ИСТИНА

A variety and ecology of microscopic fungi in various substrates (snow and ice, lakes, cryopeg, long-term frozen breeds) of extremely cold habitats, including Antarctica are actively studied. However, the mycobiota of bio-inert systems and it abundance in the genetic soil horizons on this continent are almost not investigated. The aim of our work is assessment of distribution of number of mycobiota in profiles of different Antarctic soils by the following methods: the luminescent microscopy, the culturing (on Czapek agar and glucose-peptone agar) and the fungal 18S rRNA gene quantitative real-time PCR (qPCR) assay. The soil samples under study were selected by Drs Mergelov N.S. and Lupachev A.V. while performing the 55–58-s Russian Antarctic expeditions in the neighborhood of the Progress Station (samples No.70-72 under cover of moss Bryum pseudotriquetrum) and Russkaya Station (profile LA55-RS-05, samples No. 1-2, representing the “stone pavement” with algo-bacterial mats; profile LA55-RS-01, samples No. 3-5, representing soils underneath lichens).The number of the cultivated micromycetes decreased down in soil profiles from underneath lichens [from 9.6*103 (depth 2-7cm) to 7.8*102 CFU/g of substrate (deeper than 31см)] and from “stone pavement” (from 1.4*103 (1-5cm) to 4.2*102 (5-17 cm) CFU/g of substrate). In the soil under mosses the maximum of this index corresponded not to the surface [5.6*103 CFU/g of substrate (0-1cm)], but to the subsurface horizon [8.9*104 CFU/g of substrate (1-1.5cm)], sharply decreasing in more deep layer [2.3*103 CFU/g of substrate (1.5-2 cm)].Fungal biomass reached approximately identical values in all horizons of the soil under lichens (140 mgC/g of substrate) and in a “stone pavement” (100 mgC/g of substrate). Biomass of fungi was the least (550 mgC/g of substrate) in the surface (0-1cm) and deepest layer (1.5-2cm) in soil under the moss cover, but was the greatest (723 mgC/g of substrate) in the subsurface horizon (1-1.5cm).The number of copies of the gene 18S of rRNA of fungi for the soil underneath lichens and the "stone pavement" was reducing with depth. The tendency is more critical for the former type of soil [from 27*108 (1-5cm) to 5*108 (5-17cm) copies of the gene], while for the latter type of soil it is more smooth varying from 30*108 (2-7 cm) to 23*108 copies (deeper than 31cm)]. The reverse tendency was constituted in the profile under the moss: this indicator authentically increased from the top horizon to sublayers [from 6.1*107 (0-1cm) to 12*108 copies of the gene (2-3cm)]. Thus, distribution of mycobiota in profiles of different types of soils of Antarctica have been analyzed by the classical and molecular methods. It has been stated that there are types of soil in which the quantity of fungi is maximal not in the surface horizons but in the deep layers.