Haloalkalitolerant Fungi from Sediments of the Big Tambukan Saline Lake (Northern Caucasus): Diversity and Antimicrobial Potential.

We have performed a characterization of cultivated haloalkalitolerant fungi from the sediments of Big Tambukan Lake in order to assess their biodiversity and antimicrobial activity. This saline, slightly alkaline lake is known as a source of therapeutic sulfide mud used in sanatoria of the Caucasian Mineral Waters, Russia. Though data on bacteria and algae observed in this lake are available in the literature, data on fungi adapted to the conditions of the lake are lacking. The diversity of haloalkalitolerant fungi was low and represented by ascomycetes of the genera Acremonium, Alternaria, Aspergillus, Chordomyces, Emericellopsis, Fusarium, Gibellulopsis, Myriodontium, Penicillium, and Pseudeurotium. Most of the fungi were characterized by moderate alkaline resistance, and they tolerated NaCl concentrations up to 10% w/v. The analysis of the antimicrobial activity of fungi showed that 87.5% of all strains were active against Bacillus subtilis, and 39.6% were also determined to be effective against Escherichia coli. The majority of the strains were also active against Aspergillus niger and Candida albicans, about 66.7% and 62.5%, respectively. These studies indicate, for the first time, the presence of polyextremotolerant fungi in the sediments of Big Tambukan Lake, which probably reflects their involvement in the formation of therapeutic muds.

Exploring Peptaibol's Profile, Antifungal, and Antitumor Activity of Emericellipsin A of Emericellopsis Species from Soda and Saline Soils.

Features of the biochemical adaptations of alkaliphilic fungi to exist in extreme environments could promote the production of active antibiotic compounds with the potential to control microorganisms, causing infections associated with health care. Thirty-eight alkaliphilic and alkalitolerant Emericellopsis strains (E. alkalina, E. cf. maritima, E. cf. terricola, Emericellopsis sp.) isolated from different saline soda soils and belonging to marine, terrestrial, and soda soil ecological clades were investigated for emericellipsin A (EmiA) biosynthesis, an antifungal peptaibol previously described for Emericellopsis alkalina. The analysis of the Emericellopsis sp. strains belonging to marine and terrestrial clades from chloride soils revealed another novel form with a mass of 1032.7 Da, defined by MALDI-TOF Ms/Ms spectrometers, as the EmiA lacked a hydroxyl (dEmiA). EmiA displayed strong inhibitory effects on cell proliferation and viability of HCT 116 cells in a dose- and time-dependent manners and induced apoptosis.

Eurotium Cristatum Postfermentation of Fireweed and Apple Tree Leaf Herbal Teas.

Fungi Eurotium spp. are the main biological agents that ferment the leaves of the Camellia sinensis tea bush to form a popular food product, postfermented tea. The fungus E. cristatum, stored in the collection of the Gause Institute of New Antibiotics under the number INA 01267, was isolated and identified from a briquette of Fujian Chinese tea. The species identification was carried out based on morphocultural characteristics and DNA sequencing. This study is aimed at determining the feasibility of making postfermented herbal teas using E. cristatum and to evaluate their quality. Autofermented herbal teas from Chamaenerion angustifolium (fireweed) and Malus domestica (apple tree) served as the starting material for this study. The change in the concentration of phenolic compounds, organic acids, sugars, and free amino acids was observed for herbal teas subjected to postfermentation with E. cristatum INA 01267. It was found that the E. cristatum INA 01267 strain does not have antimicrobial activity and does not form mycotoxins, which is an indicator of food safety.

Osmolytes and membrane lipids in the adaptation of micromycete Emericellopsis alkalina to ambient pH and sodium chloride.

