PARENT SESSION
45 - Radioecology
8:00 AM to 6:30 PM, Tuesday, 14 May 2002
Exhibition Area

(45-07) Biological Activity Of Fungi Which Develop In Conditions Of High Radioactive Loading .

Zhdanova, Nelli^*,1, Zakharchenko, Valentina¹, Rhedchitz, Tamara¹, Vember, Valeria¹, Blazheevskaya, Yuliya¹, Gerzabek, Martin², ¹ Institute of Microbiology and Virology, Kyiv, Ukraine² University of Agricultural Sciences Vienna, Vienna, Austria

ABSTRACT- During 15 years mycobiota in soil and forest litter of the 10-km limits zone and premises of 4-th block Chernobyl NPP were monitored. The collection of extremophilic fungi (more than 2000 cultures of 180 species of 92 genera) was created as result of this monitoring and was basis for the following investigations. Ecological analysis of each of the three econiches was realized. The frequency of each species, mean of predominance and biodiversity coefficients, percentage of contents of melanin-containing and indicated species in mycobiota were investigated. The study of the biological activity of such fungi was performed taking into account the specificity of their ecotope. The method of determination of fungal directional growth to the source of ionizing irradiation of low intensity (positive radiotropism feature) was established. This feature was investigated with fungal strains isolated from radioactive substrates of 10-km zone of ChNPP. At present we tested 143 strains of 37 species of 21 genera. Among them 26.5 % had this feature. The capacity of such fungi to overgrow and dissolve hot particles in time and to absorb radionuclides ¹³⁷Cs, ⁹⁰Sr , ¹⁵⁴Eu and others was quantified. As integral index of the biological activity of dominating extremophilic fungi in these econiches we used the character of their radial growth on optimal and starving solid mediums, hyphal growth unit (HGU) and intensity of colonization of substratum.. Two types of radioactive substrates colonization by fungi were identified. The first of them is characterized by slow radial growth and a low mean of HGU that leads to formation of small conidia and weak developing on the substratum. However, their capacity to form big number of conidia provides good substrate colonization. The second type of species is characterized by a significant radial growth rate and a corresponding high mean of HGU that leads to intensive colonization of substratum owing to quick mycelial growth. As a rule such species were characterized by scanty formation of conidia or its absence.

Key words: monitoring, strategies, radiotropism, extremophiles