Diversity and distribution of hidden cultivable fungi associated with marine animals of Antarctica

In the present study, we surveyed the distribution and diversity of fungal assemblages associated with 10 species of marine animals from Antarctica. The collections yielded 83 taxa from 27 distinct genera, which were identified using molecular biology methods. The most abundant taxa were Cladosporium sp. 1, Debaryomyces hansenii, Glaciozyma martinii, Metschnikowia australis, Pseudogymnoascus destructans, Thelebolus cf. globosus, Pseudogymnoascus pannorum, Tolypocladium tundrense, Metschnikowia australis, and different Penicillium species. The diversity, richness, and dominance of fungal assemblages ranged among the host; however, in general, the fungal community, which was composed of endemic and cold-adapted cosmopolitan taxa distributed across the different sites of Antarctic Peninsula, displayed high diversity, richness, and dominance indices. Our results contribute to knowledge about fungal diversity in the marine environment across the Antarctic Peninsula and their phylogenetic relationships with species that occur in other cold, temperate, and tropical regions of the World. Additionally, despite their extreme habitats, marine Antarctic animals shelter cryptic and complex fungal assemblages represented by endemic and cosmopolitan cold-adapted taxa, which may represent interesting models to study different symbiotic associations between fungi and their animal hosts in the extreme conditions of Antarctica.     

Diversity and bioprospecting of fungal communities associated with endemic and cold-adapted macroalgae in Antarctica

We surveyed the distribution and diversity of fungi associated with eight macroalgae from Antarctica and their capability to produce bioactive compounds. The collections yielded 148 fungal isolates, which were identified using molecular methods as belonging to 21 genera and 50 taxa. The most frequent taxa were Geomyces species (sp.), Penicillium sp. and Metschnikowia australis. Seven fungal isolates associated with the endemic Antarctic macroalgae Monostroma hariotii (Chlorophyte) displayed high internal transcribed spacer sequences similarities with the psychrophilic pathogenic fungus Geomyces destructans. Thirty-three fungal singletons (66%) were identified, representing rare components of the fungal communities. The fungal communities displayed high diversity, richness and dominance indices; however, rarefaction curves indicated that not all of the fungal diversity present was recovered. Penicillium sp. UFMGCB 6034 and Penicillium sp. UFMGCB 6120, recovered from the endemic species Palmaria decipiens (Rhodophyte) and M. hariotii, respectively, yielded extracts with high and selective antifungal and/or trypanocidal activities, in which a preliminary spectral analysis using proton nuclear magnetic resonance spectroscopy indicated the presence of highly functionalised aromatic compounds. These results suggest that the endemic and cold-adapted macroalgae of Antarctica shelter a rich, diversity and complex fungal communities consisting of a few dominant indigenous or mesophilic cold-adapted species, and a large number of rare and/or endemic taxa, which may provide an interesting model of algal–fungal interactions under extreme conditions as well as a potential source of bioactive compounds.     

Diversity and bioprospecting of cultivable fungal assemblages in sediments of lakes in the Antarctic Peninsula

We recovered 195 fungal isolates from the sediments of different lakes in the Antarctic Peninsula, which were screened to detect bioactive compounds. Forty-two taxa belonging to the phyla Ascomycota, Basidiomycota, and Mortierellomycota were identified. Thelebolus globosus, Antarctomyces psychrotrophicus, Pseudogymnoascus verrucosus, Vishniacozyma victoriae, and Phenoliferia sp. were found to be the most prevalent. The fungal assemblages showed high diversity and richness, but low dominance values. However, the diversity indices and fungal distribution ranged according to the different lake sediments. Sixty fungal extracts displayed at least one biological activity against the evaluated targets. Among them, Pseudogymnoascus destructans showed selective trypanocidal activity, Cladosporium sp. 1 and Trichoderma polysporum showed antifungal activity, and Pseudogymnoascus appendiculatus and Helotiales sp. showed high herbicidal activity. We detected a rich and diverse fungal community composed of cold cosmopolitan and psychrophilic endemic taxa recognized as decomposers, symbiotics, pathogens, and potential new species, in the sediments of Antarctic lakes. The dynamics and balance of this fungal community represents an interesting aquatic web model for further ecological and evolutionary studies under extreme conditions and potential climate changes in the regions. In addition, we detected fungal taxa and isolates able to produce bioactive compounds that may represent the source of prototype molecules for applications in medicine and agriculture.     

Diversity and ecology of fungal assemblages present in lake sediments at Clearwater Mesa,James Ross Island,Antarctica, assessed using metabarcoding of environmental DNA

We detected the fungal assemblages present in lake sediments on James Ross Island, Antarctica, using DNA metabarcoding. A total of 132 amplicon sequence variants (ASVs) were assigned, dominated by taxa of the phyla Ascomycota, Basidiomycota, Mortierellomycota and Mucoromycota. The less common phyla Chytridiomycota, Rozellomycota, Monoblepharomycota, Basidiobolomycota, Aphelidiomycota and the fungus-like Straminopila were also detected. Fungal sp. 1, Fungal sp. 2, Spizellomycetales sp. 1, Rozellomycotina sp. 1, Talaromyces rubicundus and Betamyces sp. dominated the assemblages. In general, the assemblages displayed high diversity and richness, and moderate dominance. Saprophytic, pathogenic and symbiotic fungi were detected. The metabarcoding data indicated that Antarctic lakes may represent a hotspot of fungal diversity in Antarctica. The sediments of these lakes may accumulate different fungal fragments and active fungal mycelia and their propagules, deposited over long periods of time. Lakes in the Antarctic Peninsula region are sensitive environments threatened by the effects of regional climatic changes. The abundance of sequences of little-known Rozellomycota and Chytridiomycota (Spizellomycetales) taxa in these ecosystems highlights the need for further studies to identify if they are metabolically active in the sediments and whether they have potentially pathogenic capabilities.     

Comparison of root-associated communities of native and non-native ectomycorrhizal hosts in an urban landscape

Non-native tree species are often used as ornamentals in urban landscapes. However, their root-associated fungal communities remain yet to be examined in detail. Here, we compared richness, diversity and community composition of ectomycorrhizosphere fungi in general and ectomycorrhizal (EcM) fungi in particular between a non-native Pinus nigra and a native Quercus macrocarpa across a growing season in urban parks using 454-pyrosequencing. Our data show that, while the ectomycorrhizosphere community richness and diversity did not differ between the two host, the EcM communities associated with the native host were often more species rich and included more exclusive members than those of the non-native hosts. In contrast, the ectomycorrhizosphere communities of the two hosts were compositionally clearly distinct in nonmetric multidimensional ordination analyses, whereas the EcM communities were only marginally so. Taken together, our data suggest EcM communities with broad host compatibilities and with a limited numbers of taxa with preference to the non-native host. Furthermore, many common fungi in the non-native Pinus were not EcM taxa, suggesting that the fungal communities of the non-native host may be enriched in non-mycorrhizal fungi at the cost of the EcM taxa. Finally, while our colonization estimates did not suggest a shortage in EcM inoculum for either host in urban parks, the differences in the fungi associated with the two hosts emphasize the importance of using native hosts in urban environments as a tool to conserve endemic fungal diversity and richness in man-made systems.     

Non-lichenized Antarctic fungi: transient visitors or members of a cryptic ecosystem?

To date over 1 000 non-lichenized fungal species have been recorded by collection or isolation from Antarctica, and additional taxa are now being identified by molecular studies. The number and variety of species recorded so far suggest that the fungi may be the most diverse biota in the Antarctic, and the additional taxa identified by molecular surveys suggest that the true diversity may be far greater than is currently estimated. Fungi occupy many different ecological niches in the Antarctic, and their significance in these niches is only poorly understood. The majority of species described from the region have been identified as members of broadly cosmopolitan groups, but there is some evidence for both endemic strains and populations. This review brings together the current broad systematic and ecological findings for the non-lichenized Antarctic fungi.     

Penicillium solitum: a mesophilic, psychrotolerant fungus present in marine sediments from Antarctica

Few studies have addressed the diversity of cultivable fungi from marine sediments, especially those from Antarctica. In the present study, we evaluated the presence and distribution of cultivable fungi in marine core sediments obtained from 100, 500, 700 and 1,100 m below the Antarctic Ocean surface. Fifty-two fungal isolates were identified as Penicillium solitum by their physiological and morphological characteristics, and the identity of 12 representative isolates was further confirmed by sequencing of the ITS1-5.8S-ITS2 and β-tubulin genes. P. solitum displayed high sequence similarity to Penicillium taxa that have been described from other marine habitats. Conidial germination of P. solitum occurred at low temperatures and high salinities. In addition, P. solitum displayed extracellular amylasic and esterasic activities. The isolation of P. solitum from marine sediments in Antarctica and its survival at low temperatures and high salt concentrations suggest that it is adapted to the cold and halophilic environment of the Antarctic oceans. Because P. solitum produces extracellular enzymes, it is an interesting eukaryotic model for the study of structure–function relationships during enzymatic biocatalysis and biotransformation under extreme conditions. Marine sediments from Antarctica may represent a unique source for obtaining extremophilic fungi. New studies using different culture media, temperatures ranges and pressure conditions as well as metagenomic techniques can assist in understanding the extremophilic fungal communities in marine sediments across the Antarctic Ocean.     

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.

     

The diversity, antimicrobial and anticancer activity of endophytic fungi associated with the medicinal plant Stryphnodendron adstringens (Mart.) Coville (Fabaceae) from the Brazilian savannah

The diversity and biological activities of the endophytic fungi associated with the Brazilian medicinal plant Stryphnodendron adstringens were studied. A total of 320 fungal isolates were obtained, and 66 phylotypes comprising 25 genera were identified. The fungal community of S. adstringens displayed high richness, diversity and low dominance indices. The most abundant phylotypes were closely related to Diaporthe phaseolorum, Guignardia camelliae, and Preussia pseudominima. Sixteen fungal extracts displayed biological activities when screened against bacteria, fungi, cancer cell lines, and amastigote forms of Leishmania amazonensis. The extract of phylotype Nigrospora cf. oryzae exhibited a selective antifungal activity and inhibited the growth of Candida albicans and Cladosporium sphaerospermum. The extracts of Diaporthe cf. phaseolorum and Xylaria sp. phylotypes displayed anticancer activities. Our results indicate that the endophytes associate with this medicinal plant may be a source for novel drugs.     

Plant species richness and productivity determine the diversity of soil fungal guilds in temperate coniferous forest and bog habitats

Fungi have important roles as decomposers, mycorrhizal root symbionts and pathogens in forest ecosystems, but there is limited information about their diversity and composition at the landscape scale. This work aimed to disentangle the factors underlying fungal richness and composition along the landscape‐scale moisture, organic matter and productivity gradients. Using high‐throughput sequencing, we identified soil fungi from 54 low‐productivity Pinus sylvestris‐dominated plots across three study areas in Estonia and determined the main predictors of fungal richness based on edaphic, floristic and spatial variables. Fungal richness displayed unimodal relationship with organic matter and deduced soil moisture. Plant richness and productivity constituted the key predictors for taxonomic richness of functional guilds. Composition of fungi and the main ectomycorrhizal fungal lineages and hyphal exploration types was segregated by moisture availability and soil nitrogen. We conclude that plant productivity and diversity determine the richness and proportion of most functional groups of soil fungi in low‐productive pine forests on a landscape scale. Adjacent stands of pine forest may differ greatly in the dominance of functional guilds that have marked effects on soil carbon and nitrogen cycling in these forest ecosystems.     

Diversity and community structure of ectomycorrhizal fungi in a wooded meadow

Wooded meadows are seminatural plant communities that support high diversity of various taxa. Due to changes in land use, wooded meadows have severely declined during the last century. The dominant trees in wooded meadows acquire mineral nutrients via ectomycorrhizal fungi. Using anatomotyping and sequencing of root tips, interpolation and extrapolation methods, we studied the diversity and community structure of ectomycorrhizal fungi in two soil horizons of both managed and forested parts of a wooded meadow in Estonia. Species of Thelephoraceae, Sebacinaceae and the genus Inocybe dominated the whole ectomycorrhizal fungal community of 172 observed species. Forested and managed parts of the wooded meadow harboured different communities of ectomycorrhizal fungi, whereas soil horizon had a negligible effect on the fungal community composition. Diverse soil conditions and host trees likely support the high richness of ectomycorrhizal fungi in the wooded meadow ecosystem. Direct sequencing integrated with interpolation and extrapolation methods are promising to identify the fungi at the species level and to compare species richness between communities of ectomycorrhizal fungi.     

Geographic and Tissue Influences on Endophytic Fungal Communities of Taxus chinensis var. mairei in China

Endophytc fungi were collected from the barks, branches and leaves of Taxus chinensis var. mairei from the Jiangxi, Zhejiang and Chongqing regions of China and their influences on geographic and tissue investigated. A total of 145 fungal taxa were identified based on molecular techniques, of these 125 taxa (86.2 %) belonging to Ascomycota, 14 (9.7 %) to Basidiomycota, 5 (3.4 %) to Zygomycota, and 1 (0.7 %) to undefined fungi. The species richness and diversity of endophytic fungi were significantly affected by tissue, and were 1.2–2.5-fold higher in the branches and barks when compared to the leaves. The locality affected the species richness per tree and the shannon diversity index per tree by longitude. The endophyte assemblages were strongly shaped by locality and tissue according to partial least squares discriminant analysis. In addition, the distributions of dominant fungi at orders and genera levels differed as a function of locality and tissue. Most of the dominant taxa showed spatial heterogeneity and tissue specificity or preference and many fungal taxa with low frequency were special to one locality or one tissue.     

Ectomycorrhizal fungal communities of pedunculate and sessile oak seedlings from bare-root forest nurseries

In this study, we present the detailed molecular investigation of the ectomycorrhizal (ECM) community of Quercus petraea and Quercus robur seedlings grown in bare-root forest nurseries. In all tested oak samples, mycorrhizal colonization was nearly 100%. Morphological observation and molecular investigations (sequencing of fungal ITS rDNA) revealed a total of 23 mycorrhizal taxa. The most frequent and abundant fungal taxa were Hebeloma sacchariolens, Tuber sp., and Peziza sp.; from the detected fungal taxa, 20 were noted for Q. petraea and 23 for Q. robur. Depending on the nursery, the species richness of identified ECM fungal taxa for both oak species ranged from six to 11 taxa. The mean species richness for all nurseries was 5.36 and 5.82 taxa per Q. petraea and Q. robur sample, respectively. According to the analysis of similarity, ECM fungal communities were similar for Q. petraea and Q. robur (R = 0.019; p = 0.151). On the other hand, detected fungal communities were significantly different between nurseries (R = 0.927; p < 0.0001). Using the Spearman rank correlation, it was determined that the ectomycorrhizal diversity (in terms of richness, the Shannon diversity, evenness, and Simpson dominance indices) is significantly related to the soil parameters of each nursery. We conclude that individual nursery may be considered as separate ecological niches that strongly discriminate diversity of ECM fungi.     

Endophytic and mycorrhizal fungi associated with roots of endangered native orchids from the Atlantic Forest, Brazil

The composition and diversity of fungal communities associated with three endangered orchid species, Hadrolaelia jongheana, Hoffmannseggella caulescens, and Hoffmannseggella cinnabarina, found in different vegetation formations of the Atlantic Forest were determined by constructing clone libraries and by applying diversity and richness indices. Our results demonstrated the presence of Basidiomycetes. Sebacinales (81.61 %) and Cantharellales (12.10 %) were the dominant orders and are potential candidates for orchid mycorrhizal fungi. The Ascomycetes identified included the Helotiales (29.31 %), Capnodiales (18.10 %), and Sordariales (10.34 %), among others. These orders may represent potentially endophytic fungi. A Shannon–Wiener diversity index (H′) analysis showed a relatively high fungal community diversity associated with these tropical orchids. This diversity may offer greater flexibility in terms of the adaptation of the plants to changing environmental conditions and the potential facilitation of reintroduction programs. The Simpson diversity index values showed that all of the libraries included dominant species, and a LIBSHUFF analysis showed that the fungal communities were structurally different from each other, suggesting an influence of local factors on this diversity. This study offers important information for the development of conservation strategies for threatened and endemic species of Brazilian flora in an important and threatened hotspot.     

Impact of environmental variables on the isolation,diversity and antibacterial activity of endophytic fungal communities from Madhuca indica Gmel. at different locations in India

A total of 1,897 isolates of endophytic fungi from Madhuca indica Gmel., representing 40 morphologically distinct fungal taxa were obtained from 2,700 segments of stem, bark and leaf from three different locations (Loc 1, Loc 2 and Loc 3) in Uttar Pradesh, India. Out of 40 taxa, 28 were identified microscopically and the remaining 12 by molecular methods. Coelomycetes (62.41 %) were the most prevalent fungal group followed by hyphomycetes (28.89 %) and ascomycetes (8.70 %). Colonisation frequency (CF) was greater in stem (82.55 %) than in leaf (65.00 %) and bark (63.22 %). Due to the dominance of a few taxa, species richness and Shannon and Simpson diversity indices were lower in stem than in leaf and bark at each location. Interestingly, less rainfall and lower temperatures disfavoured the overall colonisation of fungal endophytes at Loc 2. The stem samples from all locations were very similar in their endophytic composition, whereas bark and leaf samples showed differences. The dominant endophytic fungi isolated were Phomopsis sp. 1 (9.185 %), and Colletotrichum gloeosporioides (7.00 %). Principal component analysis showed 55 % tissue specificity with 51.08 % maximum variance. Antibacterial activity revealed that 58.33 % endophytic fungi were active against at least one or more bacterial pathogens, whereas the crude extract of five endophytic fungi inhibited the growth of five or more than five (50 %) of the pathogens tested. This report illustrates the value of having an adequate sample size from different tissues and different locations for species and chemical diversity in search of novel natural products.     

Diversity and ecology of cultivable fungi isolated from the thermal soil gradients in Deception Island,Antarctica

We surveyed the diversity of cultivable fungi isolated from cold and hot volcanic soils of Deception Island, Antarctica. Seventy-four fungal isolates were identified; these belonged to 17 taxa in the genera Aspergillus, Penicillium, Pseudogymnoascus, Purpureocillium, and Mortierella. The fungal assemblages showed low diversity, richness, and dominance indices. The Aspergillus taxa were dominant in the soils at 0 °C, 50 °C, and 100 °C. Aspergillus lacticoffeatus, Aspergillus cf. ruber, Penicillium citrinun, and Purpureocillium sodanum were present only in soils having a temperature of 100 °C. Aspergillus calidoustus was present in all thermal soils and displayed the highest densities. The majority of fungi displayed mesophilic behavior; however, different isolates of Aspergillus lacticoffeatus and Aspergillus niger were able to grow at 50 °C; these are phylogenetically close to the causative agents of aspergillosis in immunocompromised individuals. Deception Island perhaps represents one of the most visited regions in Antarctica and the tourism there has increased over the last 20 years, especially by elderly tourists, probably with weak immune systems, come in contact with the resident microorganisms, including the thermo-resistant opportunistic Aspergillus species.

     

Diversity of endophytic fungi associated with bryophyte in the maritime Antarctic (King George Island)

Bryophytes comprise one of the richest microfungal microhabitats in the Antarctic environment. The maritime Antarctic is very vulnerable to rapid environmental change caused by global warming. The aim of this study was to investigate the importance of bryophytes as a microhabitat for fungal species in the maritime Antarctic by surveying endophytic fungal diversity from several bryophytes including Andreaea sp., Barbilophozia hatcheri, Chorisodontium aciphyllum, Polytrichum alpinum, Polytrichum strictum, Sanionia uncinata, and Warnstorfia sarmentosa. We collected 13 bryophyte samples at four localities on Barton Peninsula, King George Island. In total, 31 endophytic fungi morphotypes were isolated from bryophyte tissues by a thorough surface sterilization method. Using internal transcribed spacer sequence analysis, 16 endophytic fungal strains belonging to Ascomycota (12), Basidiomycota (1), Oomycota (1), and Zygomycota (2) phyla were obtained. Our results suggest the presence of a diverse range of fungal species even in a very limited area, and those bryophytes play an important role in conserving fungal diversity in this harsh environment. Growth rate measurements at a wide range of temperatures confirmed that most of the fungal strains were both mesophilic and psychrotolerant. This is the first report of endophytic fungi in Antarctic moss tissue by fluorescence in situ hybridization.     

Studies toward the comprehension of fungal-macroalgae interaction in cold marine regions from a biotechnological perspective

In marine ecosystems, macroalgae are the habitat for several microorganisms, fungi being among them. In the Antarctic benthic coastal ecosystem, macroalgae play a key role in organic matter cycling. In this study, 13 different macroalgae from Potter Cove and surrounding areas were sampled and 48 fungal isolates were obtained from six species, four Rhodophyta Ballia callitricha, Gigartina skottsbergii, Neuroglossum delesseriae and Palmaria decipiens, and two Phaeophyceae: Adenocystis utricularis and Ascoseira mirabilis. Fungal isolates mostly belonged to the Ascomycota phylum (Antarctomyces, Cadophora, Cladosporium, Penicillium, Phialocephala, and Pseudogymnoascus) and only one to the phylum Mucoromycota. Two of the isolates could not be identified to genus level, implying that Antarctica is a source of probable novel fungal taxa with enormous bioprospecting and biotechnological potential. 73% of the fungal isolates were moderate eurypsychrophilic (they grew at 5–25 °C), 12.5% were eurypsychrophilic and grew in the whole range, 12.5% of the isolates were narrow eurypsychrophilic (growth at 15–25 °C), and Mucoromycota AUe4 was classified as stenopsychrophilic as it grew at 5–15 °C. Organic extracts of seven macroalgae from which no fungal growth was obtained (three red algae Georgiella confluens, Gymnogongrus turquetii, Plocamium cartlagineum, and four brown algae Desmarestia anceps, D. Antarctica, Desmarestia menziesii, Himantothallus grandifolius) were tested against representative fungi of the genera isolated in this work. All extracts presented fungal inhibition, those from Plocamium cartilagineum and G. turquetii showed the best results, and for most of these macroalgae, this represents the first report of antifungal activity and constitute a promising source of compounds for future evaluation.