The accumulation of low molecular weight cytoprotective compounds (osmolytes) and changes in the membrane lipids composition are of key importance for the adaptation to stress impacts. However, the reason behind the wide variety of osmolytes present in the cell remains unclear. We suggest that specific functions of osmolytes can be revealed by studying the adaptation mechanisms of the mycelial fungus Emericellopsis alkalina (Hypocreales, Ascomycota) that is resistant to both alkaline pH values and high sodium chloride concentrations. It has been established that the fungus uses different osmolytes to adapt to ambient pH and NaCl concentration. Arabitol was predominant osmolyte in alkaline conditions, while mannitol prevailed in acidic conditions. On the salt-free medium mannitol was the main osmolyte; under optimal conditions (pH 10.2; 0.4 M NaCl) arabitol and mannitol were both predominant. Higher NaCl concentrations (1.0-1.5 M) resulted in the accumulation of low molecular weight polyol - erythritol, which amounted up to 12-14%, w/w. On the contrary, changes in the composition of membrane lipids were limited under pH and NaCl impacts; only higher NaCl concentrations led to the increase in the degree of unsaturation of membrane lipids. Results obtained indicated the key role of the osmolytes in the adaptation to the ambient pH and osmotic impacts.

Micromycetes as colonizers of mineral building materials in historic monuments and museums.

Complex of microfungi colonizing mineral building materials, i.e. limestone and plaster, in interiors of cultural heritage was characterized. Wide-scale investigation was carried out with fourteen objects studied. We have revealed a specific culturable community. We have analyzed role of obtained microfungi in biodeterioraton process on the basis of our tests (pH and water activity preferences, ability to solubilize CaCO3) and literature data (substrate preferences and enzyme activities). The species most actively developing in mineral materials in indoor environments were Acremonium charticola, Acremonium furcatum, Lecanicillium sp., Parengyodontium album, Purpureocillium lilacinum and Sarocladium kiliense. Considering this fact and their ability to develop successfully at extremely wide range of pH values from slightly acidic to alkaline ones and their high enzymatic activities we conclude that the listed species are of high interest in seeking the cause of biodeterioration. These species can actively develop in materials penetrating for years deep into the substrates and causing their deterioration in conditions of considerably heightened moisture content. In this group, A. charticola and Lecanicillium sp. were able to solubilize CaCO3.

An unusual sexual stage in the alkalophilic ascomycete Sodiomyces alkalinus.

Exploring life cycles of fungi is insightful for understanding their basic biology and can highlight their ecology. Here, we dissected the sexual and asexual life cycles of the obligate alkalophilic ascomycete Sodiomyces alkalinus that thrives at extremely high pH of soda lakes. S.alkalinus develops acremonium-type asexual sporulation, commonly found in ascomycetous fungi. However, the sexual stage was unusual, featuring very early lysis of asci which release young ascospores inside a fruit body long before its maturation. In a young fruit body, a slimy matrix which originates from the combined epiplasm of asci and united cytoplasm of the pseudoparenchymal cells, surrounds pooled maturing ascospores. Upon maturity, the ascospores are forcibly released through a crack in the fruit body, presumably due to an increased turgor pressure. These features of the sexual stage development resemble the ones found in unrelated marine fungi, indicating convergent evolution of the trait. We hypothesise these developmental features of S. alkalinus to be adaptive in the conditions of periodically inundated rims of soda lakes where the fungus thrives.

The obligate alkalophilic soda-lake fungus Sodiomyces alkalinus has shifted to a protein diet.

Sodiomyces alkalinus is one of the very few alkalophilic fungi, adapted to grow optimally at high pH. It is widely distributed at the plant-deprived edges of extremely alkaline lakes and locally abundant. We sequenced the genome of S. alkalinus and reconstructed evolution of catabolic enzymes, using a phylogenomic comparison. We found that the genome of S. alkalinus is larger, but its predicted proteome is smaller and heavily depleted of both plant-degrading enzymes and proteinases, when compared to its closest plant-pathogenic relatives. Interestingly, despite overall losses, S. alkalinus has retained many proteinases families and acquired bacterial cell wall-degrading enzymes, some of them via horizontal gene transfer from bacteria. This fungus has very potent proteolytic activity at high pH values, but slowly induced low activity of cellulases and hemicellulases. Our experimental and in silico data suggest that plant biomass, a common food source for most fungi, is not a preferred substrate for S. alkalinus in its natural environment. We conclude that the fungus has abandoned the ancestral plant-based diet and has become specialized in a more protein-rich food, abundantly available in soda lakes in the form of prokaryotes and small crustaceans.

Membrane lipids and soluble sugars dynamics of the alkaliphilic fungus Sodiomyces tronii in response to ambient pH.

Alkaliphily, the ability of an organism to thrive optimally at high ambient pH, has been well-documented in several lineages: archaea, bacteria and fungi. The molecular mechanics of such adaptation has been extensively addressed in alkaliphilic bacteria and alkalitolerant fungi. In this study, we consider an additional property that may have enabled fungi to prosper at alkaline pH: altered contents of membrane lipids and cytoprotectant molecules. In the alkaliphilic Sodiomyces tronii, we showed that at its optimal growth pH 9.2, the fungus accumulates abundant cytosolic trehalose (4-10% dry weight) and phosphatidic acids in the membrane lipids, properties not normally observed in neutrophilic species. At a very high pH 10.2, the major carbohydrate, glucose, was rapidly substituted by mannitol and arabitol. Conversely, lowering the pH to 5.4-7.0 had major implications both on the content of carbohydrates and membrane lipids. It was shown that trehalose dominated at pH 5.4. Fractions of sphingolipids and sterols of plasma membranes rapidly elevated possibly indicating the formation of membrane structures called rafts. Overall, our results reveals complex dynamics of the contents of membrane lipids and cytoplasmic sugars in alkaliphilic S. tronii, suggesting their adaptive functionality against pH stress.

The diversity of microfungi in peatlands originated from the White Sea.

The diversity of culturable filamentous microfungi in peat and sediments of four peatlands at the coastal zone of Kandalaksha Bay of the White Sea (Murmansk region, Russia) was studied by culture methods on standard and selective media. Annually 100 samples were collected from the bogs 2007-2010. Based on morphological, molecular markers and cultural features, 211 taxa were identified. Fungal communities observed at the peatlands were influenced mostly by their sea origin. We discovered a large difference between fungal communities from the peat and the sediments of the peatlands. In contrast to the sediments, the fungal community of the peat was found to be consistent throughout sampling sites. Fungi with specific ecophysiology, such as Sphagnum-decomposing species (Oidiodendron griseum, O. tenuissimum. Penicillium spinulosum, P. thomii, Talaromyces funiculosus), psychrotolerant and associated with insects species (Pseudogymnoascus pannorum, Tolypocladium spp.), typical marine species (Acremonium spp.) were found. In addition, different types of sterile mycelia were characteristic for the researched peatlands.

Are alkalitolerant fungi of the Emericellopsis lineage (Bionectriaceae) of marine origin?

Surveying the fungi of alkaline soils in Siberia, Trans-Baikal regions (Russia), the Aral lake (Kazakhstan), and Eastern Mongolia, we report an abundance of alkalitolerant species representing the Emericellopsis-clade within the Acremonium cluster of fungi (order Hypocreales). On an alkaline medium (pH ca. 10), 34 acremonium-like fungal strains were obtained. One of these was able to develop a sexual morph and was shown to be a new member of the genus Emericellopsis, described here as E. alkalina sp. nov. Previous studies showed two distinct ecological clades within Emericellopsis, one consisting of terrestrial isolates and one predominantly marine. Remarkably, all the isolates from our study sites show high phylogenetic similarity based on six loci (LSU and SSU rDNA, RPB2, TEF1-α, ß-tub and ITS region), regardless of their provenance within a broad geographical distribution. They group within the known marine-origin species, a finding that provides a possible link to the evolution of the alkaliphilic trait in the Emericellopsis lineage. We tested the capacities of all newly isolated strains, and the few available reference ex-type cultures, to grow over wide pH ranges. The growth performance varied among the tested isolates, which showed differences in growth rate as well as in pH preference. Whereas every newly isolated strain from soda soils was extremely alkalitolerant and displayed the ability to grow over a wide range of ambient pH (range 4-11.2), reference marine-borne and terrestrial strains showed moderate and no alkalitolerance, respectively. The growth pattern of the alkalitolerant Emericellopsis isolates was unlike that of the recently described and taxonomically unrelated alkaliphilic Sodiomyces alkalinus, obtained from the same type of soils but which showed a narrower preference towards high pH.