Richness and bioactivity of culturable soil fungi from the Fildes Peninsula,Antarctica

Since the discovery of penicillin, fungi have been an important source of bioactive natural products. However, as a specific resource, the bioactive potentiality and specificity of fungal metabolites from the Antarctic region have had little attention. In this paper, we investigated the diversity patterns and biological activities of cultivable fungi isolated from soil samples in Fildes Peninsula, King George Island, Antarctica. Fungal communities showed low abundance and diversity; a total of 150 cultivable fungi were isolated from eight soil samples. After being dereplicated by morphological characteristics and chemical fingerprints, 47 fungal isolates were identified by ITS-rDNA sequencing. We confirmed that these isolates belonged to at least 11 different genera and clustered into nine groups corresponding to taxonomic orders in the phylogenetic analysis. Using two different fermentation conditions, 94 crude extracts acquired from the abovementioned different metabolite characteristic isolates were screened by bioactivity assay and 18 isolates produced biologically active compounds. Compared with HPLC–DAD–UV fingerprint analysis of culture extracts and standard compounds, two bioactive components secalonic acid and chetracins were identified. Our research suggests that the abundance and diversity of Antarctic cultivable fungal communities exhibit unique ecological characteristics and potential producers of novel natural bioactive products.     

Perspectives on the potential of entomopathogenic fungi in biological control of ticks

Ticks are serious health threats for humans, and both domestic and wild animals. Ticks are controlled mostly by application of chemical products; but these acaricides have several negative side effects, including toxicity to animals, environmental contamination, and induction of chemical resistance in some tick populations. Entomopathogenic fungi infect arthropods in nature and can occur at enzootic or epizootic levels in their host populations. Laboratory studies clearly demonstrate that these fungi can cause high mortality in all developmental stages of several tick species, and also reduce oviposition of infected engorged females. Tick mortality following application of fungi in the field, however, often is less than that suggested by laboratory tests. This is due to many negative biotic and climatic factors. To increase efficacy of fungal agents for biological control of ticks under natural conditions, several points need consideration: (1) select effective isolates (viz., high virulence; and tolerance to high temperature, ultraviolet radiation and desiccation); (2) understand the main factors that affect virulence of fungal isolates to their target arthropods including the role of toxic metabolites of the fungal isolates; and (3) define with more precision the immune response of ticks to infection by entomopathogenic fungi. The current study reviews recent literature on biological control of ticks, and comments on the relevance of these results to advancing the development of fungal biocontrol agents, including improving formulation of fungal spores for use in tick control, and using entomopathogenic fungi in integrated pest (tick) management programs.     

Collembola foraging responses to interacting fungi

Abstract 1. Temperate woodland Collembola feed predominantly on plant detritus and fungi. They exhibit preferences for different fungi reflecting resource value in terms of Collembola growth and reproduction. 2. Studies of fungal grazing by Collembola have focused on non‐interacting fungi and have used one genetic isolate as representative of an entire fungal species. This study examines the effects of fungal interactions on Collembola behaviour, and elucidates differences arising from the use of genetically distinct fungal isolates. 3. Folsomia candida were added to microcosms in which paired combinations of the fungi, Hypholoma fasciculare (four isolates), Phallus impudicus, Phanerochetae velutina and Resinicium bicolor (two isolates), were interacting. Collembola movement and mortality was recorded for 26 days. A constant preference for one fungal mycelium over the other was shown by Collembola in 12 of the 36 interactions studied. Lowest Collembola mortality was normally recorded on the preferred mycelium. 4. In 11 of the remaining 24 interactions, Collembola preference switched from one mycelium to the other; the greatest number of dead Collembola was recorded on the final preference. 5. Collembola behaviour on different fungal isolates was broadly similar, although in one species’ combination a change in fungal isolate resulted in a total reversal of Collembola preference. The implications of these results for decomposer food webs are considered.     

Isolation, characterization, and avenacin sensitivity of a diverse collection of cereal-root-colonizing fungi.

A total of 161 fungal isolates were obtained from the surface-sterilized roots of field-grown oat and wheat plants in order to investigate the nature of the root-colonizing fungi supported by these two cereals. Fungi were initially grouped according to their colony morphologies and then were further characterized by ribosomal DNA sequence analysis. The collection contained a wide range of ascomycetes and also some basidiomycete fungi. The fungi were subsequently assessed for their abilities to tolerate and degrade the antifungal oat root saponin, avenacin A-1. Nearly all the fungi obtained from oat roots were avenacin A-1 resistant, while both avenacin-sensitive and avenacin-resistant fungi were isolated from the roots of the non-saponin-producing cereal, wheat. The majority of the avenacin-resistant fungi were able to degrade avenacin A-1. These experiments suggest that avenacin A-1 is likely to influence the development of fungal communities within (and possibly also around) oat roots.     

Isolation, Characterization, and Avenacin Sensitivity of a Diverse Collection of Cereal-Root-Colonizing Fungi

A total of 161 fungal isolates were obtained from the surface-sterilized roots of field-grown oat and wheat plants in order to investigate the nature of the root-colonizing fungi supported by these two cereals. Fungi were initially grouped according to their colony morphologies and then were further characterized by ribosomal DNA sequence analysis. The collection contained a wide range of ascomycetes and also some basidiomycete fungi. The fungi were subsequently assessed for their abilities to tolerate and degrade the antifungal oat root saponin, avenacin A-1. Nearly all the fungi obtained from oat roots were avenacin A-1 resistant, while both avenacin-sensitive and avenacin-resistant fungi were isolated from the roots of the non-saponin-producing cereal, wheat. The majority of the avenacin-resistant fungi were able to degrade avenacin A-1. These experiments suggest that avenacin A-1 is likely to influence the development of fungal communities within (and possibly also around) oat roots.     

Soil fungi invest into asexual sporulation under resource scarcity,but trait spaces of individual isolates are unique

During the last few decades, a plethora of sequencing studies provided insight into fungal community composition under various environmental conditions. Still, the mechanisms of species assembly and fungal spread in soil remain largely unknown. While mycelial growth patterns are studied extensively, the abundant formation of asexual spores is often overlooked, though representing a substantial part of the fungal life cycle relevant for survival and dispersal. Here, we explore asexual sporulation (spore abundance, size and shape) in 32 co-occurring soil fungal isolates under varying resource conditions, to answer the question whether resource limitation triggers or inhibits fungal investment into reproduction. We further hypothesized that trade-offs exist in fungal investment towards growth, spore production and size. The results revealed overall increased fungal investment into spore production under resource limitations; however, effect sizes and response types varied strongly among fungal isolates. Such isolate-specific effects were apparent in all measured traits, resulting in unique trait spaces of individual isolates. This comprehensive dataset also elucidated variability in sporulation strategies and trade-offs with fungal growth and reproduction under resource scarcity, as only predicted by theoretical models before. The observed isolate-specific strategies likely underpin mechanisms of co-existence in this diverse group of saprobic soil fungi.     

Phylogenetic analysis and antifouling potentials of culturable fungi in mangrove sediments from Techeng Isle,China

To search for more microbial resources for screening environment-friendly antifoulants, we investigated the phylogenetic diversity and antifouling potentials of culturable fungi in mangrove sediments from Techeng Isle, China. A total of 176 isolates belonging to 57 fungal taxa were recovered and identified. The high levels of diversity and abundance of mangrove fungi from Techeng Isle were in accordance with previous studies on fungi from other mangrove ecosystems. Fifteen of the 176 isolates demonstrated high divergence (87–93%) from the known fungal taxa in GenBank. Moreover, 26 isolates recorded in mangrove ecosystems for the first time. These results suggested that mangrove sediments from Techeng Isle harbored some new fungal communities compared with other mangrove ecosystems. The antifouling activity of 57 representative isolates (belonging to 57 different fungal taxa) was tested against three marine bacteria (Loktanella hongkongensis, Micrococcus luteus and Pseudoalteromonas piscida) and two marine macrofoulers (bryozoan Bugula neritina and barnacle Balanus amphitrite). Approximately 40% of the tested isolates displayed distinct antifouling activity. Furthermore, 17 fungal isolates were found to display strong or a wide spectrum of antifouling activity in this study, suggesting that these isolates deserve further study as potential sources of novel antifouling metabolites. To our knowledge, this is the first report on the investigation of the phylogenetic diversity and antifouling potential of culturable fungi in mangrove sediments from Techeng Isle, China. These results contribute to our knowledge of mangrove fungi and further increases the pool of fungi available for natural bioactive product screening.     

