Genus Cortinarius Research Articles

Two new species and a new record of Cortinarius subgenus Telamonia (Agaricales) from India

The genus Cortinarius (Pers.) Gray is one of the dominating mushroom-forming ectomycorrhizal genera in the Indian Himalaya. Cortinarius subgenus Telamonia (Fr.) Trog is the most species-rich group within this genus. In this subgenus, two novel species, namely C. thindii A.Bose & K.Das sp. nov. and C. dhakuricus A.Bose & K.Das sp. nov. (under C. section Hinnulei Melot), and one new record for Indian mycobiota, namely C. pseudotorvus A.Naseer, J.Khan, & A.N.Khalid (under C. section Telamonia (Fr.) Gillot & Lucand), collected from the state of Uttarakhand are presented here with morphological descriptions, illustrations and nrITS-based molecular phylogenetic inferences. Additionally, Cortinarius parvisporus Vizzini is here proposed as nom. nov., for C. brunneocarpus var. microsporus J.Khan.

Ectomycorrhizal fungi and the nitrogen economy of Nothofagus in southern Patagonia.

Subantarctic Nothofagus forests are the southernmost forests in the world, with negligible atmospheric nitrogen (N) deposition. Most paradigms about the role of ectomycorrhizal (ECM) fungi in N cycling and plant N uptake at high latitudes have been tested in boreal coniferous forests, while in the southern hemisphere, ECM hosts are primarily angiosperms. Using ITS1 meta-barcoding, we characterized ECM and saprotrophic fungal communities in evergreen and deciduous Nothofagus forests forming monodominant and mixed stands in the archipelago of Tierra del Fuego (Chile and Argentina). We assessed the N economy of Nothofagus by correlating host species with fungal relative abundances, edaphic variables, net N mineralization, microbial biomass N and the activity of eight extracellular soil enzymes activities. The N economy of deciduous N. pumilio forests was strikingly similar to boreal coniferous forests, with the lowest inorganic N availability and net N mineralization, in correlation to higher relative abundances of ECM fungi with enzymatic capacity for organic N mobilization (genus Cortinarius). In contrast, the N economy of evergreen N. betuloides forests was predominantly inorganic and correlated with ECM lineages from the family Clavulinaceae, in acidic soils with poor drainage. Grassy understory vegetation in deciduous N. antarctica forests likely promoted saprotrophic fungi (i.e., genus Mortierella) in correlation with higher activities of carbon-degrading enzymes. Differences between Nothofagus hosts did not persist in mixed forests, illustrating the range of soil fertility of these ECM angiosperms and the underlying effects of soil and climate on Nothofagus distribution and N cycling in southern Patagonia.

The genus Cortinarius should not (yet) be split

The genus Cortinarius (Agaricales, Basidiomycota) is one of the most species-rich fungal genera, with thousands of species reported. Cortinarius species are important ectomycorrhizal fungi and form associations with many vascular plants globally. Until recently Cortinarius was the single genus of the family Cortinariaceae, despite several attempts to provide a workable, lower-rank hierarchical structure based on subgenera and sections. The first phylogenomic study for this group elevated the old genus Cortinarius to family level and the family was split into ten genera, of which seven were described as new. Here, by careful re-examination of the recently published phylogenomic dataset, we detected extensive gene-tree/species-tree conflicts using both concatenation and multispecies coalescent approaches. Our analyses demonstrate that the Cortinarius phylogeny remains unresolved and the resulting phylogenomic hypotheses suffer from very short and unsupported branches in the backbone. We can confirm monophyly of only four out of ten suggested new genera, leaving uncertain the relationships between each other and the general branching order. Thorough exploration of the tree space demonstrated that the topology on which Cortinarius revised classification relies on does not represent the best phylogenetic hypothesis and should not be used as constrained topology to include additional species. For this reason, we argue that based on available evidence the genus Cortinarius should not (yet) be split. Moreover, considering that phylogenetic uncertainty translates to taxonomic uncertainty, we advise for careful evaluation of phylogenomic datasets before proposing radical taxonomic and nomenclatural changes.

A Study of Metabolites from Basidiomycota and Their Activities against Pseudomonas aeruginosa.

