DNA metabarcoding of fungal diversity in air and snow of Livingston Island, South Shetland Islands, Antarctica

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.

Fungal diversity present in snow sampled in summer in the north-west Antarctic Peninsula and the South Shetland Islands, Maritime Antarctica, assessed using metabarcoding

We assessed the fungal diversity present in snow sampled during summer in the north-west Antarctic Peninsula and the South Shetland Islands, maritime Antarctica using a metabarcoding approach. A total of 586,693 fungal DNA reads were obtained and assigned to 203 amplicon sequence variants (ASVs). The dominant phylum was Ascomycota, followed by Basidiomycota, Mortierellomycota, Chytridiomycota and Mucoromycota. Penicillium sp., Pseudogymnoascus pannorum, Coniochaeta sp., Aspergillus sp., Antarctomyces sp., Phenoliferia sp., Cryolevonia sp., Camptobasidiaceae sp., Rhodotorula mucilaginosa and Bannozyma yamatoana were assessed as abundant taxa. The snow fungal diversity indices were high but varied across the different locations sampled. Of the fungal ASVs detected, only 28 were present all sampling locations. The 116 fungal genera detected in the snow were dominated by saprotrophic taxa, followed by symbiotrophic and pathotrophic. Our data indicate that, despite the low temperature and oligotrophic conditions, snow can host a richer mycobiome than previously reported through traditional culturing studies. The snow mycobiome includes a complex diversity dominated by cosmopolitan, cold-adapted, psychrophilic and endemic taxa. While saprophytes dominate this community, a range of other functional groups are present.

Bioprospecting the potential of the microbial community associated to Antarctic marine sediments for hydrocarbon bioremediation

Microorganisms that inhabit the cold Antarctic environment can produce ligninolytic enzymes potentially useful in bioremediation. Our study focused on characterizing Antarctic bacteria and fungi from marine sediment samples of King George and Deception Islands, maritime Antarctica, potentially affected by hydrocarbon influence, able to produce enzymes for use in bioremediation processes in environments impacted with petroleum derivatives. A total of 168 microorganism isolates were obtained: 56 from sediments of King George Island and 112 from Deception Island. Among them, five bacterial isolates were tolerant to cell growth in the presence of diesel oil and gasoline and seven fungal were able to discolor RBBR dye. In addition, 16 isolates (15 bacterial and one fungal) displayed enzymatic emulsifying activities. Two isolates were characterized taxonomically by showing better biotechnological results. Psychrobacter sp. BAD17 and Cladosporium sp. FAR18 showed pyrene tolerance (cell growth of 0.03 g mL-1 and 0.2 g mL-1) and laccase enzymatic activity (0.006 UL-1 and 0.10 UL-1), respectively. Our results indicate that bacteria and fungi living in sediments under potential effect of hydrocarbon pollution may represent a promising alternative to bioremediate cold environments contaminated with polluting compounds derived from petroleum such as polycyclic aromatic hydrocarbons and dyes.

Study of the Bacterial, Fungal, and Archaeal Communities Structures near the Bulgarian Antarctic Research Base "St. Kliment Ohridski" on Livingston Island, Antarctica

As belonging to one of the most isolated continents on our planet, the microbial composition of different environments in Antarctica could hold a plethora of undiscovered species with the potential for biotechnological applications. This manuscript delineates our discoveries after an expedition to the Bulgarian Antarctic Base "St. Kliment Ohridski" situated on Livingston Island, Antarctica. Amplicon-based metagenomics targeting the 16S rRNA genes and ITS2 region were employed to assess the metagenomes of the bacterial, fungal, and archaeal communities across diverse sites within and proximal to the research station. The predominant bacterial assemblages identified included Oxyphotobacteria, Bacteroidia, Gammaprotobacteria, and Alphaprotobacteria. A substantial proportion of cyanobacteria reads were attributed to a singular uncultured taxon within the family Leptolyngbyaceae. The bacterial profile of a lagoon near the base exhibited indications of penguin activity, characterized by a higher abundance of Clostridia, similar to lithotelm samples from Hannah Pt. Although most fungal reads in the samples could not be identified at the species level, noteworthy genera, namely Betamyces and Tetracladium, were identified. Archaeal abundance was negligible, with prevalent groups including Woesearchaeales, Nitrosarchaeum, Candidatus Nitrosopumilus, and Marine Group II.

Investigating non-fungal eukaryotic diversity in snow in the Antarctic Peninsula region using DNA metabarcoding

Snow is a unique microhabitat, despite being a harsh environment, multiple life forms have adapted to survive in it. While algae, bacteria and fungi are dominant microorganisms in Antarctic snow, little is known about other organisms that may be present in this habitat. We used metabarcoding to investigate DNA sequence diversity of non-fungal eukaryotes present in snow obtained from six different sites across the Maritime Antarctica. A total of 20 taxa were assigned to obtained sequences, representing five Kingdoms (Chromista, Protozoa, Viridiplantae and Metazoa) and four phyla (Ciliophora, Cercozoa, Chlorophyta and Cnidaria). The highest diversity indices were detected in Trinity Peninsula followed by Robert Island, Arctowski Peninsula, Deception Island, King George Island and Snow Island. The most abundant assignments were to Trebouxiophyceae, followed by Chlamydomonas nivalis and Chlamidomonadales. No taxa were detected at all sites. Three potentially new records for Antarctica were detected: two Ciliophora (Aspidisca magna and Stokesia sp.) and the green algae Trebouxia potteri. Our data suggested that similarities found between the sites may be more related with snow physicochemical properties rather than geographic proximity or latitude. This study provides new insights into the diversity and distribution of eukaryotic organisms in Antarctic snow.

Lichen-associated microbial members are prevalent in the snow microbiome of a sub-arctic alpine tundra

Snow is the largest component of the cryosphere, with its cover and distribution rapidly decreasing over the last decade due to climate warming. It is imperative to characterize the snow (nival) microbial communities to better understand the role of microorganisms inhabiting these rapidly changing environments. Here, we investigated the core nival microbiome, the cultivable microbial members, and the microbial functional diversity of the remote Uapishka mountain range, a massif of alpine sub-arctic tundra and boreal forest. Snow samples were taken over a two-month interval along an altitude gradient with varying degree of anthropogenic traffic and vegetation cover. The core snow alpine tundra/boreal microbiome, which was present across all samples, constituted of Acetobacterales, Rhizobiales and Acidobacteriales bacterial orders, and of Mycosphaerellales and Lecanorales fungal orders, with the dominant fungal taxa being associated with lichens. The snow samples had low active functional diversity, with Richness values ranging from 0 to 19.5. The culture-based viable microbial enumeration ranged from 0 to 8.05 × 103 CFUs/mL. We isolated and whole-genome sequenced five microorganisms which included three fungi, one alga, and one potentially novel bacterium of the Lichenihabitans genus; all of which appear to be part of lichen-associated taxonomic clades.

A Deep Insight into the Diversity of Microfungal Communities in Arctic and Antarctic Lakes

We assessed fungal diversity in water and sediment samples obtained from five Arctic lakes in Ny-Ålesund (Svalbard Islands, High Arctic) and five Antarctic lakes on Livingston and Deception Islands (South Shetland Islands), using DNA metabarcoding. A total of 1,639,074 fungal DNA reads were detected and assigned to 5980 ASVs amplicon sequence variants (ASVs), with only 102 (1.7%) that were shared between the two Polar regions. For Arctic lakes, unknown fungal taxa dominated the sequence assemblages, suggesting the dominance of possibly undescribed fungi. The phylum Chytridiomycota was the most represented in the majority of Arctic and Antarctic samples, followed by Rozellomycota, Ascomycota, Basidiomycota, and the less frequent Monoblepharomycota, Aphelidiomycota, Mortierellomycota, Mucoromycota, and Neocallimastigomycota. At the genus level, the most abundant genera included psychrotolerant and cosmopolitan cold-adapted fungi including Alternaria, Cladosporium, Cadophora, Ulvella (Ascomycota), Leucosporidium, Vishniacozyma (Basidiomycota), and Betamyces (Chytridiomycota). The assemblages displayed high diversity and richness. The assigned diversity was composed mainly of taxa recognized as saprophytic fungi, followed by pathogenic and symbiotic fungi.

Comparison of Atmospheric and Lithospheric Culturable Bacterial Communities from Two Dissimilar Active Volcanic Sites, Surtsey Island and Fimmvörðuháls Mountain in Iceland

Surface microbes are aerosolized into the atmosphere by wind and events such as dust storms and volcanic eruptions. Before they reach their deposition site, they experience stressful atmospheric conditions which preclude the successful dispersal of a large fraction of cells. In this study, our objectives were to assess and compare the atmospheric and lithospheric bacterial cultivable diversity of two geographically different Icelandic volcanic sites: the island Surtsey and the Fimmvörðuháls mountain, to predict the origin of the culturable microbes from these sites, and to select airborne candidates for further investigation. Using a combination of MALDI Biotyper analysis and partial 16S rRNA gene sequencing, a total of 1162 strains were identified, belonging to 72 species affiliated to 40 genera with potentially 26 new species. The most prevalent phyla identified were Proteobacteria and Actinobacteria. Statistical analysis showed significant differences between atmospheric and lithospheric microbial communities, with distinct communities in Surtsey’s air. By combining the air mass back trajectories and the analysis of the closest representative species of our isolates, we concluded that 85% of our isolates came from the surrounding environments and only 15% from long distances. The taxonomic proportions of the isolates were reflected by the site’s nature and location.

Cryptic fungal diversity revealed by DNA metabarcoding in historic wooden structures at Whalers Bay, Deception Island, maritime Antarctic

We provide the first assessment of fungal diversity associated with historic wooden structures at Whalers Bay (Heritage Monument 71), Deception Island, maritime Antarctic, using DNA metabarcoding. We detected a total of 177 fungal amplicon sequence variants (ASVs) dominated by the phyla Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota, Monoblepharomycota, Rozellomycota, and Zoopagomycota. The assemblages were dominated by Helotiales sp. 1 and Herpotrichiellaceae sp. 1. Functional assignments indicated that the taxa detected were dominated by saprotrophic, plant and animal pathogenic, and symbiotic taxa. Metabarcoding revealed the presence of a rich and complex fungal community, which may be due to the wooden structures acting as baits attracting taxa to niches sheltered against extreme conditions, generating a hotspot for fungi in Antarctica. The sequences assigned included both cosmopolitan and endemic taxa, as well as potentially unreported diversity. The detection of DNA assigned to taxa of human and animal opportunistic pathogens raises a potential concern as Whalers Bay is one of the most popular visitor sites in Antarctica. The use of metabarcoding to detect DNA present in environmental samples does not confirm the presence of viable or metabolically active fungi and further studies using different culturing conditions and media, different growth temperatures and incubation periods, in combination with further molecular approaches such as shotgun sequencing are now required to clarify the functional ecology of these fungi.

Soil Fungal Diversity and Ecology Assessed Using DNA Metabarcoding along a Deglaciated Chronosequence at Clearwater Mesa, James Ross Island, Antarctic Peninsula

We studied the fungal diversity present in soils sampled along a deglaciated chronosequence from para- to periglacial conditions on James Ross Island, north-east Antarctic Peninsula, using DNA metabarcoding. A total of 88 amplicon sequence variants (ASVs) were detected, dominated by the phyla Ascomycota, Basidiomycota and Mortierellomycota. The uncommon phyla Chytridiomycota, Rozellomycota, Monoblepharomycota, Zoopagomycota and Basidiobolomycota were detected. Unknown fungi identified at higher hierarchical taxonomic levels (Fungal sp. 1, Fungal sp. 2, Spizellomycetales sp. and Rozellomycotina sp.) and taxa identified at generic and specific levels (Mortierella sp., Pseudogymnoascus sp., Mortierella alpina, M. turficola, Neoascochyta paspali, Penicillium sp. and Betamyces sp.) dominated the assemblages. In general, the assemblages displayed high diversity and richness, and moderate dominance. Only 12 of the fungal ASVs were detected in all chronosequence soils sampled. Sequences representing saprophytic, pathogenic and symbiotic fungi were detected. Based on the sequence diversity obtained, Clearwater Mesa soils contain a complex fungal community, including the presence of fungal groups generally considered rare in Antarctica, with dominant taxa recognized as cold-adapted cosmopolitan, endemic, saprotrophic and phytopathogenic fungi. Clearwater Mesa ecosystems are impacted by the effects of regional climatic changes, and may provide a natural observatory to understand climate change effects over time.

Microbial Community Composition of the Antarctic Ecosystems: Review of the Bacteria, Fungi, and Archaea Identified through an NGS-Based Metagenomics Approach

Antarctica represents a unique environment, both due to the extreme meteorological and geological conditions that govern it and the relative isolation from human influences that have kept its environment largely undisturbed. However, recent trends in climate change dictate an unavoidable change in the global biodiversity as a whole, and pristine environments, such as Antarctica, allow us to study and monitor more closely the effects of the human impact. Additionally, due to its inaccessibility, Antarctica contains a plethora of yet uncultured and unidentified microorganisms with great potential for useful biological activities and production of metabolites, such as novel antibiotics, proteins, pigments, etc. In recent years, amplicon-based next-generation sequencing (NGS) has allowed for a fast and thorough examination of microbial communities to accelerate the efforts of unknown species identification. For these reasons, in this review, we present an overview of the archaea, bacteria, and fungi present on the Antarctic continent and the surrounding area (maritime Antarctica, sub-Antarctica, Southern Sea, etc.) that have recently been identified using amplicon-based NGS methods.

Fungal diversity in a sediment core from climate change impacted Boeckella Lake, Hope Bay, north-eastern Antarctic Peninsula assessed using metabarcoding

We studied the fungal DNA present in a lake sediment core obtained from Trinity Peninsula, Hope Bay, north-eastern Antarctic Peninsula, using metabarcoding through high-throughput sequencing (HTS). Sequences obtained were assigned to 146 amplicon sequence variants (ASVs) primarily representing unknown fungi, followed by the phyla Ascomycota, Rozellomycota, Basidiomycota, Chytridiomycota and Mortierellomycota. The most abundant taxa were assigned to Fungal sp., Pseudeurotium hygrophilum, Rozellomycota sp. 1, Pseudeurotiaceae sp. 1 and Chytridiomycota sp. 1. The majority of the DNA reads, representing 40 ASVs, could only be assigned at higher taxonomic levels and may represent taxa not currently included in the sequence databases consulted and/or be previously undescribed fungi. Different sections of the core were characterized by high sequence diversity, richness and moderate ecological dominance indices. The assigned diversity was dominated by cosmopolitan cold-adapted fungi, including known saprotrophic, plant and animal pathogenic and symbiotic taxa. Despite the overall dominance of Ascomycota and Basidiomycota and psychrophilic Mortierellomycota, members of the cryptic phyla Rozellomycota and Chytridiomycota were also detected in abundance. As Boeckella Lake may cease to exist in approaching decades due the effects of local climatic changes, it also an important location for the study of the impacts of these changes on Antarctic microbial diversity.

Fungi in the Antarctic Cryosphere: Using DNA Metabarcoding to Reveal Fungal Diversity in Glacial Ice from the Antarctic Peninsula Region

We assessed fungal diversity present in glacial from the Antarctic Peninsula using DNA metabarcoding through high-throughput sequencing (HTS). We detected a total of 353,879 fungal DNA reads, representing 94 genera and 184 taxa, in glacial ice fragments obtained from seven sites in the north-west Antarctic Peninsula and South Shetland Islands. The phylum Ascomycota dominated the sequence diversity, followed by Basidiomycota and Mortierellomycota. Penicillium sp., Cladosporium sp., Penicillium atrovenetum, Epicoccum nigrum, Pseudogymnoascus sp. 1, Pseudogymnoascus sp. 2, Phaeosphaeriaceae sp. and Xylaria grammica were the most dominant taxa, respectively. However, the majority of the fungal diversity comprised taxa of rare and intermediate relative abundance, predominately known mesophilic fungi. High indices of diversity and richness were calculated, along with moderate index of dominance, which varied among the different sampling sites. Only 26 (14%) of the total fungal taxa detected were present at all sampling sites. The identified diversity was dominated by saprophytic taxa, followed by known plant and animal pathogens and a low number of symbiotic fungi. Our data suggest that Antarctic glacial ice may represent a hotspot of previously unreported fungal diversity; however, further studies are required to integrate HTS and culture approaches to confirm viability of the taxa detected.

Molecular-Based Diversity Studies and Field Surveys Are Not Mutually Exclusive: On the Importance of Integrated Methodologies in Mycological Research

Understanding and describing the diversity of living organisms is a great challenge. Fungi have for a long time been, and unfortunately still are, underestimated when it comes to taxonomic research. The foundations were laid by the first mycologists through field observations. These important fundamental works have been and remain vital reference works. Nevertheless, a non-negligible part of the studied funga escaped their attention. Thanks to modern developments in molecular techniques, the study of fungal diversity has been revolutionized in terms of tools and knowledge. Despite a number of disadvantages inherent to these techniques, traditional field-based inventory work has been increasingly superseded and neglected. This perspective aims to demonstrate the central importance of field-based research in fungal diversity studies, and encourages researchers not to be blinded by the sole use of molecular methods.

Environmental DNA reveals diversity and abundance of Alternaria species in neighbouring heterogeneous landscapes in Worcester, UK

Alternaria is a pathogenic and allergenic fungus affecting 400 plant species and 334 million people globally. This study aimed at assessing the diversity of Alternaria species in airborne samples collected from closely located (7 km apart) and heterogeneous sites (rural, urban and unmanaged grassland) in Worcester and Lakeside, the UK. A secondary objective was to examine how the ITS1 subregion varies from ITS2 in Alternaria species diversity and composition. Airborne spores were collected using Burkard 7-day and multi-vial Cyclone samplers for the period 5 July 2016-9 October 2019. Air samples from the Cyclone were amplified using the ITS1and ITS2 subregions and sequenced using Illumina MiSeq platform whereas those from the Burkard sampler were identified and quantified using optical microscopy. Optical microscopy and eDNA revealed a high abundance of Alternaria in the rural, urban and unmanaged sites. ITS1 and ITS2 detected five and seven different Alternaria species at the three sampling sites, respectively. A. dactylidicola, A. metachromatica and A. infectoria were the most abundant. The rural, urban and unmanaged grassland sites had similar diversity (PERMANOVA) of the species due to similarity in land use and proximity of the sites. Overall, the study showed that heterogeneous and neighbouring sites with similar land uses can have similar Alternaria species. It also demonstrated that an eDNA approach can complement the classical optical microscopy method in providing more precise information on fungal species diversity in an environment for targeted management. Similar studies can be replicated for other allergenic and pathogenic fungi.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10453-022-09760-9.

Description of the First Four Species of the Genus Pseudogymnoascus From Antarctica

The genus Pseudogymnoascus represents a diverse group of fungi widely distributed in different cold regions on Earth. Our current knowledge of the species of Pseudogymnoascus is still very limited. Currently, there are only 15 accepted species of Pseudogymnoascus that have been isolated from different environments in the Northern Hemisphere. In contrast, species of Pseudogymnoascus from the Southern Hemisphere have not yet been described. In this work, we characterized four fungal strains obtained from Antarctic marine sponges. Based on multilocus phylogenetic analyses and morphological characterizations we determined that these strains are new species, for which the names Pseudogymnoascus antarcticus sp. nov., Pseudogymnoascus australis sp. nov., Pseudogymnoascus griseus sp. nov., and Pseudogymnoascus lanuginosus sp. nov. are proposed. Phylogenetic analyses indicate that the new species form distinct lineages separated from other species of Pseudogymnoascus with strong support. The new species do not form sexual structures and differ from the currently known species mainly in the shape and size of their conidia, the presence of chains of arthroconidia, and the appearance of their colonies. This is the first report of new species of Pseudogymnoascus not only from Antarctica but also from the Southern Hemisphere.

Highly differentiated soil bacterial communities in Victoria Land macro-areas (Antarctica)

Ice-free areas of Victoria Land, in Antarctica, are characterized by different terrestrial ecosystems, that are dominated by microorganisms supporting highly adapted communities. Despite the unique conditions of these ecosystems, reports on their bacterial diversity are still fragmentary. From this perspective, 60 samples from 14 localities were analyzed. These localities were distributed in coastal sites with differently developed biological soil crusts, inner sites in the McMurdo Dry Valleys with soils lacking of plant coverage, and a site called Icarus Camp, with a crust developed on a thin locally weathered substrate of the underlying parent granitic-rock. Bacterial diversity was studied through 16S rRNA metabarcoding sequencing. Communities diversity, composition and the abundance and composition of different taxonomic groups were correlated to soil physicochemical characteristics. Firmicutes, Bacteroidetes, Cyanobacteria and Proteobacteria dominated these communities. Most phyla were mainly driven by soil granulometry, an often disregarded parameter and other abiotic parameters. Bacterial composition differed greatly among the three macrohabitats, each having a distinct bacterial profile. Communities within the two main habitats (coastal and inner ones) were well differentiated from each other as well, therefore depending on site-specific physicochemical characteristics. A core community of the whole samples was observed, mainly represented by Firmicutes and Bacteroidetes.

Fungi Present in Antarctic Deep-Sea Sediments Assessed Using DNA Metabarcoding

We assessed fungal diversity in deep-sea sediments obtained from different depths in the Southern Ocean using the internal transcribed spacer 2 (ITS2) region of nuclear ribosomal DNA by metabarcoding through high-throughput sequencing (HTS). We detected 655,991 DNA reads representing 263 fungal amplicon sequence variants (ASVs), dominated by Ascomycota, Basidiomycota, Mortierellomycota, Mucoromycota, Chytridiomycota and Rozellomycota, confirming that deep-sea sediments can represent a hotspot of fungal diversity in Antarctica. The community diversity detected included 17 dominant fungal ASVs, 62 intermediate and 213 rare. The dominant fungi included taxa of Mortierella, Penicillium, Cladosporium, Pseudogymnoascus, Phaeosphaeria and Torula. Despite the extreme conditions of the Southern Ocean benthos, the total fungal community detected in these marine sediments displayed high indices of diversity and richness, and moderate dominance, which varied between the different depths sampled. The highest diversity indices were obtained in sediments from 550 m and 250 m depths. Only 49 ASVs (18.63%) were detected at all the depths sampled, while 16 ASVs were detected only in the deepest sediment sampled at 1463 m. Based on sequence identities, the fungal community included some globally distributed taxa, primarily recorded otherwise from terrestrial environments, suggesting transport from these to deep marine sediments. The assigned taxa included symbionts, decomposers and plant-, animal- and human-pathogenic fungi, suggesting that deep-sea sediments host a complex fungal diversity, although metabarcoding does not itself confirm that living or viable organisms are present.

DNA Metabarcoding to Assess the Diversity of Airborne Fungi Present over Keller Peninsula, King George Island, Antarctica

We assessed fungal diversity present in air samples obtained from King George Island, Antarctica, using DNA metabarcoding through high-throughput sequencing. We detected 186 fungal amplicon sequence variants (ASVs) dominated by the phyla Ascomycota, Basidiomycota, Mortierellomycota, Mucoromycota, and Chytridiomycota. Fungi sp. 1, Agaricomycetes sp. 1, Mortierella parvispora, Mortierella sp. 2, Penicillium sp., Pseudogymnoascus roseus, Microdochium lycopodinum, Mortierella gamsii, Arrhenia sp., Cladosporium sp., Mortierella fimbricystis, Moniliella pollinis, Omphalina sp., Mortierella antarctica, and Pseudogymnoascus appendiculatus were the most dominant ASVs. In addition, several ASVs could only be identified at higher taxonomic levels and may represent previously unknown fungi and/or new records for Antarctica. The fungi detected in the air displayed high indices of diversity, richness, and dominance. The airborne fungal diversity included saprophytic, mutualistic, and plant and animal opportunistic pathogenic taxa. The diversity of taxa detected reinforces the hypothesis that the Antarctic airspora includes fungal propagules of both intra- and inter-continental origin. If regional Antarctic environmental conditions ameliorate further in concert with climate warming, these fungi might be able to reactivate and colonize different Antarctic ecosystems, with as yet unknown consequences for ecosystem function in Antarctica. Further aeromycological studies are necessary to understand how and from where these fungi arrive and move within Antarctica and if environmental changes will encourage the development of non-native fungal species in Antarctica.

The largest moss carpet transplant in Antarctica and its bryosphere cryptic biodiversity

As part of the reconstruction of the Brazilian Antarctic Station on King George Island, three areas of moss carpet were transplanted to minimize the impact of the new facilities on the local biodiversity. A total of 650 m² of moss carpet was transplanted to neighboring but previously uncolonized locations and has subsequently survived for the last 3 years. Antarctic moss carpets typically comprise low moss species diversity and are often monospecific. We investigated the cryptic biodiversity that was transplanted along with the carpets using a metabarcoding approach through high throughput sequencing. We targeted 16S rRNA for Bacteria and Archaea, ITS for Fungi and Viridiplantae and Cox1 for Metazoa. We detected DNA representing 263 taxa from five Kingdoms (Chromista, Fungi, Metazoa, Protista and Viridiplantae), two Domains (Archaea and Bacteria) and 33 Phyla associated with the carpet. This diversity included one Archaea, 189 Bacteria, 24 Chromista, 19 Fungi, eight Metazoa, seven Protista and 16 Viridiplantae. Bacteria was the most abundant, rich and diverse group, with Chromista second in diversity and richness. Metazoa was less diverse but second highest in dominance. This is the first study to attempt transplanting a significant area of moss carpet to minimize anthropogenic environmental damage in Antarctica and to use metabarcoding as a proxy to assess diversity associated with Antarctic moss carpets, further highlighting the importance of such habitats for other organisms and their importance for conservation.

Diversity of fungal DNA in lake sediments on Vega Island, north-east Antarctic Peninsula assessed using DNA metabarcoding

We assessed the diversity of fungal DNA present in sediments of three lakes on Vega Island, north-east Antarctic Peninsula using metabarcoding through high-throughput sequencing (HTS). A total of 640,902 fungal DNA reads were detected, which were assigned to 224 taxa of the phyla Ascomycota, Rozellomycota, Basidiomycota, Chytridiomycota and Mortierellomycota, in rank order of abundance. The most abundant genera were Pseudogymnoascus, Penicillium and Mortierella. However, a majority (423,508, 66%) of the reads, representing by 43 ASVs, could only be assigned at higher taxonomic levels and may represent taxa not currently included in the sequence databases used or be new or previously unreported taxa present in Antarctic lakes. The three lakes were characterized by high sequence diversity, richness, and moderate dominance indices. The ASVs were dominated by psychrotolerant and cosmopolitan cold-adapted Ascomycota, Basidiomycota and Mortierellomycota commonly reported in Antarctic environments. However, other taxa detected included unidentified members of Rozellomycota and Chytridiomycota species not previously reported in Antarctic lakes. The assigned diversity was composed mainly of taxa recognized as decomposers and pathogens of plants and invertebrates.

Assessment of fungal diversity present in lakes of Maritime Antarctica using DNA metabarcoding: a temporal microcosm experiment

We evaluated the fungal diversity in two lakes on the South Shetland Islands, using DNA metabarcoding through high-throughput sequencing (HTS). A microcosm experiment was deployed for two consecutive years in lakes on Deception and King George islands to capture potential decomposer freshwater fungi. Analyses of the baits revealed 258,326 DNA reads distributed in 34 fungal taxa of the phyla Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota and Rozellomycota. Tetracladium marchalianum, Tetracladium sp., Rozellomycota sp., Fungal sp. 1 and Fungal sp. 2 were the most common taxa detected. However, the majority of the communities comprised intermediate and rare taxa. Both fungal communities displayed moderate indices of diversity, richness and dominance. Only six taxa were detected in both lakes, including the most dominant T. marchalianum and Tetracladium sp. The high numbers of reads of the known aquatic saprotrophic hyphomycetes T. marchalianum and Tetracladium sp. in the baits suggest that these fungi may digest organic material in Antarctic lakes, releasing available carbon and nutrients to the other aquatic organisms present in the complex lake food web. Our data confirm that the use of cotton baits together with HTS approaches can be appropriate to study the diversity of resident freshwater fungi present in Antarctic lakes.