Mycorrhizas improve nitrogen nutrition of Trifolium repens after 8 yr of selection under elevated atmospheric CO2 partial pressure

Altered environmental conditions may change populations of arbuscular mycorrhizal fungi and thereby affect mycorrhizal functioning. We investigated whether 8 yr of free-air CO2 enrichment has selected fungi that differently influence the nutrition and growth of host plants. In a controlled pot experiment, two sets of seven randomly picked single spore isolates, originating from field plots of elevated (60 Pa) or ambient CO2 partial pressure (pCO2), were inoculated on nodulated Trifolium repens (white clover) plants. Fungal isolates belonged to the Glomus claroideum or Glomus intraradices species complex, and host plants were clonal micropropagates derived from nine genets. Total nitrogen (N) concentration was increased in leaves of plants inoculated with fungal isolates from elevated-pCO2 plots. These isolates took up nearly twice as much N from the soil as isolates from ambient-pCO2 plots and showed much greater stimulation of biological N2 fixation. The morpho-species identity of isolates had a more pronounced effect on N2 fixation and on root length colonized than isolate identity. We conclude that rising atmospheric pCO2 may select for fungal strains that will help their host plants to meet increased N demands.     

Large‐scale molecular genetic analysis in plant‐pathogenic fungi: a decade of genome‐wide functional analysis

Plant‐pathogenic fungi cause diseases to all major crop plants world‐wide and threaten global food security. Underpinning fungal diseases are virulence genes facilitating plant host colonization that often marks pathogenesis and crop failures, as well as an increase in staple food prices. Fungal molecular genetics is therefore the cornerstone to the sustainable prevention of disease outbreaks. Pathogenicity studies using mutant collections provide immense function‐based information regarding virulence genes of economically relevant fungi. These collections are rich in potential targets for existing and new biological control agents. They contribute to host resistance breeding against fungal pathogens and are instrumental in searching for novel resistance genes through the identification of fungal effectors. Therefore, functional analyses of mutant collections propel gene discovery and characterization, and may be incorporated into disease management strategies. In the light of these attributes, mutant collections enhance the development of practical solutions to confront modern agricultural constraints. Here, a critical review of mutant collections constructed by various laboratories during the past decade is provided. We used Magnaporthe oryzae and Fusarium graminearum studies to show how mutant screens contribute to bridge existing knowledge gaps in pathogenicity and fungal–host interactions.     

布莱克韦尔虫草的生物活性评价及其子实体的人工培育

虫草在世界范围内广泛分布,具有多种生物活性及较高的食药用价值。为进一步丰富虫草真菌资源,本研究对从广东韶关丹霞山采集到的一份野生虫草样品进行了菌株的分离鉴定、生物活性评价和子实体的诱导培养。通过形态学和系统发育分析,将菌株ZYJ0835鉴定为布莱克韦尔虫草Cordyceps blackwelliae。利用5种不同的培养基进行液体发酵培养,发现该菌株的发酵上清液和菌丝体均具有抗氧化和纤溶活性。此外,该菌株还具有一定的抑菌活性。利用大米、小麦、柞蚕蛹3种培养基质,均成功诱导出子实体,并且人工培养的子实体也具有抗氧化和纤溶活性。本研究首次在中国境内报道布莱克韦尔虫草的分布,为进一步开发利用该虫草资源提供了理论依据。     

The effects of arbuscular mycorrhizal (AM) fungal and garlic mustard introductions on native AM fungal diversity

Introduced, non-native organisms are of global concern, because biological invasions can negatively affect local communities. Arbuscular mycorrhizal (AM) fungal communities have not been well studied in this context. AM fungi are abundant in most soils, forming symbiotic root-associations with many plant species. Commercial AM fungal inocula are increasingly spread worldwide, because of potentially beneficial effects on plant growth. In contrast, some invasive plant species, such as the non-mycorrhizal Alliaria petiolata, can negatively influence AM fungi. In a greenhouse study we examined changes in the structure of a local Canadian AM fungal community in response to inoculation by foreign AM fungi and the manipulated presence/absence of A. petiolata. We expected A. petiolata to have a stronger effect on the local AM fungal community than the addition of foreign AM fungal isolates. Molecular analyses indicated that inoculated foreign AM fungi successfully established and decreased molecular diversity of the local AM fungal community in host roots. A. petiolata did not affect molecular diversity, but reduced AM fungal growth in the greenhouse study and in a in vitro assay. Our findings suggest that both introduced plants and exotic AM fungi can have negative impacts on local AM fungi.     

