S. Onofri

Drought meets acid: three new genera in a dothidealean clade of extremotolerant fungi.

Fungal strains isolated from rocks and lichens collected in the Antarctic ice-free area of the Victoria Land, one of the coldest and driest habitats on earth, were found in two phylogenetically isolated positions within the subclass Dothideomycetidae. They are here reported as new genera and species, Recurvomyces mirabilis gen. nov., sp. nov. and Elasticomyces elasticus gen. nov., sp. nov. The nearest neighbours within the clades were other rock-inhabiting fungi from dry environments, either cold or hot. Plant-associated Mycosphaerella-like species, known as invaders of leathery leaves in semi-arid climates, are also phylogenetically related with the new taxa. The clusters are also related to the halophilic species Hortaea werneckii, as well as to acidophilic fungi. One of the latter, able to grow at pH 0, is Scytalidium acidophilum, which is ascribed here to the newly validated genus Acidomyces. The ecological implications of this finding are discussed.

Resistance of Antarctic black fungi and cryptoendolithic communities to simulated space and Martian conditions.

Dried colonies of the Antarctic rock-inhabiting meristematic fungi Cryomyces antarcticus CCFEE 515, CCFEE 534 and C. minteri CCFEE 5187, as well as fragments of rocks colonized by the Antarctic cryptoendolithic community, were exposed to a set of ground-based experiment verification tests (EVTs) at the German Aerospace Center (DLR, Köln, Germany). These were carried out to test the tolerance of these organisms in view of their possible exposure to space conditions outside of the International Space Station (ISS). Tests included single or combined simulated space and Martian conditions. Responses were analysed both by cultural and microscopic methods. Thereby, colony formation capacities were measured and the cellular viability was assessed using live/dead dyes FUN 1 and SYTOX Green. The results clearly suggest a general good resistance of all the samples investigated. C. minteri CCFEE 5187, C. antarcticus CCFEE 515 and colonized rocks were selected as suitable candidates to withstand space flight and long-term permanence in space on the ISS in the framework of the LIchens and Fungi Experiments (LIFE programme, European Space Agency).

Phylogeny and taxonomy of meristematic rock-inhabiting black fungi in the Dothideomycetes based on multi-locus phylogenies

The last decade has revealed an unexpected fungal diversity associated with natural rocks, often collected in environments influenced by harsh climatic conditions. Yet the phylogenetic affiliations and the taxonomy of many of these extreme fungi, mainly within Dothideomycetes, the largest class of Ascomycota, have only partially been described. In the present study we confirm that most rock inhabiting-fungi (RIF) are highly polyphyletic among Dothideomycetidae, mainly within the order Capnodiales, an order otherwise incorporating several families of major plant pathological importance. Novel taxa were identified within the two major and distinct clades of Teratosphaeriaceae, both comprising meristematic black fungi. Thirty one novel species and 13 new genera are proposed, based on ITS and partial nucLSU, RPB2 and BT2 sequences.

Searching for eukaryotic life preserved in Antarctic permafrost

Fungi and yeasts isolated in pure culture from Antarctic permafrost collected at different depths in the McMurdo Dry Valleys were identified with cultural, physiological and molecular methods. Fungi belonged to the genera Penicillium, Eurotium, Cladosporium, Alternaria, Engyodonthium, Aureobasidium, Cordyceps, Rhizopus and yeasts to the genera Cryptococcus and Sporidiobolus. All the strains can be defined as mesophilic psychrotolerant. The molecular analyses revealed that these fungal genotypes do not deviate from the global gene pool of fungi commonly spreading worldwide at present, but possible ancestral strains have been found on the base of metabolic profiles.

Viability of the lichen Xanthoria elegans and its symbionts after 18 months of space exposure and simulated Mars conditions on the ISS

The lichen Xanthoria elegans has been exposed to space conditions and simulated Mars-analogue conditions in the lichen and fungi experiment (LIFE) on the International Space Station (ISS). After several simulations and short space exposure experiments such as BIOPAN, this was the first long-term exposure of eukaryotic organisms to the hostile space conditions of the low Earth orbit (LEO). The biological samples were integrated in the EXPOSE-E facility and exposed for 1.5 years outside the ISS to the combined impact of insolation, ultraviolet (UV)-irradiation, cosmic radiation, temperatures and vacuum conditions of LEO space. Additionally, a subset of X. elegans samples was exposed to simulated Martian environmental conditions by applying Mars-analogue atmosphere and suitable solar radiation filters. After their return to Earth the viability of the lichen samples was ascertained by viability analysis of LIVE/DEAD staining and confocal laser-scanning microscopy, but also by analyses of chlorophyll a fluorescence. According to the LIVE/DEAD staining results, the lichen photobiont showed an average viability rate of 71%, whereas the even more resistant lichen mycobiont showed a rate of 84%. Post-exposure viability rates did not significantly vary among the applied exposure conditions. This remarkable viability is discussed in the context of particular protective mechanisms of lichens such as anhydrobiosis and UV-screening pigments.

Effects of UV on the spores of the fungal species Arthrobotrys oligospora and A. ferox

Abstract. The effects of UV irradiation (at λ>380xa0nm and λ>265xa0nm) on spore suspensions of a European strain of Arthrobotrys oligospora (hyphomycete) have been investigated and compared with those on a strain of the Antarctic species, A. ferox. Emission and excitation spectra of control and irradiated spore suspensions of both strains suggest a higher vulnerability of A. oligospora, which would be consistent with changes in membrane permeability and a lower amount of UV-protecting substances. Germination tests on UV-B irradiated spores confirm the higher resistance of A. ferox, which seems better adapted to the high UV radiation levels characterizing Antarctic environments.

Biodiversity of rock, beach and water fungi in Italy

Abstract The fungal biodiversity in its overall is mostly still unknown and the ecological role of these organisms, particularly in some border ecosystems, is often underestimated. This study aims to give both an overview of the state of the art and to present new data on the mycodiversity in some peculiar environments as rocks, beach sand, and water in Italy. Particularly, rock fungi are here reported from high mountain peaks, sea cliffs, and monuments; sand associated fungi from beach ecosystems in Puglia and Ligurian coasts; marine fungi associated with the endemic seagrass of the Mediterranean Posidonia oceanica L.; aquatic hyphomycetes (Ingoldian fungi) from both streams in the Ticino Natural Park and lentic water in Lago Maggiore; fungi from the water distribution system in Turin. Ecological and evolutive considerations are put forward.

Mountain tips as reservoirs for new rock-fungal entities: Saxomyces gen. nov. and four new species from the Alps

As part of a worldwide sampling nine black fungi were isolated from rocks collected in four distinct sites of the Alps at high altitudes. Based on a nucSSU, nucLSU and mtSSU multi-locus phylogeny, seven of them were found to cluster into a distinct and well-supported clade in a basal position within the Class Dothideomycetes. As in other rock fungi these new groups of isolates were characterized by a meristematic growth and a scarcely differentiated morphology with highly melanized and thick-walled toruloid hyphae. Nonetheless, few peculiar characters were also observed as convoluted hyphal tips and the production of spherical propagules. The new genus and species Saxomyces alpinus and S. penninicus, are here described based on morphological and molecular data, in a yet to be defined order of the Dothideomycetes. The remaining two black fungi clustered in Cryomyces, a genus previously exclusively found in rocks from the McMurdo Dry Valleys in Antarctica. These two isolates were genetically distant from other Antarctic Cryomyces species based on ITS sequences, and they showed a peculiar morphology; they are here described as the new species C. montanus and C. funiculosus. Implications of our results on the evolution, adaptation and dispersal of rock-inhabiting fungi under extreme conditions are discussed.

Rock-inhabiting fungi and their role in deterioration of stone monuments in the Mediterranean area

Most of the cultural heritage is in the Mediterranean area. Stone was historically the most durable and widely used building material; therefore, the greatest deal of antiques is represented by stone monuments located in outdoor environments. Atmospheric agents, pollution, and various stresses are the main causes of deterioration of artistic heritage as well as many micro-organisms that often cause irreversible damages. Conservation of this invaluable patrimony, therefore, is a demanding challenge. Rock-inhabiting fungi (RIF) are very active agents causing visible alteration patterns and exfoliation of stone monuments; ecological conditions in the Mediterranean rocks are optimal for RIF development. Along with environmental conditions, fungal colonization depends also on bioreceptivity of the surfaces and survival strategies of colonizing species. This paper represents an overview of RIF biodiversity on stone monuments known at present, mechanisms of attack and colonization and outdoor conditions allowing the settlement of RIF propagules, colonization, and the following biodeterioration processes.

Do fungi survive under actual space conditions? Searching for evidence in favour of lithopanspermia

Abstract Cryptoendolithic communities and black meristematic fungi from the Antarctic desert have been shown to survive under simulated space and Martian conditions in ground‐based Experiment Verification Tests. An experiment was set to test their resistance under actual space and simulated Martian conditions on the International Space Station in the framework of the EXPOSE‐EuTEF Consortium, LIFE‐ESA project.