TY - JOUR A1 - Tonon, C. A1 - Breitenbach, Romy A1 - Voigt, Oliver A1 - Turci, F. A1 - Gorbushina, Anna A1 - Favero-Longo, S. E. T1 - Hyphal morphology and substrate porosity -rather than melanization- drive penetration of black fungi into carbonate substrates N2 - Due to their ability to penetrate, deteriorate and discolour stone surfaces, rock-inhabiting black fungi represent a remarkable issue for cultural heritage conservation. Black microcolonial fungi (MCF) can also adapt to different environmental conditions, by converting from yeast-like morphology to a peculiar meristematic development with swollen cells (torulose hyphae, TH), to extremely thin structures (filamentous hyphae, FH). Furthermore, black MCF produce protective pigments: melanin, dark pigment particularly evident on light stone surfaces, and carotenoids. Black fungi produce melanin in critical, oligotrophic conditions as well as constitutively. Melanin function is mostly related to stress resistance and the ability of fungi to generate appressorial turgor to actively penetrate plant cells in pathogenic species. An involvement of melanins in stone surface penetration has been suggested, but not experimentally proved. In this work, we tested the role of hyphal melanisation in penetration mechanisms on the model black fungus Knufia petricola A95 in lab conditions. The wild-type and three mutants with introduced targeted mutations of polyketide-synthases (melanin production) and/or phytoene dehydrogenase (carotenoid synthesis) were inoculated on artificial carbonate pellets (pressed Carrara marble powder) of different porosity. After 5, 10, 17 and 27 weeks, hyphal penetration depth and spread were quantified on periodic acid Schiff-stained cross-sections of the pellets, collecting measurements separately for TH and FH. Droplet assay of the mutants on different media were conducted to determine the role of nutrients in the development of different fungal morphologies. In our in vitro study, the hyphal penetration depth, never exceeding 200 μm, was proven to be consistent with observed penetration patterns on stone heritage carbonate substrates. Pellet porosity affected penetration patterns of TH, which developed in voids of the more porous pellets, instead than actively opening new passageways. Oppositely, the thin diameter of FH allowed their penetration independently of substrate porosity. Instead, the long-hypothesized crucial role of melanin in black MCF hyphal penetration should be rejected. TH were developed within the pellets also by melanin deficient strains, and melanized strains showed an endolithic component of non-melanized TH. FH were non-melanized for all the strains, but deeply penetrated all pellet types, with higher penetration depth probably related to their potential exploratory (nutrient-seeking) role, while TH may be more related to a resistance to surface stress factors. In the melanin deficient strains, the absence of melanin caused an increased penetration rate of FH, hypothetically related to an earlier necessity to search for organic nutrients. KW - Biodeterioration KW - Bioreceptivity KW - Black microcolonial fungi KW - Marble KW - Stone cultural heritage KW - Stress tolerance PY - 2020 U6 - https://doi.org/10.1016/j.culher.2020.11.003 VL - 48 SP - 244 EP - 253 PB - Elsevier Masson SAS CY - Paris, Amsterdam AN - OPUS4-51933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, Julia T1 - Looking through the eyes of fungi: from photoperception to photoresponses and beyond N2 - Sunlight is an almost unavoidable environmental cue and plays a fundamental role in the biology of pro- and eukaryotic organisms. To cope with sunlight-associated stresses e.g., high temperatures, UV radiation, accumulation of reactive oxygen species, desiccation, and osmotic stress, it is important for organisms to accurately sense and respond to changes in light. The benefits of light are obvious for green organisms such as cyanobacteria, algae and plants which use light as an energy source (photosynthesis). Fungi that can share light-flooded habitats with phototrophs may profit from their excess photosynthetic products. Examples are the plant pathogen Botrytis cinerea, the gray mold fungus, and the rock inhabitant Knufia petricola, a microcolonial black fungus which forms multispecies biofilms with bacteria and algae. T2 - 20th Symposium of the Research Training Group on Bioactive Peptides – The colorful tree of life CY - Berlin, Germany DA - 23.01.2024 KW - Black fungi KW - Melanin KW - Stress tolerance PY - 2024 AN - OPUS4-59543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - C., Ruibal A1 - L., Selbmann A1 - Serap, Avci A1 - Martin-Sanchez, Pedro Maria A1 - Gorbushina, Anna ED - Gorbushina, Anna T1 - Roof-Inhabiting Cousins of Rock-Inhabiting Fungi: Novel Melanized Microcolonial Fungal Species from Photocatalytically Reactive Subaerial Surfaces N2 - Subaerial biofilms (SAB) are an important factor in weathering, biofouling, and biodeterioration of bare rocks, building materials, and solar panel surfaces. The realm of SAB is continually widened by modern materials, and the settlers on these exposed solid surfaces always include melanized, stress-tolerant microcolonial ascomycetes. After their first discovery on desert rock surfaces, these melanized chaetothyrialean and dothidealean ascomycetes have been found on Mediterranean monuments after biocidal treatments, Antarctic rocks and solar panels. New man-made modifications of surfaces (e.g., treatment with biocides or photocatalytically active layers) accommodate the exceptional stress-tolerance of microcolonial fungi and thus further select for this well-protected ecological group. Melanized fungal strains were isolated from a microbial community that developed on highly photocatalytic roof tiles after a long-term environmental exposure in a maritime-influenced region in northwestern Germany. Four of the isolated strains are described here as a novel species, Constantinomyces oldenburgensis, based on multilocus ITS, LSU, RPB2 gene phylogeny. Their closest relative is a still-unnamed rock-inhabiting strain TRN431, here described as C. patonensis. Both species cluster in Capnodiales, among typical melanized microcolonial rock fungi from different stress habitats, including Antarctica. These novel strains flourish in hostile conditions of highly oxidizing material surfaces, and shall be used in reference procedures in material testing. KW - Microcolonial fungi KW - Multilocus phylogeny KW - Photocatalytic surfaces KW - Subaerial biofilms KW - Stress tolerance KW - Constantinomyces PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-455182 VL - 8 IS - 3 SP - 30 EP - 44 PB - MDPI CY - Basel, Schweiz AN - OPUS4-45518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -