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

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. solitumproduces 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

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

Antimycobacterial and antimalarial activities of endophytic fungi associated with the ancient and narrowly endemic neotropical plant Vellozia gigantea from Brazil

BACKGROUND Endophytic fungi, present mainly in the Ascomycota and Basidiomycota phyla, are associated with different plants and represent important producers of bioactive natural products. Brazil has a rich biodiversity of plant species, including those reported as being endemic. Among the endemic Brazilian plant species, Vellozia gigantea (Velloziaceae) is threatened by extinction and is a promising target to recover endophytic fungi. OBJECTIVE The present study focused on bioprospecting of bioactive compounds of the endophytic fungi associated with V. gigantea, an endemic, ancient, and endangered plant species that occurs only in the rupestrian grasslands of Brazil. METHODS The capability of 285 fungal isolates to produce antimicrobial and antimalarial activities was examined. Fungi were grown at solid-state fermentation to recover their crude extracts in dichloromethane. Bioactive extracts were analysed by chromatographic fractionation and NMR and displayed compounds with antimicrobial, antimycobacterial, and antimalarial activities. FINDINGS Five fungi produced antimicrobial and antimalarial compounds. Extracts of Diaporthe miriciae showed antifungal, antibacterial, and antimalarial activities; Trichoderma effusum displayed selective antibacterial activity against methicillin-resistant Staphylococcus aureus and Mycobacterium intracellulare; and three Penicillium species showed antibacterial activity. D. miriciae extract contained highly functionalised secondary metabolites, yielding the compound epoxycytochalasin H with high antimalarial activity against the chloroquine-resistant strain of Plasmodium falciparum, with an IC50 approximately 3.5-fold lower than that with chloroquine. MAIN CONCLUSION Our results indicate that V. gigantea may represent a microhabitat repository hotspot of potential fungi producers of bioactive compounds and suggest that endophytic fungal communities might be an important biological component contributing to the fitness of the plants living in the rupestrian grassland

Depth dependence of black carbon structure, elemental and microbiological composition in anthropic Amazonian dark soil

Terras Pretas de Índio are anthropic Amazonian soils rich in pyrogenic black carbon, which might be responsible for the soil long-term stability and high fertility. This black carbon, produced by the Indians while handling their residues, became a model material for agriculture and environment. The key question to answer for artificially reproducing the desired agricultural properties of the Terra Preta de Índio is whether the black carbon structure found today in these soils is the same as produced by the ancient Indians, or whether its structure results from long-term complex physical, chemical and biological activities in the soil. To address this question, this work investigates the depth dependence of the properties from a soil collected from the Balbina site, in Presidente Figueiredo, Amazonas State, Brazil. The black carbon structure and the soil composition are investigated, with special emphasis on the poorly studied microbiological composition (fungi, bacteria, arbuscular mycorrhizas). The comparative analysis between the properties from shallower (newer) and deeper (older) soil strata indicates that, while soil composition exhibits depth dependence, the pyrogenic black carbon structure does not. This finding suggests that this model material should be reproducible by repeating the pyrolysis conditions utilized in their production. © 2015 Elsevier B.V

Leishmanicidal, trypanocidal, and cytotoxic activities of endophytic fungi associated with bioactive plants in Brazil

One hundred and twenty-one isolates of endophytic fungi were recovered from leaves of the bioactive Brazilian plant species Ageratum myriadenia, Palicourea tetraphylla, Piptadenia adiantoides, and Trixis vauthieri. All fungal isolates were cultivated in liquid media and crude extracts were obtained with ethyl acetate. The crude extracts were tested in bioassay panels using Leishmania amazonensis, Trypanosoma cruzi, the enzyme trypanothione reductase (TryR) from Trypanosoma cruzi, and three human cancer cell lines. Thirty-three extracts (27.2%) exhibited at least one biological activity. Seventeen extracts (14%) were cytotoxic against one or more human cancer cell line with the IC50 values ranged of >0.2 to 25 µg/mL. Twenty-four extracts (19.8%) inhibited the activity of TryR, and three showed ability to inhibit the growth of T. cruzi above 60% and their IC50 values ranged among 1 to 10 µg/mL. Eleven extracts (9%) were able to inhibit the growth of L. amazonensis and showed with IC50 values ranged among 4.6 to 24.4 µg/mL. The endophytic fungi were identified as belonging to the genera Alternaria, Arthrinium, Cochliobolus, Colletotrichum, Penicillium, Fusarium, and Gibberella. An interesting result was obtained for the bioactive isolates UFMGCB 508, 537, 899 and 903, which were related to fungi associated with medicinal plants native to Asia, Australia, Africa, and Polynesia. These results indicate that bioactive plants living in Brazilian ecosystems are a potential host of endophytic fungi able to produce bioactive prototype molecules for drug development against neglected tropical diseases