Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Povzetek: Many species of black yeasts can survive extremely harsh conditions and can quickly adapt to novel environments. These traits were proposed to have a role in the ability of some fungal species tocolonise indoor habitats inhospitable for majority of microorganisms, and to cause (opportunistic)infections in humans. In order to better understand the stress tolerance of black yeasts and thereby their opportunism, we focused our research on the three model black yeasts: the polyextremotolerant Au-reobasidium melanogenum and Exophiala dermatitidis, and the extremely halotolerant Hortaeawerneckii. These black yeasts are shown to thrive at temperatures, salinities, pH values and, H2O2 concentrations that inhibit growth of mesophilic species. Most importantly, unlike their close relatives they can not only grow, but also synthesize siderophores (E. dermatitidis) or degradeproteins (A. melanogenum) at 37 °C - traits that are crucial for pathogenesis in humans. These results support the hypothesis that the ability to cope with various environmental stresses is linked to the opportunistic behaviour of fungi. Therefore, better understanding of the connections between the stress-tolerant biology of black fungi and their ability to cause disease is needed, in particular due to their changing interactions with humans and their emerging pathogenicity.
Ključne besede: melanised fungi, temperature, NaCl, pH tolerance, ROS, oligotrophism, proteolytic activity, capsule
Objavljeno v DiRROS: 01.08.2024; Ogledov: 106; Prenosov: 63
Celotno besedilo (1,00 MB)
Gradivo ima več datotek! Več...

Povzetek: Fungal spores and mycelium fragments are particles which become and remain airborne and have been subjects of aerobiological studies. The presence and the abundance of taxa in aerobiological samples can be very variable and impaired by changeable climatic conditions. Because many fungi produce mycotoxins and both their mycelium fragments and spores are potential allergens, monitoring the presence of these taxa is of key importance. So far data on exposure and sensitization to fungal allergens are mainly based on the assessment of few, easily identifiable taxa and focused only on certain environments. The microscopic method used to analyze aerobiological samples and the inconspicuous fungal characters do not allow a in depth taxonomical identification. Here, we present a first assessment of fungal diversity from airborne samples using a DNA metabarcoding analysis. The nuclear ITS2 region was selected as barcode to catch fungal diversity in mixed airborne samples gathered during two weeks in four sites of North-Eastern and Central Italy. We assessed the taxonomic composition and diversity within and among the sampled sites and compared the molecular data with those obtained by traditional microscopy. The molecular analyses provide a tenfold more comprehensive determination of the taxa than the traditional morphological inspections. Our results prove that the metabarcoding analysis is a promising approach to increases quality and sensitivity of the aerobiological monitoring. The laboratory and bioinformatic workflow implemented here is now suitable for routine, high-throughput, regional analyses of airborne fungi.
Ključne besede: fungi, fungal spores, taxonomy, sequence databases
Objavljeno v DiRROS: 24.07.2024; Ogledov: 271; Prenosov: 99
Celotno besedilo (2,84 MB)
Gradivo ima več datotek! Več...

Povzetek: Based on seven- and three-gene datasets, we discuss four alternative approaches for a reclassification of Fomitopsidaceae (Polyporales, Basidiomycota). After taking into account morphological diversity in the family, we argue in favour of distinguishing three genera only, viz. Anthoporia, Antrodia and Fomitopsis. Fomitopsis becomes a large genus with 128 accepted species, containing almost all former Fomitopsis spp. and most species formerly placed in Antrodia, Daedalea and Laccocephalum. Genera Buglossoporus, Cartilosoma, Daedalea, Melanoporia, Neolentiporus, alongside twenty others, are treated as synonyms of Fomitopsis. This generic scheme allows for morphologically distinct genera in Fomitopsidaceae, unlike other schemes we considered. We provide arguments for retaining Fomitopsis and suppressing earlier (Daedalea, Caloporus) or simultaneously published generic names (Piptoporus) considered here as its synonyms. Taxonomy of nine species complexes in the genus is revised based on ITS, ITS + TEF1, ITS + TEF1 + RPB1 and ITS + TEF1 + RPB2 datasets. In total, 17 species are described as new to science, 26 older species are reinstated and 26 currently accepted species names are relegated to synonymy. A condensed identification key for all accepted species in the genus is provided.
Ključne besede: brown-rot fungi, new taxa, phylogeny, polypores, taxonomy
Objavljeno v DiRROS: 28.02.2024; Ogledov: 521; Prenosov: 328
Celotno besedilo (12,89 MB)
Gradivo ima več datotek! Več...

