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Number of results: 4
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Abstract

Saprotrophic filamentous microfungi were isolated by means of the soil dilution method from soil samples collected from four locations in the Bellsund region of Spitsbergen (77°33’N, 14°31’E) representing the following forms of surface micro-relief: an old stormbank, a sorted circle, a frost fissure between tundra polygons, and the central part of a tundra polygon. The fungal isolates were identified and screened for their ability to grow at low temperatures. The oligotrophy of psychrophilic and psychrotrophic strains was then determined as the ability of growth on silica gel without a C source added. Differences in some physico-chemical properties were found between the soils sampled from the four sites. A total of 89 taxa from 17 genera were isolated. Most of the isolates were species of Mortierella, Penicillium, Chrysosporium and Phialophora, and half of them were psychrophiles. Fungal communities isolated from a frost fissure between tundra polygons (site 3) and from the central part of a tundra polygon (site 4) were dominated by psychrophiles but those isolated from an old stormbank (site 1) and a sorted circle (site 2) were predominantly psychrotrophic. Oligopsychrophilic taxa accounted for 27% and oligopsychrotrophic for 20% of all the isolated taxa but only from 0.7% to 11.7% and from 1.2% to 6.3% of the total number of cfu (colony forming unit) isolated from an individual site, respectively. The results of the present study suggest that the abundance of fungi in Arctic soil is mostly affected by the content of organic matter in the A horizon and the plant cover, but other factors, such as the stage of soil development and the micro-relief of the surface, are more important for species richness of fungal communities.

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Authors and Affiliations

Ewa Kurek
Teresa Korniłłowicz-Kowalska
Anna Słomka
Jerzy Melke
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Abstract

Duringthe evolution organisms are subjected to the continuous impact of environmental factors. In recent years an increasing number of studies have focused on the physicochemical limits of lifeon Earthsuch as temperature, pressure, drought, salt content, pH, heavy metals, etc. Extreme environmental conditions disrupt the most important interactions that support the function and structure of biomolecules.Forthis reason,organisms inhabiting extreme habitats have recently become of particularlygreat interest. Although filamentous fungi are an important partof the polar ecosystem, information about their distribution and diversity, as well as their adaptation mechanisms, is insufficient. In the present study,the fungal strain Penicillium griseofulvum isolated from an Antarctic soil sample was used as a study model. The fungal cellular response against short term exposure to low temperature was observed. Our results clearly showed that short-term low temperature exposure caused oxidative stress in fungal cells and resulted in enhanced level of oxidative damaged proteins, accumulation of reserve carbohydrates and increased activity of the antioxidant enzyme defence. Ultrastructural changes in cell morphology wereanalysed. Different pattern of cell pathology provoked by the application of two stress temperatures was detected. Overall, this study aimed to observe the survival strategy of filamentous fungi in extremely cold habitats, and to acquire new knowledge about the relationship between low temperature and oxidative stress.
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Authors and Affiliations

Ekaterina Ts. Krumova
1
Ekaterina K. Koeva
1
Stoyanka R. Stoitsova
1
Tsvetelina S. Paunova-Krasteva
1
Galina D. Stoyancheva
1
Maria B. Angelova
1

  1. The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, 26, Acad. G. Bonchev str., 1113 Sofia, Bulgaria
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Abstract

Proteases play a key role in cell defense mechanisms to cold-induced oxidative stress. Data on the relationship between cold stress, growth phase, and temperature preferences of the fungal strains isolated from different habitats are very scarce. Here, we report changes in the intra- and extracellular protease activity of three fungal Penicillium strains (two Antarctic and one temperate) under transient temperature downshift during exponential- and stationary growth phases. The results indicated enhanced enzyme levels in both growth phases depending on the degree of stress and strain thermal class. In order to explain the obtained data, we compared them with our previous results on the protein carbonyl content, accumulation of oxidative-stress biomarkers, and antioxidant enzyme defense in the same three fungal strains. The cell response was affected by the temperature preference of the strain, but not by the climatic distance between the locations of isolation.
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Authors and Affiliations

Jeny Miteva-Staleva
1
ORCID: ORCID
Ekaterina Krumova
1
ORCID: ORCID
Boryana Spasova
1
ORCID: ORCID
Maria Angelova
1
ORCID: ORCID

  1. Department of Mycology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev str. 26, 1113 Sofia, Bulgaria

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