Culturable Endophytes Associated with Soybean Seeds and Their Potential for Suppressing Seed-Borne Pathogens

Seed-borne pathogens in crops reduce the seed germination rate and hamper seedling growth, leading to significant yield loss. Due to the growing concerns about environmental damage and the development of resistance to agrochemicals among pathogen populations, there is a strong demand for eco-friendly alternatives to synthetic chemicals in agriculture. It has been well established during the last few decades that plant seeds harbor diverse microbes, some of which are vertically transmitted and important for plant health and productivity. In this study, we isolated culturable endophytic bacteria and fungi from soybean seeds and evaluated their antagonistic activities against common bacterial and fungal seed-borne pathogens of soybean. A total of 87 bacterial isolates and 66 fungal isolates were obtained. Sequencing of 16S rDNA and internal transcribed spacer amplicon showed that these isolates correspond to 30 and 15 different species of bacteria and fungi, respectively. Our antibacterial and antifungal activity assay showed that four fungal species and nine bacterial species have the potential to suppress the growth of at least one seed-borne pathogen tested in the study. Among them, Pseudomonas koreensis appears to have strong antagonistic activities across all the pathogens. Our collection of soybean seed endophytes would be a valuable resource not only for studying biology and ecology of seed endophytes but also for practical deployment of seed endophytes toward crop protection.     

Variation in tolerance and virulence in the chestnut blight fungus-hypovirus interaction

Chestnut blight, caused by the fungus Cryphonectria parasitica, has been effectively controlled with double-stranded RNA hypoviruses in Europe for over 40 years. The marked reduction in the virulence of C. parasitica by hypoviruses is a phenomenon known as hypovirulence. This virus-fungus pathosystem has become a model system for the study of biological control of fungi with viruses. We studied variation in tolerance to hypoviruses in fungal hosts and variation in virulence among virus isolates from a local population in Italy. Tolerance is defined as the relative fitness of a fungal individual when infected with hypoviruses (compared to being uninfected); virulence is defined for each hypovirus as the reduction in fitness of fungal hosts relative to virus-free hosts. Six hypovirus-infected isolates of C. parasitica were sampled from the population, and each hypovirus was transferred into six hypovirus-free recipient isolates. The resulting 36 hypovirus-fungus combinations were used to estimate genetic variation in tolerance to hypoviruses, in hypovirus virulence, and in virus-fungus interactions. Four phenotypes were evaluated for each virus-fungus combination to estimate relative fitness: (i) sporulation, i.e., the number of asexual spores (conidia) produced; (ii) canker area on field-inoculated chestnut trees, (iii) vertical transmission of hypoviruses into conidia, and (iv) conidial germination. Two-way analysis of variance (ANOVA) revealed significant interactions (P < 0.001) between viruses and fungal isolates for sporulation and canker area but not for conidial germination or transmission. One-way ANOVA among hypoviruses (within each fungal isolate) and among fungal isolates (within each hypovirus) revealed significant genetic variation (P < 0.01) in hypovirus virulence and fungal tolerance within several fungal isolates, and hypoviruses, respectively. These interactions and the significant genetic variation in several fitness characters indicate the potential for future evolution of these characters. However, biological control is unlikely to break down due to evolution of tolerance to hypoviruses in the fungus because the magnitudes of tolerance and interactions were relatively small.     

Variation in Tolerance and Virulence in the Chestnut Blight Fungus-Hypovirus Interaction

Chestnut blight, caused by the fungus Cryphonectria parasitica, has been effectively controlled with double-stranded RNA hypoviruses in Europe for over 40 years. The marked reduction in the virulence of C. parasitica by hypoviruses is a phenomenon known as hypovirulence. This virus-fungus pathosystem has become a model system for the study of biological control of fungi with viruses. We studied variation in tolerance to hypoviruses in fungal hosts and variation in virulence among virus isolates from a local population in Italy. Tolerance is defined as the relative fitness of a fungal individual when infected with hypoviruses (compared to being uninfected); virulence is defined for each hypovirus as the reduction in fitness of fungal hosts relative to virus-free hosts. Six hypovirus-infected isolates of C. parasitica were sampled from the population, and each hypovirus was transferred into six hypovirus-free recipient isolates. The resulting 36 hypovirus-fungus combinations were used to estimate genetic variation in tolerance to hypoviruses, in hypovirus virulence, and in virus-fungus interactions. Four phenotypes were evaluated for each virus-fungus combination to estimate relative fitness: (i) sporulation, i.e., the number of asexual spores (conidia) produced; (ii) canker area on field-inoculated chestnut trees, (iii) vertical transmission of hypoviruses into conidia, and (iv) conidial germination. Two-way analysis of variance (ANOVA) revealed significant interactions (P < 0.001) between viruses and fungal isolates for sporulation and canker area but not for conidial germination or transmission. One-way ANOVA among hypoviruses (within each fungal isolate) and among fungal isolates (within each hypovirus) revealed significant genetic variation (P < 0.01) in hypovirus virulence and fungal tolerance within several fungal isolates, and hypoviruses, respectively. These interactions and the significant genetic variation in several fitness characters indicate the potential for future evolution of these characters. However, biological control is unlikely to break down due to evolution of tolerance to hypoviruses in the fungus because the magnitudes of tolerance and interactions were relatively small.     

