[The effect of low radiation doses on the growth of Aspergillus versicolor and Paecilomyces lilacinus].

Peculiarities of growth of the strains of two species of microscopic fungi Aspergillus versicolor and Paecilomyces lilacinus were analyzed under exposure to chronic irradiation. It was shown that the rate of radial growth increased nonuniformly in the range of doses from 0 to 250 mGy but with maximums at a certain dose of radiation. It was shown that the absorbed dose of radiation to 2 Gy did not influence the survival of investigated strains in comparison with the control ones without irradiation. It was shown that the doses of irradiation to 2 Gy (at capacity exposure dose 0.955 microC/kg) are small for these species of microscopic fungi.

[Extremophilic microorganisms: biochemical adaptation and biotechnological application (review)].

The analysis of modern data on biochemical adaptation of microorganisms for living in extreme conditions is presented in this review. Special attention has been paid to the analysis of adaptive responses of microorganisms to the conditions of increased radiation at the molecular and cellular levels. The data on the practical application of extremophils and extremoenzymes, synthesized by them, biologically active substances, biopolymers and so on, have been systematized.

[Development of radioadaptive properties for microscopic fungi, long time located on terrains with a heightened background radiation after emergency on Chernobyl NPP].

In 7 species of micromycetes which were isolated from radioactive contaminated areas of Chernobyl NPP zone under exposure of two artificial sources: y-low energy (121Sn) and radiation mix type gamma + beta (137Cs). Two new earlier unknown radioadaptive properties for fungi--radiotropism and radiostimulation were established. The strains, which were isolated from clean areas, did not have such features. All investigated strains, which have shown positive radiotropism at the same time, have shown stimulation of conidia germination and of length of the emergent hyphum under exposure to one of sources of radiation. It was shown that micro fungi having radioadaptive properties, the adaptive response to high (100-1000 Gy) ionizing radiation doses was found that is evidence of that these strains have high radio resistance level. Nevertheless fungal strains have shown varied response to presence of ionizing radiation depending on its type and absorbed dose.

[The effect of gamma irradiation on the physiological-biochemical properties of strains of Cladosporium cladosporioides (Fres.) de Vries differing by the trait of radiotropism]. / Vliianie gamma-oblucheniia na fiziologo-biokhimicheskie svoistva shtammov Cladosporium cladosporioides (Fres.) de Vries, razlichaiushchikhsia po priznaku radiotropizma.

The influence of the low-intensity gamma-irradiation on the process of lipid peroxidation and the activities of the antioxidant glutathione-dependent system (catalase, glutathione-transferase) has been investigated in a number of Cladosporium cladosporioides (Fres.) de Vries strains. The dark-pigmented strains isolated from the habitats with different degree of radionuclide contamination, and the nonpigmented alb-mutant of the same species have been used in our work. The studied properties have been analyzed with the respect of the radiotropism property and of the presence of melanin pigment in the cell wall of these strains. The lipid perioxidation level under the effect of the low-intensity gamma-irradiation was greatly increased in Cladosporium cladosporioides 396 strain only. This strain was isolated from the radiation-pure soil. Catalase activity in a number of the studies strains correlated neither with their pigmentation, nor with the property of positive radiotropism. The correlation between the strain pigmentation and activity of glutathione transferase has been found.

[The protein-synthesizing activity of a number of strains of Cladosporium cladosporioides (Fres.) de Vries grown under conditions of continuous low-intensity gamma irradiation]. / Beloksinteziruiushchaia aktivnost' riada shtammov Cladosporium cladosporioides (Fres.) de Vries, vyrashchennykh v usloviiakh nepreryvnogo gamma-oblucheniia maloi intensivnosti.

Phenomena of melanization of radioactively polluted soils, due to prevalence of melanin-containing species and positive radiotropism of some micromycetes have been found during monitoring of mycobiota of the 30-km alienation zone of the Chernobyl NPP for 10 years. To elucidate the contribution of the melanin system to the cell protection against irradiation, the influence of gamma-irradiation on the activity of protein synthesis in four Cladosporium cladosporioides (Fres.) de Vries strains has been investigated. Two strains isolated from radioactively polluted substrates were characterised by the presence of positive radiotropism. Laboratory strain 396 and its alb-mutant (with blocked melanin synthesis), did not possess this feature. The protein synthesizing activity was assayed by incorporation of 14C-leucine in the protein fraction of mycelium, grown during 7 days under continuous gamma-irradiation of low intensity and without it. The protein synthesis was activated in the radioactively treated mycelium of dark-pigmented C. cladosporioides strains and it was suppressed in similarly treated mycelium of alb-mutant of C. cladosporioides. The rate of 14C-leucine incorporation into biomass of investigated strains correlated with positive radiotropism. The dependence between protein synthesis intensity and the availability of melanin protection system in micromycetes is assumed.

[Biosynthesis of 14C-macrocyclic trichothecenes]. / Biosintez 14C-makrotsiklicheskikh trikhotetsenov.

Possibility of producing (14C)-macrocyclic trichothecenes (MCTC) with high specific activity was studied. (1-14C)-glucose, (2-14C)-acetate and (2-14C)-mevalonate were used as precursors. The best results were obtained when labeled acetate was introduced into the medium at the end of the logarithmic growth stage of Dendrodochium toxicum 5800, a fungus-producer. Individual (14C)-MCTC with high specific activity are obtained: verrucarine A-158.1 microC/mM, rhoridine A-167.4 microC/mM; rhoridine H-161.9 microC/mM.