N. E. Ivanushkina

Halo-and psychrotolerant Geomyces fungi from arctic cryopegs and marine deposits

Comparative characterization of Geomyces isolates was performed. The isolates were obtained from Arctic cryopegs and the surrounding ancient marine deposits, from nonsaline permafrost soils, and from temperate environments. Microbiological (cultural and morphological) and molecular criteria were used to confirm the identification of the isolates as Geomyces pannorum. The isolates from cryopegs and surrounding marine deposits were shown to differ from those obtained from nonsaline soils and temperate environments in their ability to grow at negative temperatures (−2°C) under increased salt concentration (10%). The results are discussed in relation to the possible inheritance of the adaptive characteristics acquired in specific environments.

Production of mycophenolic acid by fungi of the genus Penicillium link

Out of 36 strains of fungi of the genus Penicillium, some of which were isolated from ancient permafrost, 14 strains synthesized mycophenolic acid (MPA). Maximal (over 500 mg/l) accumulation of MPA in culture liquid was observed in P. brevicompactum strains (VKM F-457, VKM F-477, and VKM F-1150). This was the first study to detect MPA in representatives of the species P. rugulosum; in three strains of this species (VKM FW-665, VKM FW-717, and VKM FW-733), the level of MPA accumulation exceeded 300 mg/l. The time course of the synthesis of MPA by P. rugulosum strain VKM FW-733 was studied. It was shown that the synthesis of this metabolite was dramatically intensified during the stationary growth phase (ten days).

Ancient fungi in Antarctic permafrost environments

Filamentous fungi in 36 samples of Antarctic permafrost sediments were studied. The samples collected during the Russian Antarctic expedition of 2007-2009 within the framework of the Antarctic Permafrost Age Project (ANTPAGE) were recovered from different depths in ice-free oases located along the perimeter of the continent. Fungal diversity was determined by conventional microbiological techniques combined with a culture-independent method based on the analysis of internal transcribed spacer (ITS2) sequences in total DNA of the samples. The study revealed a rather low fungal population density in permafrost, although the diversity found was appreciable, representing more than 26 genera. Comparison of the data obtained by different techniques showed that the culture-independent method enabled the detection of ascomycetous and basidiomycetous fungi not found by culturing. The molecular method failed to detect members of the genera Penicillium and Cladosporium that possess small-sized spores known to have a high resistance to environmental changes.

Penicillium aurantiogriseum Dierckx 1901: Producer of Diketopiperazine Alkaloids (Roquefortine and 3,12-Dihydroroquefortine), Isolated from Permafrost

Secondary metabolites of three strains of Penicillium aurantiogriseumisolated from permafrost sediments were identified. It was found that these fungi synthesized the diketopiperazine alkaloids roquefortine and 3,12-dihydroroquefortine. The strain VKM FW-766 synthesized alkaloids in the course of certain growth-related processes. When the strain was grown on a mineral medium, the time courses of the roquefortine and 3,12-dihydroroquefortine concentrations were characterized by biphasic curves.

Synthesis of α-cyclopiazonic acid by fungi of the genus Aspergillus

The presence of α-cyclopiazonic acid has been studied among metabolites of Aspergillus fungi. The study was performed with 138 cultures of 13 species obtained from the All-Russia Collection of Microorganisms and the collection of our institute. α-Cyclopiazonic acid was most frequently encountered among the metabolites of the section Flavi (the ability to synthesize α-cyclopiazonic acid was expressed in 61% of the strains of A. flavus, 83% of the strains of A. oryzae, and all strains of A. tamarii). This expression index for A. versicolor was less than 5%. We showed for the first time that α-cyclopiazonic acid is produced by A. fumigatus and A. phoenicis (expression in 30% of the strains of either species).

Mycelial fungi in cryopegs

Mycelial fungi from cryopegs (tundra, Kolyma lowland, Russia) have been studied. The use of media with different amounts of salt and cultivation at 4 and 25 °C allowed us to isolate filamentous fungi assigned to 11 species. The micromycetes of genus Geomyces were found most often. The total amount of fungi reached 1–4×10 2 CFU ml −1 of water. The extreme conditions of the cryopegs – the high salinity of the water (150–200 g l −1 ) and the constant low temperatures (average annual temperature is from −9 to −11 °C) – might serve as a model for the conditions of interplanetary environments.

The structure of micromycete complexes in permafrost and cryopegs of the arctic

A comparative study of the structure of micromycete complexes has been performed. The samples of micromycetes were taken by boring from unique habitats: cryopegs (lenses of non-freezing hypersaline water in ancient permafrost horizons) and permafrost Arctic sediments of different age enclosing these cryopegs. The possibility of characterizing the above habitats by the structure of specific complexes of microscopic fungi using qualitative and quantitative indices at extremely low numbers of these organisms was demonstrated.

Fungal diversity in the Antarctic active layer

Taxonomic diversity of fungi in the samples of the active layer of Antarctica was investigated using conventional microbiological techniques and metagenomic analysis of total DNA extracted from environmental samples. The list of Antarctic microscopic fungi was expanded, including detection of the species representing a portion of the fungal complex which is nonculturable or sterile on conventional nutrient media.

New producers of biologically active compounds—fungal strains of the genus Penicillium isolated from permafrost

Screening of producers of secondary metabolites was carried out among 25 fungal strains of Penicillium genus isolated from permafrost in Arctic and Antarctic regions and Kamchatka. Nearly 50% of the investigated strains synthesize biologically active substances of alkaloid nature: ergot alkaloids, diketopiperazinees, and quinoline derivatives. A large group of the identified metabolites belongs to mycotoxins. A strain of Penicillium waksmanii was found producing epoxyagroclavine-I and quinocitrinines. The main physiological and biochemical characteristics of this producer were investigated.

Exo-metabolites of mycelial fungi isolated in production premises of cheese-making and meat-processing plants

Data were obtained on the species composition of mycelial fungi isolated from the air of workrooms and production premises in cheese-making and meat-processing plants. The strains studied were shown to be capable of producing various low molecular weight compounds. Many of them are mycotoxins such as α-cyclopiazonic acid (CPA), mycophenolic acid (MPA), citrinin, cladosporin, roquefortine and ergot alkaloids. The profiles of the secondary metabolites were used to elucidate the species’ names of the isolated strains.