ИСТИНА

In contaminated soils within a micromycetes complex the depletion of species composition, the increase of eurytops’ part and the species which are not authentic to the zonal soil conditions, and also the raise of potentially pathogenic species occur. Humic substances (HS) are used as agents for remediation of contaminated soils. They are able to influence metabolic pathways of organic and nonorganic ecotoxicants and show usually mitigating effects. Influence of combinations heavy metals and humate on micromycetes poorly understood. The aim of this experimental work is to study the effect of copper and humic substances on the dynamics the fungal biodiversity. Mycobiota of the artificial soils with the addition of heavy metal (Cu) 264 and 528 mg/kg as well as 0.1 and 1.0 g/kg humate (potassium humate produced from peat) was investigated. In our experiments the presence of Cu and humate in the growth medium caused a significant change in the community composition of cultivated fungi. It was primarily indicated by low values of the Sørensen - Chekanovsky index in comparison with the control samples. The addition of Cu and humate in different degrees stimulated the growth of metal-resistant genera Aspergillus and Penicillum, dark-colored genera Chaetomium and Paraconiothyrium and potentially pathogenic Fusarium. At the same time the addition of any components resulted in the elimination of genus Pseudogymnoascus. Humate had a positive effect on species composition of micromycetes communities. It was shown in the decline of the part of potentially pathogenic fungi included in the list of Biosafety Levels BSL1 and BSL2 (http://www.absa.org/resriskgroup.html). In the case when lower metal concentration (264 mg/kg) and humate (0.1 and 1.0 g/kg) presented in growth medium the part of pathogenic fungi included in both levels decreased. However, in the samples with combined addition of higher metal concentrations (528 mg/kg) and humate in both concentrations was noted a slight increase in the proportion of fungi included in the list of BSL2. Thus, it was shown that copper leads to qualitative disturbances of a natural community of cultivated fungi, and an addition of humate able to mitigate these consequences to some degree, but not completely. Acknowledgements: This study is supported by Russian Foundation for Basic Research (12-04-01230a) and ISTC (Project # KR- 2092).