Urban soil mycobiota and its potential danger for human health in the Subarctic

The quantitative and qualitative parameters of cultivable microfungi communities in urban soils of Subarctic (Apatity, Murmansk region, Russia) were evaluated. In total, 21 species belonging to 11 genera, 10 families, 7 orders, 5 classes, and 2 divisions were distinguished. We determined the proportion of allergenic, toxigenic, and opportunistic microfungi and their potential pathogenicity for humans based on extracellular enzyme activity. The number of microfungi in urban soils varied from 1×103 to 9×104 CFU g-1 and was lower than in the forest soil (background) except in the recreational zone. In urban soils, there was a decrease in species diversity compared to forest soil and a significant change in species diversity, as evidenced by the low value of the Sørensen index (28%). Fungi that pose a threat to human health made up to 85% of the total number of isolated species. The most dangerous genus in urban soil was Aspergillus. An increase in their shares and frequency of occurrence in urban soils compared to the background was found as well. We noted the appearance of dangerous fungi belonging to the RG2 group, an increase in the number of toxigenic (by 15%) microfungi in urban soils. According to the mycological risk index (Im = 6.7-8.4), urban soils were classified as dangerous in Apatity. Microfungal strains with higher extracellular activity of proteinase and phospholipase enzymes than in the background soil were isolated from urban soils. These species also had the ability to grow at human body temperature. Regular monitoring of allergenic, opportunistic and toxigenic fungi in urban soils allows us to assess their potential impact on residents of Northern regions and recommend minimizing contact with the soil and hard road surfaces. This is especially important for preschool children, in order to reduce the likelihood of interaction with opportunistic fungi.