Povzetek: Increasingly, national space agencies are expanding their goals to include Mars exploration with sample return. To better protect Earth and its biosphere from potential extraterrestrial sources of contamination, as set forth in the Outer Space Treaty of 1967, international efforts to develop planetary protection measures strive to understand the danger of cross-contamination processes in Mars sample return missions. We aim to better understand the impact of the martian surface on microbial dormancy and survivability. Radiation resistance of microbes is a key parameter in considering survivability of microbes over geologic times on the frigid, arid surface of Mars that is bombarded by solar and galactic cosmic radiation. We tested the influence of desiccation and freezing on the ionizing radiation survival of six model microorganisms: vegetative cells of two bacteria (Deinococcus radiodurans, Escherichia coli) and a strain of budding yeast (Saccharomyces cerevisiae); and vegetative cells and endospores of three Bacillus bacteria (B. subtilis, B. megaterium, B. thuringiensis). Desiccation and freezing greatly increased radiation survival of vegetative polyploid microorganisms when applied separately, and when combined, desiccation and freezing increased radiation survival even more so. Thus, the radiation survival threshold of polyploid D. radiodurans cells can be extended from the already high value of 25 kGy in liquid culture to an astonishing 140 kGy when the cells are both desiccated and frozen. However, such synergistic radioprotective effects of desiccation and freezing were not observed in monogenomic or digenomic Bacillus cells and endospores, which are generally sterilized by 12 kGy. This difference is associated with a critical requirement for survivability under radiation, that is, repair of genome damage caused by radiation. Deinococcus radiodurans and S. cerevisiae accumulate similarly high levels of the Mn antioxidants that are required for extreme radiation resistance, as do endospores, though they greatly exceed spores in radioresistance because they contain multiple identical genome copies, which in D. radiodurans are joined by persistent Holliday junctions. We estimate ionizing radiation survival limits of polyploid DNA-based life-forms to be hundreds of millions of years of background radiation while buried in the martian subsurface. Our findings imply that forward contamination of Mars will essentially be permanent, and backward contamination is a possibility if life ever existed on Mars.
Ključne besede: ionizing radiation, life on Mars, astrobiology, radiation, fungi, bacteria, radiotolerance
Objavljeno v DiRROS: 03.11.2022; Ogledov: 745; Prenosov: 363
Celotno besedilo (922,44 KB)
Gradivo ima več datotek! Več...

Povzetek: International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm genera, from 51 locations in 32 countries worldwide. Endophytic fungi were characterized by high-throughput sequencing of 352 samples from 145 tree species in 28 countries. Insects were reared from 227 samples of 109 tree species in 18 countries and sorted into taxonomic orders and feeding guilds. Herbivorous insects were grouped into morphospecies and were identified using molecular and morphological approaches. This dataset reveals the diversity of tree-associated taxa, as it contains 12,721 fungal Amplicon Sequence Variants and 208 herbivorous insect morphospecies, sampled across broad geographic and climatic gradients and for many tree species. This dataset will facilitate applied and fundamental studies on the distribution of fungal endophytes and insects in trees.
Ključne besede: diversity, endophytic fungi, endophytic insects, tree twigs
Objavljeno v DiRROS: 01.03.2022; Ogledov: 885; Prenosov: 694
Celotno besedilo (1,32 MB)
Gradivo ima več datotek! Več...