapidly fluctuating stresses makes the group an interesting subject in the study of stress resistance. Carotenoids and melanin are amongst the protective pigments that contribute to the robustness of MCF. We studied their role in stress resistance of the non-pathogenic rock-inhabiting fungus Knufia petricola (Chaetothyriales) strain A95. Disruption of melanin synthesis affects not only oxidative-stress resistance but also the extracellular polysaccharide (EPS) matrix and lipid composition of the cell membrane. T2 - 29th Fungal Genetics Conference CY - Pacific Grove, USA DA - 14.03.2017 KW - Black yeast KW - Cell wall KW - Pigment KW - Melanin PY - 2017 AN - OPUS4-39671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knabe, Nicole T1 - Roles of protective pigments in oxidative stress responses of the rock-inhabiting model fungus Knufia petricola A95 T2 - 28th Fungal Genetics Conference CY - Pacific Grove, California, USA DA - 2015-03-17 PY - 2015 AN - OPUS4-33057 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knabe, Nicole A1 - Gorbushina, Anna T1 - Life on the rocks or deserts at your doorstep T2 - Seminar Berlin Center for Genomics in Biodiversity Research CY - Berlin, Germany DA - 2015-04-15 PY - 2015 AN - OPUS4-33101 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gerrits, Ruben A1 - Wirth, R. A1 - Schreiber, A. A1 - Feldmann, Ines A1 - Knabe, Nicole A1 - Schott, J, A1 - Benning, L.G. A1 - Gorbushina, Anna T1 - High-resolution imaging of fungal biofilm-induced olivine weathering N2 - Many microorganisms including free-living and symbiotic fungi weather minerals through the formation of biofilms on their surface. Weathering thus proceeds not only according to the mineral’s chemistry and the environmental conditions but also according to the local biofilm chemistry. These processes can be dissected in experiments with defined environmental settings and by employing genetic tools to modify traits of the fungal biofilm. Biofilms of the rock-inhabiting fungus Knufia petricola strain A95 (wild-type, WT) and its melanin-deficient mutant (ΔKppks) were grown on polished olivine sections in subaerial (air-exposed) and subaquatic (submerged) conditions. After seven months of interaction at pH 6 and 25°C, the fungus-mineral interface and abiotic olivine surface were compared using high resolution transmission electron microscopy (HRTEM). The abiotic, subaquatic olivine section showed a 25 nm thick, continuous amorphous layer, enriched in Fe and depleted in Si compared to the underlying crystalline olivine. This amorphous layer formed either through a coupled interfacial dissolution reprecipitation mechanism or through the adsorption of silicic acid on precipitated ferric hydroxides. Its thickness was likely enhanced by mechanical stresses of polishing. Directly underneath a fungal biofilm (WT and mutant alike), the surface remained mostly crystalline and was strongly etched and weathered, indicating enhanced olivine dissolution. The correlation between enhanced olivine dissolution and the absence of a continuous amorphous layer is a strong indication of the dissolution-inhibiting qualities of the latter. We propose that the fungal biofilm sequesters significant amounts of Fe, preventing formation of the amorphous layer and driving olivine dissolution onwards. The seemingly similar olivine surface underneath both WT and mutant biofilms illustrates the comparably insignificant role of specific biofilm traits in the weathering of olivine once biofilm attachment is imposed. Under subaerial conditions, the absence of water on the abiotic surface prohibited olivine dissolution. This was overcome by the water retention capacities of both the WT and mutant biofilm: the olivine surface underneath subaerial fungal biofilms was as weathered as the corresponding subaquatic olivine surface. Under the studied environmental settings, the effect of fungal biofilms on olivine weathering seems to be universal, independent of the production of melanin, the composition of extracellular polymeric substances (EPS) or air-exposure. KW - Bio-weathering KW - Forsterite KW - Extracellular polymeric substances KW - Melanin KW - Black fungi PY - 2021 DO - https://doi.org/10.1016/j.chemgeo.2020.119902 VL - 559 SP - 119902 PB - Elsevier B.V. AN - OPUS4-51403 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knabe, Nicole T1 - Genetics for geomycology N2 - Black microcolonial fungi (MCF) are persistent inhabitants of rock surfaces. Biofilm establishment and more importantly, quantification of its geological input are so far only possible to be studied in simplified, well-controlled laboratory experiments. Therefore, the ability of MCF to cope with multiple, rapidly fluctuating stresses makes the group an interesting subject in the study of stress resistance but also in mineral weathering processes. We studied the role of protective pigments in stress resistance and mineral weathering of the rock-inhabiting fungus Knufia petricola (Chaetothyriales) strain A95. T2 - 12th conference of the VAAM special group "Molecular Biology of Fungi" CY - Jena, Germany DA - 28.09.2017 KW - Mineral weathering KW - Rock-inhabiting fungis PY - 2017 AN - OPUS4-43123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dittrich, Maria A1 - Paulo, Carlos A1 - Knabe, Nicole A1 - Sturm, Heinz A1 - Zaitsev, Vladimir A1 - Gorbushina, Anna T1 - Microscopic Raman study of fungal pigment using the genetically amenable rock inhabitant Knufia petricola as a model organism N2 - Fungal pigments such as melanin and carotenoids are distinctive markers of animal and plant pathogenic fungi as well as their environmental relatives. These complex pigments play important roles in pathogenicity and stress tolerance while also being useful as biomarkers. Accordingly, it is important to be able to identify in situ the pigments in black fungi, a group of clinical and environmental importance. In this study, wild-type and genetically modified strains of Knufia petricola A95 and wild fungal cells attached to ancient rock were investigated for their spectroscopic and microscopic Raman features and morphological appearance. Knockout mutants of melanin synthesis genes pks1 (polyketide synthase), sdh1 (scytalone dehydratase), and both pks1 and the carotenoid synthesis gene phd1 (phytoene desaturase) were studied We applied two different Raman microscopes using two lasers, with 633 nm and 488 nm wavelengths. We analyzed and compared Raman spectra between the measured reference substances and the mutant and wild-type strains. In the wild strain WT:A95, the peaks close to melanin peals were found at 1353 cm−1 and 1611 cm−1. There are no characteristic melanin peaks at 1580–1600 cm−1 and around 1350 cm−1 at the spectrum of the Δpks1/Δphd1 mutant and the Δsdh1 mutant. The Δpks1 mutant spectrum has the peaks at the beta-carotene v2 C-C in-plane stretch at 1155 cm−1 and v3 C-CH3 deformation at 1005 cm−1. The peaks of carotenoids and melanin were found in all mutants and the wild strain, except the Δpks1/Δphd1 mutant. Raman spectra allow for discrimination between the various pigments. Hence, interactions between natural fungal melanin, as well as other protective pigments, and complex environmental matrices can be characterized on a range of spatial and temporal scales. KW - Raman Spectroscopy KW - Instrumentation KW - Analytical Chemistry KW - Knufia petricola KW - Confocal microscopy KW - Atomic and Molecular Physics and Optics PY - 2023 DO - https://doi.org/10.1016/j.saa.2023.123250 SN - 1386-1425 VL - 303 SP - 1 EP - 11 PB - Elsevier BV AN - OPUS4-58792 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knabe, Nicole T1 - Why some like it on the rocks: Recurring stresses select for organisms with manifold protective pigments T2 - 11th Molecular Biology of Fungi Conference CY - Berlin; Germany DA - 2015-10-07 PY - 2015 AN - OPUS4-34570 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Knabe, Nicole A1 - Gorbushina, Anna ED - Gurtler, V. ED - Trevors, J. T. T1 - Territories of rock-inhabiting fungi: Survival on and alteration of solid air-exposed surfaces N2 - Subaerial biofilms that are omnipresent at the interface between all solid substrates and the atmosphere are composed of a unique and widespread group of ascomycetes called rock-inhabiting fungi or microcolonial fungi (MCF), typically in communities with other microorganisms. While subaerial biofilms in toto have important roles in mineral weathering and biodeterioration of materials, methodological approaches to subaerial biofilm communities are diverse and frequently focussed on MCF. Here, we review the historical development of the research methods applied in the field and consider perspectives to increase our understanding of the biofilm-induced changes of solid substrate surfaces. KW - Biologically induced mineral weathering KW - Geobiology KW - Microcolonial fungi KW - Subaerial biofilm KW - Symbiosis PY - 2018 UR - https://linkinghub.elsevier.com/retrieve/pii/S0580951718300047 SN - 9780128146040 DO - https://doi.org/10.1016/bs.mim.2018.06.001 VL - 45 SP - Chapter 6, 145 EP - 169 PB - Elsevier AN - OPUS4-47181 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knabe, Nicole T1 - Differential gene expression and oxidative stress tolerance in the rock-inhabiting fungus Knufia petricola A95 N2 - Microcolonial fungi (MCF) are able to survive extreme environmental conditions. This study is focusing on responses to oxidative stress - using the rock fungus Knufia petricola strain A95. Comparative gene expression analyses of a wild type and a PKS mutant are used to identify genes which are especially regulated under oxidative stress conditions to help elucidate mechanisms of cell wall maturation and oxidative stress defence strategies. T2 - VAAM-Jahrestagung 2016 CY - Jena, Germany DA - 13.03.2016 KW - MCF KW - RNA-Seq KW - Oxidative stress PY - 2016 AN - OPUS4-37966 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -