Antarctic rocks from continental Antarctica as source of potential human opportunistic fungi

Fungal and fungal-like diversity present in ornithogenically influenced maritime Antarctic soils assessed using metabarcoding

We assessed soil fungal and fungal-like diversity using metabarcoding in ornithogenically influenced soils around nests of the bird species Phalacrocorax atriceps, Macronectes giganteus, Pygoscelis antarcticus, and Pygoscelis adelie on the South Shetland Islands, maritime Antarctic. A total of 1,392,784 fungal DNA reads was obtained and assigned to 186 amplicon sequence variants (ASVs). The dominant fungal phylum was Ascomycota, followed by Basidiomycota, Chytridiomycota, Blastocladiomycota, Rozellomycota, Mortierellomycota, Monoblepharomycota, Aphelidiomycota, Basidiobolomycota, Mucoromycota, and the fungal-like Oomycota (Stramenopila), in rank order. Antarctomyces sp., Blastocladiomycota sp., Pseudogymnoascus pannorum, Microascaceae sp., Mortierella sp., Lobulomycetales sp., Sordariomycetes sp., Fungal sp., Rhizophydiales sp., Pseudeurotiaceae sp., Chytridiomycota sp. 1, Filobasidiella sp., Tausonia pullulans, Betamyces sp., and Leucosporidium sp. were the most abundant assigned taxa. The fungal assemblages present in the different ornithogenically influenced soils displayed different diversity indices. However, in general, we detected high fungal diversity and few taxa shared between the samples. Despite the polyextreme environmental conditions experienced in these Antarctic soils, the metabarcoding approach detected a rich and complex fungal community dominated by saprophytes, but with some pathogenic taxa also present. The community was dominated by psychrophilic and psychrotolerant taxa, some apparently endemic to Antarctica, and those identified only at higher taxonomic levels, which may represent currently undescribed fungi. The mycobiome detected included taxa characterized by different ecological roles, including saprotrophic, human- and animal-associated, phytopathogenic, mutualistic, and cosmopolitan. These fungi may potentially be dispersed by birds or in the air column over great distances, including between different regions within Antarctica and from South America, Africa, and Oceania.

Endolithic Fungal Diversity in Antarctic Oligocene Rock Samples Explored Using DNA Metabarcoding

In this study, we evaluated the fungal diversity present associated with cores of Oligocene rocks using a DNA metabarcoding approach. We detected 940,969 DNA reads grouped into 198 amplicon sequence variants (ASVs) representing the phyla Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota, Mucoromycota, Rozellomycota, Blastocladiomycota, Monoblepharomycota, Zoopagomycota, Aphelidiomycota (Fungi) and the fungal-like Oomycota (Stramenopila), in rank abundance order. Pseudogymnoascus pannorum, Penicillium sp., Aspergillus sp., Cladosporium sp., Aspergillaceae sp. and Diaporthaceae sp. were assessed to be dominant taxa, with 22 fungal ASVs displaying intermediate abundance and 170 being minor components of the assigned fungal diversity. The data obtained displayed high diversity indices, while rarefaction indicated that the majority of the diversity was detected. However, the diversity indices varied between the cores analysed. The endolithic fungal community detected using a metabarcoding approach in the Oligocene rock samples examined contains a rich and complex mycobiome comprising taxa with different lifestyles, comparable with the diversity reported in recent studies of a range of Antarctic habitats. Due to the high fungal diversity detected, our results suggest the necessity of further research to develop strategies to isolate these fungi in culture for evolutionary, physiological, and biogeochemical studies, and to assess their potential role in biotechnological applications.

Trends in Antarctic soil fungal research in the context of environmental changes

Antarctic soils represent one of the most pristine environments on Earth, where highly adapted and often endemic microbial species withstand multiple extremes. Specifically, fungal diversity is extremely low in Antarctic soils and species distribution and diversity are still not fully characterized in the continent. Despite the unique features of this environment and the international interest in its preservation, several factors pose severe threats to the conservation of inhabiting ecosystems. In this light, we aimed to provide an overview of the effects on fungal communities of the main changes endangering the soils of the continent. Among these, the increasing human presence, both for touristic and scientific purposes, has led to increased use of fuels for transport and energy supply, which has been linked to an increase in unintentional environmental contamination. It has been reported that several fungal species have evolved cellular processes in response to these soil contamination episodes, which may be exploited for restoring contaminated areas at low temperatures. Additionally, the effects of climate change are another significant threat to Antarctic ecosystems, with the expected merging of previously isolated ecosystems and their homogenization. A possible reduction of biodiversity due to the disappearance of well-adapted, often endemic species, as well as an increase of biodiversity, due to the spreading of non-native, more competitive species have been suggested. Despite some studies describing the specialization of fungal communities and their correlation with environmental parameters, our comprehension of how soil communities may respond to these changes remains limited. The majority of studies attempting to precisely define the effects of climate change, including in situ and laboratory simulations, have mainly focused on the bacterial components of these soils, and further studies are necessary, including the other biotic components.

Pathogenic potential of an environmental Aspergillus fumigatus strain recovered from soil of Pygoscelis papua (Gentoo penguins) colony in Antarctica

Aspergillus fumigatus is a common opportunistic pathogen in different animals, including birds such as penguins. For the first time, a fungal strain identified as A. fumigatus was isolated from soil in the nests of gentoo penguins, Pygoscelis papua, on Livingston Island, South Shetland Islands (maritime Antarctica). This isolate (A. fumigatus UFMGCB 11829) displayed a series of potentially pathogenic characteristics in vitro. We evaluated its detailed molecular taxonomy and submitted the A. fumigatus UFMGCB 11829 Antarctic strain to in vivo pathogenic modelling. The isolate was confirmed to represent A. fumigatus morphological and phylogenetic analysis showed that it was closely related to A. fumigatus sequences reported from animals, immunosuppressed humans, storage grains, plants and soils. The strain displayed the best mycelial growth and conidia production at 37 ºC; however, it was also able to grow and produce conidia at 15º, demonstrating its capability to survive and colonize penguin nest at least in the summer season in maritime Antarctica. In pathogenicity tests, healthy mice did not showed symptoms of infection; however, 50% lethality was observed in immunosuppressed mice that were inoculated with 106 and 107 spores. Lethality increased to 100% when inoculated with 108 spores. Our data highlight the potential pathogenicity of opportunistic A. fumigatus that may be present in the Antarctic, and the risks of both their further transfer within Antarctica and outwards to other continents, risks which may be exacerbated due global climatic changes.

Redisposition of acremonium-like fungi in Hypocreales

Acremonium is acknowledged as a highly ubiquitous genus including saprobic, parasitic, or endophytic fungi that inhabit a variety of environments. Species of this genus are extensively exploited in industrial, commercial, pharmaceutical, and biocontrol applications, and proved to be a rich source of novel and bioactive secondary metabolites. Acremonium has been recognised as a taxonomically difficult group of ascomycetes, due to the reduced and high plasticity of morphological characters, wide ecological distribution and substrate range. Recent advances in molecular phylogenies, revealed that Acremonium is highly polyphyletic and members of Acremonium s. lat. belong to at least three distinct orders of Sordariomycetes, of which numerous orders, families and genera with acremonium-like morphs remain undefined. To infer the phylogenetic relationships and establish a natural classification for acremonium-like taxa, systematic analyses were conducted based on a large number of cultures with a global distribution and varied substrates. A total of 633 cultures with acremonium-like morphology, including 261 ex-type cultures from 89 countries and a variety of substrates including soil, plants, fungi, humans, insects, air, and water were examined. An overview phylogenetic tree based on three loci (ITS, LSU, rpb2) was generated to delimit the orders and families. Separate trees based on a combined analysis of four loci (ITS, LSU, rpb2, tef-1α) were used to delimit species at generic and family levels. Combined with the morphological features, host associations and ecological analyses, acremonium-like species evaluated in the present study are currently assigned to 63 genera, and 14 families in Cephalothecales, Glomerellales and Hypocreales, mainly in the families Bionectriaceae, Plectosphaerellaceae and Sarocladiaceae and five new hypocrealean families, namely Chrysonectriaceae, Neoacremoniaceae, Nothoacremoniaceae, Pseudoniessliaceae and Valsonectriaceae. Among them, 17 new genera and 63 new combinations are proposed, with descriptions of 65 new species. Furthermore, one epitype and one neotype are designated to stabilise the taxonomy and use of older names. Results of this study demonstrated that most species of Acremonium s. lat. grouped in genera of Bionectriaceae, including the type A. alternatum. A phylogenetic backbone tree is provided for Bionectriaceae, in which 183 species are recognised and 39 well-supported genera are resolved, including 10 new genera. Additionally, rpb2 and tef-1α are proposed as potential DNA barcodes for the identification of taxa in Bionectriaceae. Taxonomic novelties: New families: Chrysonectriaceae L.W. Hou, L. Cai & Crous, Neoacremoniaceae L.W. Hou, L. Cai & Crous, Nothoacremoniaceae L.W. Hou, L. Cai & Crous, Pseudoniessliaceae L.W. Hou, L. Cai & Crous, Valsonectriaceae L.W. Hou, L. Cai & Crous. New genera: Bionectriaceae: Alloacremonium L.W. Hou, L. Cai & Crous, Gossypinidium L.W. Hou, L. Cai & Crous, Monohydropisphaera L.W. Hou, L. Cai & Crous, Musananaesporium L.W. Hou, L. Cai & Crous, Paragliomastix L.W. Hou, L. Cai & Crous, Proliferophialis L.W. Hou, L. Cai & Crous, Proxiovicillium L.W. Hou, L. Cai & Crous, Ramosiphorum L.W. Hou, L. Cai & Crous, Verruciconidia L.W. Hou, L. Cai & Crous, Waltergamsia L.W. Hou, L. Cai & Crous; Clavicipitaceae: Subuliphorum L.W. Hou, L. Cai & Crous; Neoacremoniaceae: Neoacremonium L.W. Hou, L. Cai & Crous; Nothoacremoniaceae: Nothoacremonium L.W. Hou, L. Cai & Crous; Plectosphaerellaceae: Allomusicillium L.W. Hou, L. Cai & Crous, Parafuscohypha L.W. Hou, L. Cai & Crous; Pseudoniessliaceae: Pseudoniesslia L.W. Hou, L. Cai & Crous; Sarocladiaceae: Polyphialocladium L.W. Hou, L. Cai & Crous. New species: Bionectriaceae: Alloacremonium ferrugineum L.W. Hou, L. Cai & Crous, Al. humicola L.W. Hou, L. Cai & Crous, Acremonium aerium L.W. Hou, L. Cai & Crous, A. brunneisporum L.W. Hou, L. Cai & Crous, A. chlamydosporium L.W. Hou, L. Cai & Crous, A. ellipsoideum L.W. Hou, Rämä, L. Cai & Crous, A. gamsianum L.W. Hou, L. Cai & Crous, A. longiphialidicum L.W. Hou, L. Cai & Crous, A. multiramosum L.W. Hou, Rämä, L. Cai & Crous, A. mycoparasiticum L.W. Hou, L. Cai & Crous, A. stroudii K. Fletcher, F.C. Küpper & P. van West, A. subulatum L.W. Hou, L. Cai & Crous, A. synnematoferum L.W. Hou, Rämä, L. Cai & Crous, Bulbithecium ammophilae L.W. Hou, L. Cai & Crous, B. ellipsoideum L.W. Hou, L. Cai & Crous, B. truncatum L.W. Hou, L. Cai & Crous, Emericellopsis brunneiguttula L.W. Hou, L. Cai & Crous, Gliomastix musae L.W. Hou, L. Cai & Crous, Gossypinidium sporodochiale L.W. Hou, L. Cai & Crous, Hapsidospora stercoraria L.W. Hou, L. Cai & Crous, H. variabilis L.W. Hou, L. Cai & Crous, Mycocitrus odorus L.W. Hou, L. Cai & Crous, Nectriopsis ellipsoidea L.W. Hou, L. Cai & Crous, Paracylindrocarpon aurantiacum L.W. Hou, L. Cai & Crous, Pn. foliicola Lechat & J. Fourn., Paragliomastix rosea L.W. Hou, L. Cai & Crous, Proliferophialis apiculata L.W. Hou, L. Cai & Crous, Protocreopsis finnmarkica L.W. Hou, L. Cai, Rämä & Crous, Proxiovicillium lepidopterorum L.W. Hou, L. Cai & Crous, Ramosiphorum echinoporiae L.W. Hou, L. Cai & Crous, R. polyporicola L.W. Hou, L. Cai & Crous, R. thailandicum L.W. Hou, L. Cai & Crous, Verruciconidia erythroxyli L.W. Hou, L. Cai & Crous, Ve. infuscata L.W. Hou, L. Cai & Crous, Ve. quercina L.W. Hou, L. Cai & Crous, Ve. siccicapita L.W. Hou, L. Cai & Crous, Ve. unguis L.W. Hou, L. Cai & Crous, Waltergamsia alkalina L.W. Hou, L. Cai & Crous, W. catenata L.W. Hou, L. Cai & Crous, W. moroccensis L.W. Hou, L. Cai & Crous, W. obpyriformis L.W. Hou, L. Cai & Crous; Chrysonectriaceae: Chrysonectria crystallifera L.W. Hou, L. Cai & Crous; Nectriaceae: Xenoacremonium allantoideum L.W. Hou, L. Cai & Crous; Neoacremoniaceae: Neoacremonium distortum L.W. Hou, L. Cai & Crous, N. flavum L.W. Hou, L. Cai & Crous; Nothoacremoniaceae: Nothoacremonium subcylindricum L.W. Hou, L. Cai & Crous, No. vesiculophorum L.W. Hou, L. Cai & Crous; Myrotheciomycetaceae: Trichothecium hongkongense L.W. Hou, L. Cai & Crous; Plectosphaerellaceae: Brunneomyces polyphialidus L.W. Hou, L. Cai & Crous, Parafuscohypha proliferata L.W. Hou, L. Cai & Crous; Sarocladiaceae: Chlamydocillium acaciae L.W. Hou, L. Cai & Crous, C. antarcticum L.W. Hou, L. Cai & Crous, C. guttulatum L.W. Hou, L. Cai & Crous, C. lolii L.W. Hou, L. Cai & Crous, C. soli L.W. Hou, L. Cai & Crous, C. terrestre L.W. Hou, L. Cai & Crous, Parasarocladium chondroidum L.W. Hou, L. Cai & Crous,Polyphialocladium fusisporum L.W. Hou, L. Cai & Crous, Sarocladium agarici L.W. Hou, L. Cai & Crous, S. citri L.W. Hou, L. Cai & Crous, S. ferrugineum L.W. Hou, L. Cai & Crous, S. fuscum L.W. Hou, L. Cai & Crous,S. theobromae L.W. Hou, L. Cai & Crous; Valsonectriaceae: Valsonectria crystalligena L.W. Hou, L. Cai & Crous, V. hilaris L.W. Hou, L. Cai & Crous. New combinations: Bionectriaceae: Acremonium purpurascens (Sukapure & Thirum.) L.W. Hou, L. Cai & Crous, Bulbithecium arxii (Malloch) L.W. Hou, L. Cai & Crous, Bu. borodinense (Tad. Ito et al.) L.W. Hou, L. Cai & Crous, Bu. pinkertoniae (W. Gams) L.W. Hou, L. Cai & Crous, Bu. spinosum (Negroni) L.W. Hou, L. Cai & Crous, Emericellopsis exuviara (Sigler et al.) L.W. Hou, L. Cai & Crous, E. fimetaria (Pers.) L.W. Hou, L. Cai & Crous, E. fuci (Summerb. et al.) L.W. Hou, L. Cai & Crous, E. moniliformis (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, E. salmonea (W. Gams & Lodha) L.W. Hou, L. Cai & Crous, E. tubakii (Gams) L.W. Hou, L. Cai & Crous, Fusariella arenula (Berk. & Broome) L.W. Hou, L. Cai & Crous, Hapsidospora chrysogena (Thirum. & Sukapure) L.W. Hou, L. Cai & Crous, H. flava (W. Gams) L.W. Hou, L. Cai & Crous, H. globosa (Malloch & Cain) L.W. Hou, L. Cai & Crous, H. inversa (Malloch & Cain) L.W. Hou, L. Cai & Crous, Hydropisphaera aurantiaca (C.A. Jørg.) L.W. Hou, L. Cai & Crous, Lasionectria atrorubra (Lechat & J. Fourn.) L.W. Hou, L. Cai & Crous, L. bisepta (W. Gams) L.W. Hou, L. Cai & Crous, L. castaneicola (Lechat & Gardiennet) L.W. Hou, L. Cai & Crous, L. cerealis (P. Karst.) L.W. Hou, L. Cai & Crous, L. olida (W. Gams) L.W. Hou, L. Cai & Crous, Lasionectriopsis dentifera (Samuels) L.W. Hou, L. Cai & Crous, Lasionectriella arenuloides (Samuels) L.W. Hou, L. Cai & Crous, La. marigotensis (Lechat & J. Fourn.) L.W. Hou, L. Cai & Crous, Monohydropisphaera fusigera (Berk. & Broome) L.W. Hou, L. Cai & Crous, Musananaesporium tectonae (R.F. Castañeda) L.W. Hou, L. Cai & Crous, Mycocitrus zonatus (Sawada) L.W. Hou, L. Cai & Crous, Nectriopsis microspora (Jaap) L.W. Hou, L. Cai & Crous, Ovicillium asperulatum (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, O. variecolor (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, Paracylindrocarpon multiloculatum (Samuels) L.W. Hou, L. Cai & Crous, Pn. multiseptatum (Samuels)L.W. Hou, L. Cai & Crous, Paragliomastix chiangraiensis (J.F. Li et al.) L.W. Hou, L. Cai & Crous, Px. luzulae (Fuckel) L.W. Hou, L. Cai & Crous, Px. znieffensis (Lechat & J. Fourn.) L.W. Hou, L. Cai & Crous, Protocreopsis rutila (W. Gams) L.W. Hou, L. Cai & Crous, Proxiovicillium blochii (Matr.)L.W. Hou, L. Cai & Crous, Stanjemonium dichromosporum (Gams & Sivasith.) L.W. Hou, L. Cai & Crous, Verruciconidia persicina (Nicot) L.W. Hou, L. Cai & Crous, Ve. verruculosa (W. Gams & Veenb.-Rijks) L.W. Hou, L. Cai & Crous, Waltergamsia citrina (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. dimorphospora (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. epimycota (Samuels) L.W. Hou, L. Cai & Crous, W. fusidioides (Nicot) L.W. Hou, L. Cai & Crous, W. hennebertii (W. Gams) L.W. Hou, L. Cai & Crous, W. parva (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. pilosa (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. zeylanica (Petch) L.W. Hou, L. Cai & Crous; Cephalothecaceae: Phialemonium thermophilum (W. Gams & J. Lacey) L.W. Hou, L. Cai & Crous; Clavicipitaceae: Subuliphorum camptosporum (W. Gams) L.W. Hou, L. Cai & Crous; Coniochaetaceae: Coniochaeta psammospora (W. Gams) L.W. Hou, L. Cai & Crous; Nothoacremoniaceae: Nothoacremonium exiguum (W. Gams) L.W. Hou, L. Cai & Crous; Neoacremoniaceae: Neoacremonium minutisporum (Sukapure & Thirum.) L.W. Hou, L. Cai & Crous; Ne. taiwanense (K.L. Pang et al.) L.W. Hou, L. Cai & Crous; Ne. vitellinum (W. Gams) L.W. Hou, L. Cai & Crous; Plectosphaerellaceae: Allomusicillium domschii (W. Gams) L.W. Hou, L. Cai & Crous, Brunneomyces pseudozeylanicus (W. Gams) L.W. Hou, L. Cai & Crous; Pseudoniessliaceae: Pseudoniesslia minutispora (W. Gams et al.) L.W. Hou, L. Cai & Crous; Sarocladiaceae: Chlamydocillium curvulum (W. Gams) L.W. Hou, L. Cai & Crous, Parasarocladium funiculosum (Sukapure & Thirum.) L.W. Hou, L. Cai & Crous; Valsonectriaceae: Valsonectria inflata (C.H. Dickinson) L.W. Hou, L. Cai & Crous, V. roseola (G. Sm.) L.W. Hou, L. Cai & Crous. Epitype (basionym): Sphaeria violacea J.C. Schmidt ex Fr. Neotype (basionym): Mastigocladium blochii Matr. Citation: Hou LW, Giraldo A, Groenewald JZ, Rämä T, Summerbell RC, Zang P, Cai L, Crous PW (2023). Redisposition of acremonium-like fungi in Hypocreales. Studies in Mycology 105: 23-203. doi: 10.3114/sim.2023.105.02.

Rock-inhabiting fungi: terminology, diversity, evolution and adaptation mechanisms

Rock-inhabiting fungi (RIF) constitute an ecological group associated with terrestrial rocks. This association is generally restricted to the persistent colonisation of rocks and peculiar morphological features based on melanisation and slow growth, which endow RIF with significance in eukaryotic biology, special status in ecology, and exotic potential in biotechnology. There is a need to achieve a better understanding of the hidden biodiversity, antistress biology, origin and convergent evolution of RIF, which will facilitate cultural relic preservation, exploitation of the biogeochemical cycle of rock elements and biotechnology applications. This review focuses on summarising the current knowledge of rock-inhabiting fungi, with particular reference to terminology, biodiversity and geographic distribution, origin and evolution, and stress adaptation mechanisms. We especially teased out the definition through summing up the terms related to rock-inhabting fungi, and also provided a checklist of rock-inhabiting fungal taxa recorded following updated classification schemes.

Fungal diversity present on rocks from a polar desert in continental Antarctica assessed using DNA metabarcoding

We evaluated the fungal diversity associated with carbonate veins and two types of salt encrustation in rocks in a polar desert region of continental Antarctica using DNA a metabarcoding approach. We detected 262,268 reads grouped into 517 amplicon sequence variants (ASVs) assigned to the phyla Ascomycota, Basidiomycota, Mortierellomycota and Mucoromycota. Fourteen ASVs belonging to the genera Trichosporon, Mortierella, Penicillium, Aspergillus, Cladosporium, Coprinellus, Pleurotus and Pseudogymnoascus were assessed to be dominant taxa. The fungal communities of the three habitats sampled displayed high diversity indices when compared with other habitats of Antarctica, although differing in detail, with the highest diversity indices in the gypsum crust type 2. Only 48 of the 517 ASVs (9.28%) were detected in all three habitats, including dominant, intermediate and minor components. In contrast with previous studies of fungal communities living in the ultra-extreme conditions of continental Antarctica, application of metabarcoding revealed the DNA of a rich and complex resident fungal community. The ASVs detected included fungi with different ecological roles, with xerophilic, human- and animal-associated, phytopathogenic, saprotrophic, mutualistic, psychrotolerant and cosmopolitan taxa. This sequence diversity may be the result of deposition of fungal propagules over time driven by air currents, precipitation or human activities in the region.

Beyond the extremes: Rocks as ultimate refuge for fungi in drylands

In an era of rapid climate change and expansion of desertification, the extremely harsh conditions of drylands are a true challenge for microbial life. Under drought conditions, where most life forms cannot survive, rocks represent the main refuge for life. Indeed, the endolithic habitat provides thermal buffering, physical stability, and protection against incident ultraviolet (UV) radiation and solar radiation and, to some extent, ensures water retention to microorganisms. The study of these highly specialized extreme-tolerant and extremophiles may provide tools for understanding microbial interactions and processes that allow them to keep their metabolic machinery active under conditions of dryness and oligotrophy that are typically incompatible with active life, up to the dry limits for life. Despite lithobiontic communities being studied all over the world, a comprehensive understanding of their ecology, evolution, and adaptation is still nascent. Herein, we survey the fungal component of these microbial ecosystems. We first provide an overview of the main defined groups (i.e., lichen-forming fungi, black fungi, and yeasts) of the most known and studied Antarctic endolithic communities that are almost the only life forms ensuring ecosystem functionality in the ice-free areas of the continent. For each group, we discuss their main traits and their diversity. Then, we focus on the fungal taxonomy and ecology of other worldwide endolithic communities. Finally, we highlight the utmost importance of a global rock survey in order to have a comprehensive view of the diversity, distribution, and functionality of these fungi in drylands, to obtain tools in desert area management, and as early alarm systems to climate change.

Sarocladium and Acremonium infections: New faces of an old opportunistic fungus

The genera Acremonium and Sarocladium comprise a high diversity of morphologically and genetically related fungi generally found in the environment, although a few species, mainly Sarocladium kiliense and Acremonium egyptiacum, can also be involved in many human infections. Clinical management of opportunistic infections caused by these fungi is very complex, since their correct identification is unreliable, and they generally show poor antifungal response. More than 300 clinical cases involving a broad range of Acremonium/Sarocladium infections have so far been published, and with this review we aim to compile and provide a detailed overview of the current knowledge on Acremonium/Sarocladium human infections in terms of presentation, diagnosis, treatments and prognoses. We also aim to summarise and discuss the data currently available on their antifungal susceptibility, emphasising the promising results obtained with voriconazole as well as their impact in terms of animal infections.

Strong variance in the inflammatory and cytotoxic potentials of Penicillium and Aspergillus species from cleaning workers' exposure in nursing homes

Penicillium and Aspergillus are among the dominant genera of fungi in many environments. Exposure to these fungi may cause inflammation-related health effects, however the knowledge about this at species level is limited. The aim of this study was to obtain knowledge about cleaning workers' exposure to fungi and to investigate the total inflammatory potential (TIP) and the cytotoxic potential of fungal species. The fungi were obtained from the personal exposure of cleaning workers' in five nursing homes. In total 271 fungal isolates were identified using MALDI-TOF MS. The TIP and cytotoxic potential were determined for 30 different fungal isolates covering 17 species in an in vitro assay by exposing HL-60 cells to the fungal spores of each isolate. The geometric mean exposure of the cleaning workers was 351 CFU fungi/m³ air. We showed that the TIP and cytotoxicity varied among both species and isolates. At the two lowest doses, there was a positive relationship between spore concentration and TIP. The species with highest TIPs were A. candidus and P. italicum, while the most cytotoxic ones were A. niger and A. fumigatus. There was no obvious relationship between the TIP of an isolate and its cytotoxicity. The results of this study provide a better understanding of the inflammatory potential and cytotoxicity of different environmental fungal species and contribute to the risk evaluation of exposure to different Penicillium and Aspergillus species.

Fungi in glacial ice of Antarctica: diversity, distribution and bioprospecting of bioactive compounds

We identified cultivable fungi present in the glacial ice fragments collected in nine sites across Antarctica Peninsula and assessed their abilities to produce bioactive compounds. Three ice fragments with approximately 20 kg were collected, melted and 3 L filtered through of 0.45 µm sterilized membranes, which were placed on the media Sabouraud agar and minimal medium incubated at 10 °C. We collected 66 isolates classified into 27 taxa of 14 genera. Penicillium palitans, Penicillium sp. 1, Thelebolus balaustiformis, Glaciozyma antarctica, Penicillium sp. 7, Rhodotorula mucilaginosa, and Rhodotorula dairenensis had the highest frequencies. The diversity and richness of the fungal community were high with moderate dominance. Penicillium species were present in all samples, with Penicillium chrysogenum showing the broadest distribution. P. chrysogenum, P. palitans, and Penicillium spp. had trypanocidal, leishmanicidal, and herbicidal activities, with P. chrysogenum having the broadest and highest capability. ¹H NMR signals revealed the presence of highly functionalized secondary metabolites in the bioactive extracts. Despite extreme environmental conditions, glacial ice harbours a diverse fungal community, including species never before recorded in the Arctic and Antarctica. Among them, Penicillium taxa may represent wild fungal strains with genetic and biochemical pathways that may produce new secondary bioactive metabolites.

Contributions of Spore Secondary Metabolites to UV-C Protection and Virulence Vary in Different Aspergillus fumigatus Strains

Fungal spores contain secondary metabolites that can protect them from a multitude of abiotic and biotic stresses. Conidia (asexual spores) of the human pathogen Aspergillus fumigatus synthesize several metabolites, including melanin, which has been reported to be important for virulence in this species and to be protective against UV radiation in other fungi. Here, we investigate the role of melanin in diverse isolates of A. fumigatus and find variability in its ability to protect spores from UV-C radiation or impact virulence in a zebrafish model of invasive aspergillosis in two clinical strains and one ISS strain. Further, we assess the role of other spore metabolites in a clinical strain of A. fumigatus and identify fumiquinazoline as an additional UV-C-protective molecule but not a virulence determinant. The results show differential roles of secondary metabolites in spore protection dependent on the environmental stress and strain of A. fumigatus. As protection from elevated levels of radiation is of paramount importance for future human outer space explorations, the discovery of small molecules with radiation-protective potential may result in developing novel safety measures for astronauts.

Fungi are versatile organisms which thrive in hostile environments, including the International Space Station (ISS). Several isolates of the human pathogen Aspergillus fumigatus have been found contaminating the ISS, an environment with increased exposure to UV radiation. Secondary metabolites (SMs) in spores, such as melanins, have been shown to protect spores from UV radiation in other fungi. To test the hypothesis that melanin and other known spore SMs provide UV protection to A. fumigatus isolates, we subjected SM spore mutants to UV-C radiation. We found that 1,8-dihydroxynaphthalene (DHN)-melanin mutants of two clinical A. fumigatus strains (Af293 and CEA17) but not an ISS-isolated strain (IF1SW-F4) were more sensitive to UV-C than their respective wild-type (WT) strains. Because DHN-melanin has been shown to shield A. fumigatus from the host immune system, we examined all DHN mutants for virulence in the zebrafish model of invasive aspergillosis. Following recent studies highlighting the pathogenic variability of different A. fumigatus isolates, we found DHN-melanin to be a virulence factor in CEA17 and IF1SW-F4 but not Af293. Three additional spore metabolites were examined in Af293, where fumiquinazoline also showed UV-C-protective properties, but two other spore metabolites, monomethylsulochrin and fumigaclavine, provided no UV-C-protective properties. Virulence tests of these three SM spore mutants indicated a slight increase in virulence of the monomethylsulochrin deletion strain. Taken together, this work suggests differential roles of specific spore metabolites across Aspergillus isolates and by types of environmental stress.

Cultivable fungi present in deep-sea sediments of Antarctica: taxonomy, diversity, and bioprospecting of bioactive compounds

We accessed the culturable mycobiota present in marine sediments at different depths in Antarctica Ocean. Acremonium fusidioides, Penicillium allii-sativi, Penicillium chrysogenum, Penicillium palitans, Penicillium solitum, and Pseudogymnoascus verrucosus were identified. Penicillium allii-sativi was the dominant species. At least one isolate of each species was capable to present antifungal, trypanocidal, leishmanicidal, antimalarial, nematocidal, or herbicidal activities. Penicillium produced extracts with strong trypanocidal and antimalarial activities, and the extracts of P. solitum and P. chrysogenum demonstrated strong antimalarial activities. Acremonium fusidioides and P. verrucosus displayed strong selective herbicidal properties. The ¹H NMR signals for extracts of A. fusidioides, P. chrysogenum, and P. solitum indicated the presence of highly functionalized secondary metabolites, which may be responsible for the biological activities detected. In the deep marine Antarctic sediments, we detected fungal assemblages in which the Penicillium species were found to be dominant and demonstrated capabilities to survive and/or colonise that poly-extreme habitat. Penicillium being a polyextremophile Antarctic species, exhibited strong biological activities and the presence of aromatic compounds in its extracts may indicate that they are wild ancient strains with high genetic and biochemical potentials that enable them to produce bioactive compounds which can be researched in further studies and used in the chemotherapy of neglected tropical diseases as well as in agriculture.

Diversity, Distribution, and Ecology of Fungi in the Seasonal Snow of Antarctica

We characterized the fungal community found in the winter seasonal snow of the Antarctic Peninsula. From the samples of snow, 234 fungal isolates were obtained and could be assigned to 51 taxa of 26 genera. Eleven yeast species displayed the highest densities; among them, Phenoliferia glacialis showed a broad distribution and was detected at all sites that were sampled. Fungi known to be opportunistic in humans were subjected to antifungal minimal inhibition concentration. Debaryomyces hansenii, Rhodotorula mucilaginosa, Penicillium chrysogenum, Penicillium sp. 3, and Penicillium sp. 4 displayed resistance against the antifungals benomyl and fluconazole. Among them, R. mucilaginosa isolates were able to grow at 37 °C. Our results show that the winter seasonal snow of the Antarctic Peninsula contains a diverse fungal community dominated by cosmopolitan ubiquitous fungal species previously found in tropical, temperate, and polar ecosystems. The high densities of these cosmopolitan fungi suggest that they could be present in the air that arrives at the Antarctic Peninsula by air masses from outside Antarctica. Additionally, we detected environmental fungal isolates that were resistant to agricultural and clinical antifungals and able to grow at 37 °C. Further studies will be needed to characterize the virulence potential of these fungi in humans and animals.

The diversity, distribution, and pathogenic potential of cultivable fungi present in rocks from the South Shetlands archipelago, Maritime Antarctica

We studied the molecular taxonomy and diversity of cultivable rock fungi from Antarctic islands. From 50 rock samples, 386 fungal isolates were obtained and identified as 33 taxa of 20 genera. The genera Cladophialophora, Cladosporium, Cyphellophora, Eichleriella, Paracladophialophora, and Penicillium displayed the highest densities. Ecological diversity indices showed that the fungal assemblages are diverse and rich with low dominance. The genera Cladophialophora, Cladosporium, and Penicillium showed a broad distribution from rocks of the various islands. One hundred and fifty-nine fungi, grown at 37 °C, were identified as Penicillium chrysogenum, Fusarium sp., and Rhodotorula mucilaginosa. One hundred and three fungi displayed haemolytic activity, 81 produced proteinase, 9 produced phospholipase, and 25 presented dimorphism and a spore diameter ≤ 4 µm. The Antarctic Peninsula region appears to be under the effects of global climate changes, which may expose and accelerate the rock's weathering processes, and expose and release cryptic fungi and other microbes, especially those with innate pathogenic potential, previously arrested in rocks. Consequently, these rocks and their particles may represent a vehicle for the dispersal of microbial propagules, including those able to spread pathogens, along, across, and out of Antarctica.

Cultivable fungi present in Antarctic soils: taxonomy, phylogeny, diversity, and bioprospecting of antiparasitic and herbicidal metabolites

Molecular biology techniques were used to identify 218 fungi from soil samples collected from four islands of Antarctica. These consisted of 22 taxa of 15 different genera belonging to the Zygomycota, Ascomycota, and Basidiomycota. Mortierella, Antarctomyces, Pseudogymnoascus, and Penicillium were the most frequently isolated genera and Penicillium tardochrysogenum, Penicillium verrucosus, Goffeauzyma gilvescens, and Mortierella sp. 2 the most abundant taxa. All fungal isolates were cultivated using solid-state fermentation to obtain their crude extracts. Pseudogymnoascus destructans, Mortierella parvispora, and Penicillium chrysogenum displayed antiparasitic activities, whilst extracts of P. destructans, Mortierella amoeboidea, Mortierella sp. 3, and P. tardochrysogenum showed herbicidal activities. Reported as pathogenic for bats, different isolates of P. destructans exhibited trypanocidal activities and herbicidal activity, and may be a source of bioactive molecules to be considered for chemotherapy against neglected tropical diseases. The abundant presence of P. destructans in soils of the four islands gives evidence supporting that soils in the Antarctic Peninsula constitute a natural source of strains of this genus, including some P. destructans strains that are phylogenetically close to those that infect bats in North America and Europe/Palearctic Asia.

Pathogenic potential of environmental resident fungi from ornithogenic soils of Antarctica

We assessed the diversity of cultivable fungi in the ornithogenic soil nests of bird species like Phalacrocorax atriceps, Macronectes giganteus, Pygoscelis antarcticus, and Pygoscelis papua in the Antarctic islands. From 481 fungi isolated at 15 °C, only 50 displayed growth at 37 °C, and were identified as 14 species of 15 genera. Aspergillus fumigatus, Penicillium chrysogenum, and Rhodotorula mucilaginosa were the most abundant species obtained. Fifty taxa grew at 40 °C; displayed haemolytic and phospholipase activities; produced tiny spores, capsule, and melanin; showed growth at different pH; and showed resistance to amphotericin B. Interestingly, the minimum inhibitory concentration of amphotericin B increased by 5-10 fold for some A. fumigatus isolates after phagocytosis by amoeba. Our results show relations among fungal community compositions present in Antarctic ornithogenic soil and their pathogenic risk to humans in vitro. As the Antarctica Peninsula is a major region of the planet affected by global climate changes, our results, though preliminary, raise concerns about the dispersal of potential pathogenic microbes present in Antarctic substrates by wild birds, which can fly great distances and spread potential pathogens mainly to South America and Oceania.