TY - JOUR A1 - Catanzaro, Ilaria A1 - Gorbushina, Anna A1 - Onofri, Silvano A1 - Schumacher, Julia T1 - 1,8‐Dihydroxynaphthalene (DHN) melanin provides unequal protection to black fungi Knufia petricola and Cryomyces antarcticus from UV‐B radiation N2 - Black fungi on rock surfaces endure a spectrum of abiotic stresses, including UV radiation. Their ability to tolerate extreme conditions is attributed to the convergent evolution of adaptive traits, primarily highly melanized cell walls. However, studies on fungal melanins have not provided univocal results on their photoprotective functions. Here, we investigated whether the black fungi Knufia petricola and Cryomyces antarcticus only use DHN melanin or may employ alternative mechanisms to counteract UV‐induced damage. For this, melanized wild types and non‐melanized Δpks1 mutants were exposed to different doses of UV‐B (312 nm) followed by incubation in constant darkness or in light–dark cycles to allow light‐dependent DNA repair by photolyases (photoreactivation). C. antarcticus could tolerate higher UV‐B doses but was sensitive to white light, whereas K. petricola showed the opposite trend. DHN melanin provided UV‐B protection in C. antarcticus, whereas the same pigment or even carotenoids proved ineffective in K. petricola. Both fungi demonstrated functional photoreactivation in agreement with the presence of photolyase‐encoding genes. Our findings reveal that although the adaptive trait of DHN melanization commonly occurs across black fungi, it is not equally functional and that there are species‐specific adaptations towards either UV‐induced lesion avoidance or repair strategies. KW - Rock-inhabiting Ascomycetes KW - Pigment KW - Photoprotection KW - Photolyase KW - Disinfection PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-616859 DO - https://doi.org/10.1111/1758-2229.70043 VL - 16 IS - 6 SP - 1 EP - 13 PB - Wiley AN - OPUS4-61685 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scales, B. S. A1 - Hasenrück, C. A1 - Moldaenke, L. A1 - Hassa, J. A1 - Rückert-Reed, C. A1 - Rummel, C. A1 - Völkner, C. A1 - Rynek, R. A1 - Busche, T. A1 - Kalinowski, J. A1 - Jahnke, A. A1 - Schmitt-Jansen, M. A1 - Wendt-Potthoff, K. A1 - Oberbeckmann, Sonja T1 - Hunting for pigments in bacterial settlers of the Great Pacific Garbage Patch N2 - The Great Pacific Garbage Patch, a significant collection of plastic introduced by human activities, provides an ideal environment to study bacterial lifestyles on plastic substrates. We proposed that bacteria colonizing the floating plastic debris would develop strategies to deal with the ultravioletexposed substrate, such as the production of antioxidant pigments. We observed a variety of pigmentation in 67 strains that were directly cultivated from plastic pieces sampled from the Garbage Patch. The genomic analysis of four representative strains, each distinct in taxonomy, revealed multiple pathways for carotenoid production. These pathways include those that produce less common carotenoids and a cluster of photosynthetic genes. This cluster appears to originate from a potentially new species of the Rhodobacteraceae family. This represents the first report of an aerobic anoxygenic photoheterotrophic bacterium from plastic biofilms. Spectral analysis showed that the bacteria actively produce carotenoids, such as betacarotene and beta-cryptoxanthin, and bacteriochlorophyll a. Furthermore, we discovered that the genetic ability to synthesize carotenoids is more common in plastic biofilms than in the surrounding water communities. Our findings suggest that plastic biofilms could be an overlooked source of bacteria-produced carotenoids, including rare forms. It also suggests that photoreactive molecules might play a crucial role in bacterial biofilm communities in surface water. KW - Microplastics KW - Biofilm KW - Pigment KW - Microorganisms PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605725 DO - https://doi.org/10.1111/1462-2920.16639 SN - 1462-2912 VL - 26 IS - 6 SP - e16639 PB - John Wiley & Sons Ltd. AN - OPUS4-60572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, Julia T1 - Versatile DHN melanin – spotlight on its function in microcolonial black fungi N2 - Dihydroxynaphthalene (DHN) melanin is produced by diverse Ascomycetes via slightly differing biosynthetic routes. The polyketide synthases (PKS) release the heptaketide YWA1, the hexaketide AT4HN or the pentaketide T4HN. The first two products are deacetylated by ‘yellowish-green’ hydrolases to T4HN, and T4HN is further converted by a core set of enzymes to DHN. Final polymerization steps are accomplished by multicopper oxidases. DHN melanogenesis is often regulated in a spatial and temporal fashion resulting e.g., in melanized reproduction and survival structures of the foliar plant pathogen Botrytis cinerea (Schumacher 2016, Mol Microbiol). In contrast, a polyphyletic group of Ascomycetes (microcolonial fungi/ black yeasts) dwelling in hostile habitats such as bare rock surfaces in hot and cold deserts, exhibits constitutive melanogenesis. Here, DHN melanin builds a protective layer around all vegetative cells thus contributing to the survival of diverse environmental stresses even without specialized reproduction structures. For studying the relevance of constitutive DHN melanogenesis for tolerance of abiotic and biotic stresses, adhesion to substrates and subsequent damage of colonized surfaces, the rock-inhabiting fungus Knufia petricola was chosen as gene functions in this fungus can be studied by CRISPR/Cas9-based genome editing. The putative melanogenic genes were identified in the genome of K. petricola, deleted to confirm their involvement in DHN melanogenesis and co-expressed in Saccharomyces cerevisiae for reconstruction of the synthesis pathway. Phenotypes of DHN-deficient mutants are studied. Here, we will discuss the role of the DHN melanin layer on the outer cell wall in tolerating UV irradiation. T2 - Annual conference 2023 of the Association for General and Applied Microbiology CY - Göttingen, Germany DA - 10.09.2023 KW - Pigment KW - UV radiation KW - Tolerance PY - 2023 AN - OPUS4-58425 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, Julia T1 - DHN melanin – synthesis, regulation, and functions in Knufia petricola N2 - Dihydroxynaphthalene (DHN) melanin is produced by diverse Ascomycetes via slightly differing biosynthetic routes. The polyketide synthases (PKS) release the heptaketide YWA1, the hexaketide AT4HN or the pentaketide T4HN. The first two products are deacetylated by ‘yellowish-green’ hydrolases to T4HN, and T4HN is further converted by a core set of enzymes to DHN. Final polymerization steps are accomplished by multicopper oxidases. DHN melanogenesis is often regulated in a spatial and temporal fashion resulting e.g., in melanized reproduction and survival structures of the foliar plant pathogen Botrytis cinerea (Schumacher 2016, Mol Microbiol). In contrast, microcolonial black fungi exhibit constitutive melanogenesis. Here, DHN melanin builds a protective layer around all vegetative cells thus contributing to the survival of diverse environmental stresses even without specialized reproduction structures. For studying the regulation and relevance of DHN melanogenesis for tolerance of abiotic and biotic stresses, adhesion to substrates and subsequent damage of colonized surfaces, the rock-inhabiting fungus Knufia petricola was chosen as gene functions in this fungus can be studied by CRISPR/Cas9-based genome editing. The putative melanogenic genes were identified in the genome of K. petricola, deleted to confirm their involvement in DHN melanogenesis and co-expressed in Saccharomyces cerevisiae for reconstruction of the synthesis pathway. Phenotypes of deletion mutants are studied for specifying the functions of DHN melanin in K. petricola. T2 - IUBMB Focused Meeting on Extremophilic Fungi (FUN-EX) CY - Ljubliana, Slovenia DA - 19.09.2023 KW - Pigment KW - Fungus KW - Heterologous expression PY - 2023 AN - OPUS4-58430 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -