Melanin-containing micromycetes in soils and organic waste
V.A. Terekhova, E.V. Fedoseeva, V.D. Volkova, А.E. Ivanova, O.S. Yakimenko
Section: Population ecology
Melanin formation in fungi used to indicate chemical and radiation contamination of soils depends on the composition of the environment and nutritional conditions. The relevance of this study is due to the assessment of the indicator significance of melanin-containing fungi under different conditions. The structure of mycobiota was studied in technosoil samples from organic composted wastes and in natural soils differing in the content of heavy metals (HMs) and available sources of carbon nutrition (Corg.). The total number of micromycetes, diversity, and representation of melanin-containing fungi were assessed by inoculation method and using high-throughput genome sequencing. Both methods showed an increase in the number of colony-forming units (CFU) of melanin-containing fungi with an increase in the load of HMs
in samples of soddy-podzolic soils. However, the traditional inoculation method also revealed a noticeable effect of the content of Corg. on the increase in melanized forms in the formed mycobiota of soils with HMs. Thus, in slightly humus soil (Сorg. = 1.3%), the introduction of HMs led to an increase in the number of CFU for melanized forms by 38%, in highly humus soil (Сorg. = 3.9) only by 18%. The obtained data confirm the proposition that in substrates depleted of carbohydrate nutrition, melanin formation contributes to an increase in resistance to redox stress. In the techno-soil from composted waste, despite the significant content of HMs, in particular, cadmium, the proportion of melanized fungi
is small, which is probably due to the immaturity of fungal communities in the waste. A conclusion was made about the greater bioindicative informativeness of the microbiological inoculation method before expensive metagenomic sequencing, and the effectiveness of its use in environmental monitoring of soil pollution.