The World Health Organization (WHO) promotes research aimed at developing new drugs from natural compounds. Fungi are important producers of bioactive molecules, and they are often effective against other fungi and/or bacteria and are thus a potential source of new antibiotics. Basidiomycota crude extracts, which have previously been proven to be active against Pseudomonas aeruginosa ATCC27853, were subjected to liquid chromatographic separation by RP-18, leading to six macro-fractions for each fungal extract. The various fractions were tested for their bioactivities against P. aeruginosa ATCC27853, and ten of them were characterized by HPLC-HRMS and NMR. Further chromatographic separations were performed for a few selected macro-fractions, yielding seven pure compounds. Bioactivity was mainly found in the lipophilic fractions containing fatty acids and their derivatives, such as hydroxy or keto C-18 unsaturated acids, and in various complex lipids, such as glycolipids and related compounds. More hydrophilic molecules, such as GABA, phenethylamine, two chromogenic anthraquinoids and pistillarin, were also isolated, and their antibacterial activities were recorded. The novelties of this research are as follows: (i) the genera Cortinarius and Mycena have never been investigated before for the synthesis of antibiotic compounds; (ii) the molecules produced by these genera are known, but their production has never been reported in the investigated fungi; (iii) the determination of bacterial siderophore synthesis inhibition by certain compounds from Cortinarius and Mycena.

Peat loss collocates with a threshold in plant-mycorrhizal associations in drained peatlands encroached by trees.

Drainage-induced encroachment by trees may have major effects on the carbon balance of northern peatlands, and responses of microbial communities are likely to play a central mechanistic role. We profiled the soil fungal community and estimated its genetic potential for the decay of lignin and phenolics (class II peroxidase potential) along peatland drainage gradients stretching from interior locations (undrained, open) to ditched locations (drained, forested). Mycorrhizal fungi dominated the community across the gradients. When moving towards ditches, the dominant type of mycorrhizal association abruptly shifted from ericoid mycorrhiza to ectomycorrhiza at c. 120 m from the ditches. This distance corresponded with increased peat loss, from which more than half may be attributed to oxidation. The ectomycorrhizal genus Cortinarius dominated at the drained end of the gradients and its relatively higher genetic potential to produce class II peroxidases (together with Mycena) was positively associated with peat humification and negatively with carbon-to-nitrogen ratio. Our study is consistent with a plant-soil feedback mechanism, driven by a shift in the mycorrhizal type of vegetation, that potentially mediates changes in aerobic decomposition during postdrainage succession. Such feedback may have long-term legacy effects upon postdrainage restoration efforts and implication for tree encroachment onto carbon-rich soils globally.

Spatial variations in ectomycorrhizal fungi and host tree reciprocal relations are associated with the local distribution patterns of Minjiang fir

Ectomycorrhizal fungi (ECMF) can help maintain the natural range of host trees by assisting their occupancy in the boundary of distribution. However, it is unclear whether the boundary-dependent variations in ECMF communities and their relationships with hosts are associated with the patterns of local-scale host tree distributions. In this study, we investigated the community structure of ECMF in the root tips of the Minjiang fir (Abies fargesii var. faxoniana) saplings, and examined the variations in root-associated ECMF communities and their relationships with the fir saplings along environmental gradients from the centric suitable habitats (SH) on shady slopes to range boundaries (RB) at the upper and lower elevations of the SH and on sunny slopes. We found that both the SH and the upper RB were enriched by the ECMF taxa in the genus Cortinarius, which were positively correlated with the basal diameter (BD) of the firs. In contrast, the lower RB of the shady slopes and the sunny slopes harbored a higher abundance of the ECMF taxa in the genus Tylospora, which were negatively correlated with the BD of the firs. The relationships between the firs and some of the same ECMF species, such as Cortinarius balaustinus and Cortinarius casimiri, shifted from positive at the SH to negative at the lower RB of the shady slopes and on sunny slopes. Soil properties differed between habitat types, so do the relationships of soil properties with ECMF communities. These marginal alterations in ECMF communities and their relationships with the fir saplings were not explainable by changes in soils. Our study highlighted habitat-dependent shifts in root-associated ECMF communities and their correlations with Minjiang fir saplings from suitable habitats to range boundaries. The results suggest that these marginal patterns may be associated with variations in habitats rather than current soil properties for Minjiang firs. The spatial variations in ECMF communities and their relationships with fir saplings could be useful indicators for identification of the site suitability for Minjiang fir regeneration and conservation.

Does wood mulch trigger microbially mediated positive plant-soil feedback in degraded boreal forest sites? A post hoc study.

Reforestation of degraded lands in the boreal forest is challenging and depends on the direction and strength of the plant-soil feedback (PSF). Using a gradient in tree productivity (null, low and high) from a long-term, spatially replicated reforestation experiment of borrow pits in the boreal forest, we investigated the interplay between microbial communities and soil and tree nutrient stocks and concentrations in relation to a positive PSF induced by wood mulch amendment. Three levels of mulch amendment underlie the observed gradient in tree productivity, and plots that had been amended with a continuous layer of mulch 17 years earlier showed a positive PSF with trees up to 6 m tall, a closed canopy, and a developing humus layer. The average taxonomic and functional composition of the bacterial and fungal communities differed markedly betweenlow- and high-productivity plots. Trees in high-productivity plots recruited a specialized soil microbiome that was more efficient at nutrient mobilization and acquisition. These plots showed increases in carbon (C), calcium (Ca), nitrogen (N), potassium (K), and phosphorus (P) stocks and as well as bacterial and fungal biomass. The soil microbiome was dominated by taxa from the fungal genus Cortinarius and the bacterial family Chitinophagaceae, and a complex microbial network with higher connectivity and more keystone species supported tree productivity in reforested plots compared to unproductive plots. Therefore, mulching of plots resulted in a microbially mediated PSF that enhances mineral weathering and non-symbiotic N fixation, and in turn helps transform unproductive plots into productive plots to ensure rapid restoration of the forest ecosystem in a harsh boreal environment.

New Data on Agaricoid and Gasteroid <i>Agaricomycetes</i> in Penza Region (Russia)

The study of agaricoid and gasteroid fungi belonging to the class Agaricomycetes in the Penza region has been carried out beginning with 1976. Due to significant changes in the taxonomy of this group in recent decades, it became necessary to revise the materials accumulated over a 46-year research period. As a result of such a revision, it was found that in the territory of the Penza region, were recorded 837 species of agaricoid and gasteroid fungi of the class Agaricomycetes. They belong to 8 orders, 39 families and 137 genera. The largest families, including more than 50 species, are Agaricaceae, Cortinariaceae, Psathyrellaceae, Russulaceae, Strophariaceae, Tricholomataceae, from 20 to 50 species – Boletaceae, Bolbiticaeae, Crepidotaceae, Entolomataceae, Hygrophoraceae, Marasmiaceae, and Mycenaceae. The remaining families include less than 20 species each. The first place in terms of species richness is occupied by the genus Cortinarius (109 species), the second by the genus Russula (60 species). The genera uniting from 30 to 60 species are Inocybe and Mycena, from 20 to 30 species – Agaricus, Entoloma, Lactarius, Lepiota, Psathyrella, and Tricholoma, from 10 to 20 species – Amanita, Clitocybe, Conocybe, Coprinopsis, Galerina, Hebeloma, Hygrocybe, Hygrophorus, Marasmius, Melanoleuca, Panaeolus, Pholiota. The remaining genera are characterized by lower species richness levels, although they make up 82% of the total species number. Of these, 41 genera include only one species. In the course of research carried out from 2018 to 2022, a total of 27 species of Agaricomycetes new to the region were found. Three of them, Russula groenlandica, R. insignis, and R. melzeri, were noted in Russia for the first time. At the same time, 20 previously discovered species were not confirmed as a result of our revision. During observations from 1976 to 2022, it was found that the number of some species of fungi in the group under consideration is not constant and is subject to changes in the long-term regime. For example, in Agaricus xanthodermus, Caloboletus radicans, Infundibulicybe geotropa, Lactarius semisanguifluus, Lepista personata, Mutinus ravenellii and Rubinoboletus rubinus, this number increases, whereas in Floccularia luteovirens, Lactarius turpis, Leucopaxillus tricolor, Russula chloroides, and Tylopilus felleus, on the contrary, it tends to decrease.

DNA Barcoding Data Reveal Important Overlooked Diversity of Cortinarius sensu lato (Agaricales, Basidiomycota) in the Romanian Carpathians

Cortinarius s.l. is a globally distributed agaricoid genus that has been well studied in Europe with over 1000 described species. However, the information about their taxonomy and diversity in eastern Central Europe is still limited. Only 124 species have been reported so far from Romania, based solely on morphological observations. The aim of this study was to re-examine the diversity of the genus Cortinarius s.l. in the Romanian Carpathian area, employing molecular phylogenetic and morphological methods. During intensive field work in the period 2017–2020, a total of 234 Cortinarius s.l. specimens were collected and studied with integrative taxonomic methods. For all the samples, we amplified and sequenced the nrDNA ITS region, which is the widely used official barcode marker of fungi. These sequences were compared to the data found in public databases (GenBank, UNITE, BOLD). Based on phylogenetic analyses, we identified 109 Cortinarius s.l. species, which represent 40 sections and 3 clades. Out of these species, 43 have previously been documented from Romania based on morphological identification methods, while 66 species are reported as new to the country.

Highlighting the Phototherapeutical Potential of Fungal Pigments in Various Fruiting Body Extracts with Informed Feature-Based Molecular Networking.

Fungal pigments are characterized by a diverse set of chemical backbones, some of which present photosensitizer-like structures. From the genus Cortinarius, for example, several biologically active photosensitizers have been identified leading to the hypothesis that photoactivity might be a more general phenomenon in the kingdom Fungi. This paper aims at testing the hypothesis. Forty-eight fruiting body-forming species producing pigments from all four major biosynthetic pathways (i.e., shikimate-chorismate, acetate-malonate, mevalonate, and nitrogen heterocycles) were selected and submitted to a workflow combining in vitro chemical and biological experiments with state-of-the-art metabolomics. Fungal extracts were profiled by high-resolution mass spectrometry and subsequently explored by spectral organization through feature-based molecular networking (FBMN), including advanced metabolite dereplication techniques. Additionally, the photochemical properties (i.e., light-dependent production of singlet oxygen), the phenolic content, and the (photo)cytotoxic activity of the extracts were studied. Different levels of photoactivity were found in species from all four metabolic groups, indicating that light-dependent effects are common among fungal pigments. In particular, extracts containing pigments from the acetate-malonate pathway, e.g., extracts from Bulgaria inquinans, Daldinia concentrica, and Cortinarius spp., were not only efficient producers of singlet oxygen but also exhibited photocytotoxicity against three different cancer cell lines. This study explores the distribution of photobiological traits in fruiting body forming fungi and highlights new sources for phototherapeutics.

Australian fungi in the genus Cortinarius as a source for new photosensitizers

Australian fungi in the genus Cortinarius as a source for new photosensitizers

Cortinarius kashmirensis sp. nov. in Cortinarius sect. Disjungendi (Agaricales) from Pakistan

During recent fieldwork at Azad Jammu and Kashmir (Pakistan), many basidiomycetes of the genus Cortinarius were collected from mixed coniferous Himalayan temperate forests. Their morphological characterization and phylogenetic analyses based on ITS and LSU sequence data yielded a well-delimited, new species within C. subgenus Telamonia sect Disjungendi. It is characterized by producing small and dry basidiomata with blackish brown conico-convex pilei when young and uplifted at maturity, dark brown lamellae, a fibrillose stipe and small basidiospores (9.4 × 5.5 µm in average).

ВИДОВЕ РІЗНОМАНІТТЯ РОДУ CORTINARIUS (PERS.) GRAY (CORTINARIACEAE) В НПП «ГУЦУЛЬЩИНА»

The genus Cortinarius is one of the largest in the world among lamellar macromycetes, but in Ukraine the species of this genus are insufficiently studied. Тhe article presents the results of mycological studies of the genus Cortinarius during 2010–2020 in the National Natural Park «Hutsulshchyna». The main goal was to study the species composition of the genus Cortinarius in NNP and to identify rare taxa. Field research was carried out on the territory of NNP «Hutsulshchyna» by route-expedition method. As a result, 41 species of the genus Cortinarius were identified, among which one species of C. сaperatus is included in the IUCN lists. The genus under study is a mycorrhizal macromycetes. Among the identified species, 41 % are common in all forest ecosystems, 29 % are highly specialized (associated with specific parterre trees), 8 % grow only in deciduous forests and 10 % – in conifers. The narrowly specialized ones include: Cortinarius flexipes (birch), C. argentatus, C. prasinus (beech), C. purpureus, C. rubellus, C. variicolor (spruce), C. acutus, C. mucosus, C. mucifluoides, C. sanguineus, C. traganus, C. violaceus (pine). The analysis is made: the ratio of the number of species of the genus Cortinarius in the world and in Ukraine, the species richness of the studied genus using the Turing coefficient, the distribution of species by categories of abundance and by affiliation to tree species. The most common species on the territory of NNP «Hutsulshchyna» were: Cortinarius anomalus, C. caerulescens, C. caperatus, C. delibutus, C. multiformis, C. trivialis, C. violaceus. Rare in the NNP include 13 species: Cortinarius camphoratus, C. eburneus, C. hemitrichus, C. flexipes, C. mucifluoides, C. mucosus, C. pholideus, C. praestans, C. prasinus, C. rubellus, C. traganus, C. triumphans, C. variicolor. Іn the Ukrainian Carpathians 19 genus: Cortinarius acutus, C. argentatus, C. armillatus, C. bolaris, C. caerulescens, C. decipiens, C. mucosus, C. hemitrichus, C. flexipes, C. mucifluoides, C. eburneus, C. ochroleucus, C. pholideus, C. praestans, C. prasinus, C. purpureus, C. torvus, C. triumphans, C. trivialis are registered only on the territory of National Natural Park «Hutsulshchyna».

Cortinarius subgenus Leprocybe (Agaricales) in New Zealand

ABSTRACT Cortinarius is the largest genus of Agaricales (mushrooms) in the world with a cosmopolitan distribution. All species are ectomycorrhizal. Cortinariaceae is a very diverse fungal family, recently split into ten genera, one of which is Cortinarius. The former genus Cortinarius s. lato, in its turn, was traditionally divided into 4–7 subgenera, of which one of the later additions is the subgenus Leprocybe. Here we review the diversity of Leprocybe in the Southern Hemisphere. Using a 4-locus molecular phylogeny, it is shown that all but one of M. Moser’s original sections are represented in the South Pacific region, many of them in New Zealand. Several species sharing a morphology that may be designated ‘leprocyboid’ are found in the country. These are discussed, their taxonomy is analysed, and a key is provided. Three new species (Aureonarius ruficollybianus, Cortinarius stenophryx, and Cystinarius pseudoeutactus) are proposed. The leprocyboid Cortinarius sect. Incensi, present in New Zealand, appears not to nest in any of the studied genera, but an analysis with more genes and a wider taxon sampling is required to clarify its position within the phylogeny of the family.

Photochemical defense as trait of fungi from Cortinarius subgenus Dermocybe

The photobiological activity of ten colorful species belonging to subgenus Dermocybe of the basidiomycete genus Cortinarius was investigated. Extracts of all species produced singlet oxygen and are thus photoactive. Pigment analysis was performed and showed similarities of the anthraquinone pigments across the species in dependency to their respective pigmentation types. Detailed content analysis of the pigments in the whole agaricoid fruiting body compared to the three different tissue types (pileus, stipe, and lamellae) revealed that the pigments emodin, dermocybin, and dermorubin, as well as their respective glycosides, are enhanced in the gills. In an independent experiment, the gills were shown to be the most photoactive tissues of the fruiting body. Photobiological experiments with invertebrates (i.e., glassworm Chaoborus crystallinus) proved a phototoxic effect of the methanolic extract of the red blood webcap (Cortinarius sanguineus var. aurantiovaginatus). This work adds further evidence to a common photobiological trait in Cortinarius subgenus Dermocybe and underpins the possibility of a photochemical defense mechanism in fungi.Graphical abstract

Taming the beast: a revised classification of Cortinariaceae based on genomic data

Family Cortinariaceae currently includes only one genus, Cortinarius, which is the largest Agaricales genus, with thousands of species worldwide. The species are important ectomycorrhizal fungi and form associations with many vascular plant genera from tropicals to arctic regions. Genus Cortinarius contains a lot of morphological variation, and its complexity has led many taxonomists to specialize in particular on infrageneric groups. The previous attempts to divide Cortinarius have been shown to be unnatural and the phylogenetic studies done to date have not been able to resolve the higher-level classification of the group above section level. Genomic approaches have revolutionized our view on fungal relationships and provide a way to tackle difficult groups. We used both targeted capture sequencing and shallow whole genome sequencing to produce data and to perform phylogenomic analyses of 75 single-copy genes from 19 species. In addition, a wider 5-locus analysis of 245 species, from the Northern and Southern Hemispheres, was also done. Based on our results, a classification of the family Cortinariaceae into ten genera—Cortinarius, Phlegmacium, Thaxterogaster, Calonarius, Aureonarius, Cystinarius, Volvanarius, Hygronarius, Mystinarius, and Austrocortinarius—is proposed. Seven genera, 10 subgenera, and four sections are described as new to science and five subgenera are introduced as new combinations in a new rank. In addition, 41 section names and 514 species names are combined in new genera and four lecto- and epitypes designated. The position of Stephanopus in suborder Agaricineae remains to be studied. Targeted capture sequencing is used for the first time in fungal taxonomy in Basidiomycetes. It provides a cost-efficient way to produce -omics data in species-rich groups. The -omics data was produced from fungarium specimens up to 21 years old, demonstrating the value of museum specimens in the study of the fungal tree of life. This study is the first family revision in Agaricales based on genomics data and hopefully many others will soon follow.

Links between boreal forest management, soil fungal communities and below‐ground carbon sequestration

Abstract Forest management has a potential to alter below‐ground carbon storage. However, the underlying mechanisms, and the relative importance of carbon input and decomposition in regulation of soil carbon dynamics are poorly understood. We examined whether interactive effects of forest fertilization and thinning on carbon stocks in the topsoil of boreal forests were linked to changes in fungal community composition, biomass and enzyme activities, in a long‐term fertilization and thinning experiment distributed across 29 Pinus sylvestris forests along a 1,300 km latitudinal transect in Sweden. Nitrogen fertilization increased fungal biomass, particularly towards the north and mainly by promoting root‐associated Ascomycetes, but the response was moderated by thinning. Fungal biomass correlated positively with carbon stocks in the organic topsoil. However, ectomycorrhizal Cortinarius species were reduced in abundance by fertilization and correlated negatively with carbon stocks. Plausibly, increased soil carbon stocks after fertilization are linked to increased input of carbon in the form of root‐associated mycelium combined with the loss of ectomycorrhizal decomposers within the genus Cortinarius. These fungal responses to fertilization may mediate a natural climate solution by promoting carbon sequestration in the organic topsoil, but the effect of fertilization may also be undesired from a biodiversity perspective. A free Plain Language Summary can be found within the Supporting Information of this article.

Feature-Based Molecular Networking-An Exciting Tool to Spot Species of the Genus Cortinarius with Hidden Photosensitizers.

Fungi have developed a wide array of defense strategies to overcome mechanical injuries and pathogen infections. Recently, photoactivity has been discovered by showing that pigments isolated from Cortinarius uliginosus produce singlet oxygen under irradiation. To test if this phenomenon is limited to dermocyboid Cortinarii, six colourful Cortinarius species belonging to different classical subgenera (i.e., Dermocybe, Leprocybe, Myxacium, Phlegmacium, and Telamonia) were investigated. Fungal extracts were explored by the combination of in vitro photobiological methods, UHPLC coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS2), feature-based molecular networking (FBMN), and metabolite dereplication techniques. The fungi C. rubrophyllus (Dermocybe) and C. xanthophyllus (Phlegmacium) exhibited promising photobiological activity in a low concentration range (1–7 µg/mL). Using UHPLC-HRMS2-based metabolomic tools, the underlying photoactive principle was investigated. Several monomeric and dimeric anthraquinones were annotated as compounds responsible for the photoactivity. Furthermore, the results showed that light-induced activity is not restricted to a single subgenus, but rather is a trait of Cortinarius species of different phylogenetic lineages and is linked to the presence of fungal anthraquinones. This study highlights the genus Cortinarius as a promising source for novel photopharmaceuticals. Additionally, we showed that putative dereplication of natural photosensitizers can be done by FBMN.

A New High-Throughput-Screening-Assay for Photoantimicrobials Based on EUCAST Revealed Unknown Photoantimicrobials in Cortinariaceae.

Antimicrobial resistance is one of the biggest health and subsequent economic threat humanity faces. Next to massive global awareness campaigns, governments and NGOs alike stress the need for new innovative strategies to treat microbial infections. One of such innovative strategies is the photodynamic antimicrobial chemotherapy (PACT) in which the synergistic effects of photons and drugs are exploited. While many promising reports are available, PACT – and especially the drug-design part behind – is still in its infancy. Common best-practice rules, such as the EUCAST or CLSI protocols for classic antibiotics as well as high-throughput screenings, are missing, and this, in turn, hampers the identification of hit structures. Hit-like structures might come from synthetic approaches or from natural sources. They are identified via activity-guided synthesis or isolation strategies. As source for new antimicrobials, fungi are highly ranked. They share the same ecological niche with many other microbes and consequently established chemical strategies to combat with the others. Recently, in members of the Cortinariaceae, especially of the subgenus Dermocybe, photoactive metabolites were detected. To study their putative photoantimicrobial effect, a photoantimicrobial high-throughput screening (HTS) based on The European Committee on Antimicrobial Susceptibility Testing (EUCAST) was established. After validation, the established HTS was used to evaluate a sample set containing six colorful representatives from the genus Cortinarius (i.e., Cortinarius callisteus, C. rufo-olivaceus, C. traganus, C. trivialis, C. venetus, and C. xanthophyllus). The assay is built on a uniform, light-emitting diode (LED)-based light irradiation across a 96-well microtiter plate, which was achieved by a pioneering arrangement of the LEDs. The validation of the assay was accomplished with well-known photoactive drugs, so-called photosensitizers, utilizing six distinct emission wavelengths (λexc = 428, 478, 523, 598, or 640 nm) and three microbial strains (Candida albicans, Staphylococcus aureus, and Escherichia coli). Evaluating the extracts of six Cortinarius species revealed two highly promising species, i.e., C. rufo-olivaceus and C. xanthophyllus. Extracts from the latter were photoactive against the Gram-positive S. aureus (c = 7.5 μg/ml, H = 30 J/cm2, λ = 478 nm) and the fungus C. albicans (c = 75 μg/ml, H = 30 J/cm2, λ = 478 nm).

Thaxterogaster revisited: A phylogenetic and taxonomic overview of sequestrate Cortinarius from Patagonia

ABSTRACT In the Patagonian region, Cortinarius is the most diverse and abundant genus of ectomycorrhizal fungi with at least 250 species. Sequestrate forms were until recently documented within the genus Thaxterogaster, a genus now known to be polyphyletic, and many were consequently transferred to Cortinarius. Original descriptions were mostly available in German and Spanish and interpretations of morphological structures outdated. Despite recent advances in Cortinarius systematics, the current classification, diversity, and ecology of sequestrate “cortinarioid” fungi in Patagonia remain unclear. The objective of this study was to provide an update on sequestrate Cortinarius of southern South America. We documented each species with morphological descriptions, photographs, basidiospore scanning electron microscopy (SEM) images, and molecular characterization using nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and nuc 28S rDNA (28S) sequence data. Original descriptions of taxa were also translated to English and revised based on fresh collections. We documented 24 species from Patagonia based on molecular data and conducted morphological and phylogenetic analysis for 18 previously described species based on type and reference specimens. In addition, we formally described two new species. Four additional taxa were provisionally determined as new but require further study. New ITS sequence data were produced from eight type specimens. We also provide a new name, Cortinarius gloiodes, nom. nov., for the taxon previously described as Thaxterogaster gliocyclus. In addition to the species treated in detail, we provided additional reference information and discussion on six described species that remained incompletely known or for which no recent collections were found. Of the 24 taxa documented from Patagonia, 15 species were assigned to 12 current sections in the genus Cortinarius. Analysis of spore ultrastructure showed that sequestrate forms of Patagonian Cortinarius lack a true perisporium.