Yeast Complexes in Urban Soils of Some Southern Cities of Russia (Krasnodar, Maykop, Simferopol, and Sochi)

Yeast number and species diversity in urban soils characterized by various intensities of anthropogenic impact in the southern cities of Russia (Krasnodar, Maykop, Simferopol, and Sochi) was investigated. The soils of botanical gardens and the reference soils in the vicinities of cities were used for comparison to reveal the degree of anthropogenic impact. The maximum yeast number was found in a layer of 0–20 cm in the urban soils of Sochi and Simferopol, where it was 5.7 ± 0.2 and 5.4 ± 0.01 log (CFU/g), respectively. The minimum number of yeasts, 2.0 ± 0.1 log (CFU/g), was characteristic of a 60–80-cm layer in the soils in the vicinities of all cities. The number of yeasts was shown to depend primarily on the depth and type of soil and to a lesser extent on location. A total of 20 yeast species were isolated from the studied soils: 10 ascomycetes and 10 basidiomycetes. All basidiomycete yeasts isolated from urban soils and control soils were typical representatives of pedobiont and epiphytic yeast complexes. In the soils of the major tourist cities of Sochi and Simferopol, a high relative abundance of ascomycete species Candida sake and Meyerozyma guilliermondii was found, which fundamentally distinguished the studied soils from the ones of Krasnodar and Maykop. The cities of Sochi and Simferopol are characterized by a higher anthropogenic load compared to Krasnodar and Maykop, which is associated not only with their high population, but also with a significant tourist load. Detection in urban soils of C. sake and M. guilliermondii which, according to some data, are clinically significant, was therefore consequential.