Deep-sea hydrothermal ecosystems are considered oases of life in oceans. Since the discovery of these ecosystems in the late 1970s, many endemic species of Bacteria, Archaea, and other organisms, such as annelids and crabs, have been described. Considerable knowledge has been acquired about the diversity of (micro)organisms in these ecosystems, but the diversity of fungi has not been studied to date. These organisms are considered key organisms in terrestrial ecosystems because of their ecological functions and especially their ability to degrade organic matter. The lack of knowledge about them in the sea reflects the widely held belief that fungi are terrestrial organisms. The first inventory of such organisms in deep-sea hydrothermal environments was obtained in this study. Fungal diversity was investigated by analyzing the small-subunit rRNA gene sequences amplified by culture-independent PCR using DNA extracts from hydrothermal samples and from a culture collection that was established. Our work revealed an unsuspected diversity of species in three of the five fungal phyla. We found a new branch of Chytridiomycota forming an ancient evolutionary lineage. Many of the species identified are unknown, even at higher taxonomic levels in the Chytridiomycota, Ascomycota, and Basidiomycota. This work opens the way to new studies of the diversity, ecology, and physiology of fungi in oceans and might stimulate new prospecting for biomolecules. From an evolutionary point of view, the diversification of fungi in the oceans can no longer be ignored.Since the discovery of hydrothermal vent ecosystems 30 years ago, unexpected species diversity has been revealed that has shed light on the functional coupling between the geosphere and the biosphere. When submersibles dive to the seafloor, they bring numerous organisms back to the surface, and this has resulted in the description of nearly two new species per month (10). Deep-sea hydrothermal ecosystems are considered hotspots of microbial diversity on the seafloor. Indeed, they are ecosystems that produce biomass using the wide range of chemical compounds released by the polymetallic sulfite chimneys or "black smokers" that represent the huge quantity of chemical energy that is available (26). The vent fluid, having been heated close to a magma chamber, can have a temperature of 400°C when it is emitted. It is also characterized by a lack of dissolved oxygen, strong acidity (pH 2 to 3), a high concentration of electron donors (i.e., reduced compounds such as methane and hydrogen sulfide), and the presence of heavy metals (36). Continual mixing with the cold ocean water (2 to 4°C) that is rich in electron acceptors creates a dynamic chemical disequilibrium that is a source of energy for microorganisms that control the rates of redox reactions (16).Each ridge displays varied geochemistry, and the vent fluids differ, even at scales as small as the fractures, pipes, and porosities in the black smokers, creating diverse microhabitats for biota (10,

As now very few studies have been carried out on deep-sea marine fungi, this field remains relatively unknown. However, their presence inside benthic microbial eukaryotes at deep-sea vents was recently pointed out from molecular microbial ecology studies. We report here an attempt to describe the culturable part of mycological communities in deep-sea vent ecosystems that is an important step in understanding their diversity, abundance and function. Physiological characterization revealed strains that are more or less adapted to deep-sea conditions. Those results suggest the presence of true marine organisms and other more ubiquitous. Phylogenetical characterization highly correlated to physiological data revealed the presence of fungi that have been previously described and unknown ones until now, belonging to new taxonomic groups. This survey encourages for further work in order to complete descriptions and also to describe the ecological role of these organisms in such extreme environments.

BackgroundIn environmental sequencing studies, fungi can be identified based on nucleic acid sequences, using either highly variable sequences as species barcodes or conserved sequences containing a high-quality phylogenetic signal. For the latter, identification relies on phylogenetic analyses and the adoption of the phylogenetic species concept.Such analysis requires that the reference sequences are well identified and deposited in public-access databases. However, many entries in the public sequence databases are problematic in terms of quality and reliability and these data require screening to ensure correct phylogenetic interpretation.Methods and Principal FindingsTo facilitate phylogenetic inferences and phylogenetic assignment, we introduce a fungal sequence database. The database PHYMYCO-DB comprises fungal sequences from GenBank that have been filtered to satisfy stringent sequence quality criteria. For the first release, two widely used molecular taxonomic markers were chosen: the nuclear SSU rRNA and EF1-α gene sequences. Following the automatic extraction and filtration, a manual curation is performed to remove problematic sequences while preserving relevant sequences useful for phylogenetic studies. As a result of curation, ∼20% of the automatically filtered sequences have been removed from the database. To demonstrate how PHYMYCO-DB can be employed, we test a set of environmental Chytridiomycota sequences obtained from deep sea samples.ConclusionPHYMYCO-DB offers the tools necessary to: (i) extract high quality fungal sequences for each of the 5 fungal phyla, at all taxonomic levels, (ii) extract already performed alignments, to act as ‘reference alignments’, (iii) launch alignments of personal sequences along with stored data. A total of 9120 SSU rRNA and 672 EF1-α high-quality fungal sequences are now available.The PHYMYCO-DB is accessible through the URL http://phymycodb.genouest.org/.

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The presence of Waddlia chondrophila has been related to respiratory tract infections and human and animal fetal death. Although several sources of infection have been suggested, the actual source remains unknown and limited information exists on the prevalence of W. chondrophila in the environment. This pathogen has been previously detected in well water but its presence has not been confirmed in water networks. Since these bacteria have been detected in water reservoirs, it has been hypothesized that they can access artificial water systems and survive until they find appropriate conditions to proliferate. In this work, their presence in water samples from 19 non-domestic water networks was tested by quantitative polymerase chain reaction (qPCR). Approximately half of the networks (47%) were positive for W. chondrophila and the overall results revealed 20% positive samples (12/59). Furthermore, most of the samples showed low concentrations of the pathogen (<200 genomic units/L). This finding demonstrates that W. chondrophila can colonize some water networks. Therefore, they must be considered as potential infection sources in future epidemiological studies.