降解全氟辛酸真菌的分离与鉴定

目的 通过富集培养分离降解全氟辛酸（PFOA）的真菌,进行分类鉴定和降解特性分析。方法 采集全氟化合物污染的土壤,利用以PFOA为唯一碳源的无机盐培养基进行驯化和富集培养,分离降解PFOA的真菌;通过形态观察和基于ITS基因序列的系统发育分析对分离菌株进行鉴定;采用LC-MS检测其降解PFOA的能力。结果 分离获得2株降解PFOA的真菌AF1和AF2,初步鉴定分别为棘孢木霉（Trichoderma asperellum）和棘卷枝毛霉（Mucor circinelloides）;胞外酶活性分析均具有漆酶活性。真菌AF1和AF2在以PFOA为唯一碳源的无机盐培养基中培养72 h后,最大降解率分别为24.24%和28.12%。结论 自然环境中蕴藏着降解PFOA的真菌资源。     

Impacts of elevated temperature on the growth and functioning of decomposer fungi are influenced by grazing collembola

Elevated temperature has potential to influence the biological mechanisms regulating ecosystem–atmosphere carbon exchange. The relationship between warming and heterotrophic microbial respiration remains poorly understood, not least in terms of the differential sensitivity of microbial groups to temperature and the complexity of interactions with other biota. Cord‐forming basidiomycete fungi are dominant primary decomposers in temperate woodland. Decomposition rates are determined by the composition of the decomposer community, ecophysiological relationships between these fungi and abiotic variables and interactions with other organisms. Amongst the latter, a major determinant is the balance between mycelial growth and removal by soil invertebrate grazers, which can themselves be affected by elevated temperature. We investigated the impact of elevated temperature on fungal foraging and decomposition of beech (Fagus sylvatica) wood in soil microcosms to which the invertebrate grazers, Folsomia candida and Protophorura armata (Collembola), were added in factorial combinations with five basidiomycete fungi. Species‐specific impacts on mycelial development and function resulted from differential sensitivity of fungi to warming and grazing. Temperature impacts on collembola abundance were resource‐specific, causing increased grazing pressure by both species, but on different fungi. Grazing often counteracted warming‐induced stimulation of mycelial growth, but occasionally amplified the temperature effect, with implications for colonization rates of new resources. High grazing pressure did not prevent increased fungal‐mediated decomposition of colonized wood, as fungi utilized more resource‐derived energy to maintain explorative growth. Impacts of elevated temperature on decomposition are likely to depend on local composition of the fungal and invertebrate decomposer community.     

Susceptibility of Dendroctonus simplex to Hypocreales fungi: towards the development of a biological control strategy

The use of Hypocreales fungi against bark beetles is an attractive alternative strategy for biological control in forestry. However, fungal inoculation methods remain a major challenge due to the cryptic behaviour of these beetles. Experiments were conducted to evaluate the susceptibility of adult eastern larch beetles, Dendroctonus simplex, to different isolates of Hypocreales fungi and to assess the efficiency of direct inoculation of fungal conidia using an assisted autodissemination device. Among the nine fungal isolates tested, Beauveria bassiana INRS‐242 was selected as the utmost isolate causing a mortality rate of 64.4% of D. simplex adults within 10 days and having a high conidial viability of 81.7%. Using an assisted autodissemination device, a fungal‐coated pouch was a promising contamination chamber. Once it had fallen onto the fungal‐coated pouch, each D. simplex adult loaded an average lethal dose of 2.1 × 10⁹ conidia, which induced a mortality rate of 98.0%. Our results demonstrated the fungal pathogenicity of B. bassiana INRS‐242 against the eastern larch beetles and pointed out the potential of the assisted autodissemination device as an effective method of conidia inoculation. These findings represent the first step to develop a biological control strategy against D. simplex populations.     

Susceptibility of adult Aedes aegypti (Diptera: Culicidae) to infection by Metarhizium anisopliae and Beauveria bassiana: prospects for Dengue vector control

Dengue fever vectored by the mosquito Aedes aegypti is one of the most rapidly spreading insect-borne diseases, stimulating the search for alternatives to current control methods. Screening assays using a range of Metarhizium anisopliae and Beauveria bassiana isolates were performed against adult female Ae. aegypti. Four virulent isolates were selected for detailed study. Adult female mosquitoes were exposed to supports previously inoculated with fungal suspensions. Fungal isolates were suspended in Tween 80+8% vegetable oil. The isolates caused between 70 and 89% mortality as a result of fungal infection over the 7-day test period. Mean survival times varied between 3 and 5 days for treated insects, whilst control survival exceeded 40 days. The most promising isolate, M. anisopliae LPP133, based not only on virulence but facility for mass production, was used for lethal exposure time determinations. An exposure time of only 3.5 h was necessary to cause 50% mortality. Large cage trails were also carried out and mean survival time of insects exposed to fungus impregnated black cloths was significantly reduced. These results show that entomopathogenic fungi could be promising biological control agents for use against adult Ae. aegypti, by inoculating fungi onto surfaces on which the mosquitoes tend to rest. The subsequent mortality caused by the fungi could potentially reduce the populations of this insect thus reducing the incidence of Dengue.     

Distribution,occurrence and characterization of entomopathogenic fungi in agricultural soil in the Palestinian area

The occurrence of entomopathogenic fungi was investigated in irrigated vegetable fields and citrus orchards soils, over a nine-month period (April-December 1999),using the Galleria bait method (GBM). Entomopathogenic fungi were found to occur in 33.6% of the soil samples studied, with positive samples yielding 70 fungal isolates, belonging to 20 species from 13 genera. Conidiobolus coronatus was the most frequent and abundant entomopathogenic species recovered, comprising 31.4% of the total number of isolates. Soil pH, soil moisture content and the geographical location had minor or no effect on the isolation of entomopathogenic fungi in the fields studied. On the other hand, organic matter content of soil, and vegetation type were found to significantly affect the occurrence of entomopathogenic fungi in soil habitats, with orchard fields yielding larger numbers of isolates than vegetable fields. Using Koch's postulates the pathogenicity of fungal isolates to Galleria larvae was found to range from 16–100% (mortality rate). Isolates of C. coronatus proved to be the most virulent isolates recovered. The effect of media and temperature on mycelial growth rate, conidial production and conidial germination of six entomopathogenic fungal species (C. coronatus, Entomophaga grylli, Erynia castrans, Hirsutella jonesii, Paecilomyces farinosus and Sporodiniella umbellata) was also studied. Mycelial growth rate, spore production and spore germination were significantly affected by media, temperature and isolates. In view of the present results, C. coronatus appears to be a good candidate for pest control in agricultural soils, as it has a wide tolerance to agricultural practices, has frequently been isolated from both vegetable and orchard fields, and is characterized by high mycelial growth rate, conidial production and conidial germination.This revised version was published online in October 2005 with corrections to the Cover Date.     

Diversity of cultivable fungi associated with Antarctic marine sponges and screening for their antimicrobial, antitumoral and antioxidant potential

The diversity of sponge-associated fungi has been poorly investigated in remote geographical areas like Antarctica. In this study, 101 phenotypically different fungal isolates were obtained from 11 sponge samples collected in King George Island, Antarctica. The analysis of ITS sequences revealed that they belong to the phylum Ascomycota. Sixty-five isolates belong to the genera Geomyces, Penicillium, Epicoccum, Pseudeurotium, Thelebolus, Cladosporium, Aspergillus, Aureobasidium, Phoma, and Trichocladium but 36 isolates could not be identified at genus level. In order to estimate the potential of these isolates as producers of interesting bioactivities, antimicrobial, antitumoral and antioxidant activities of fungal culture extracts were assayed. Around 51 % of the extracts, mainly from the genus Geomyces and non identified relatives, showed antimicrobial activity against some of the bacteria tested. On the other hand, around 42 % of the extracts showed potent antitumoral activity, Geomyces sp. having the best performance. Finally, the potential of the isolated fungi as producers of antioxidant activity seems to be moderate. Our results suggest that fungi associated with Antarctic sponges, particularly Geomyces, would be valuable sources of antimicrobial and antitumoral compounds. To our knowledge, this is the first report describing the biodiversity and the metabolic potential of fungi associated with Antarctic marine sponges.