Soil Microbiome in the Impact Zone of the Pechenganikel Plant Emissions (Murmansk Oblast)

The parameters of the microbiome in Albic Podzols are analyzed along the gradient of pollution (3, 16, 30, and 50 km) by Pechenganikel plant emissions (Murmansk oblast, Russia). The amount and structure of the prokaryotic and fungal biomass are assessed by luminescence microscopy; copy number of microbial ribosomal genes is determined by real-time PCR; and taxonomic diversity and abundance of culturable soil micromycetes are estimated. The copy number of the ribosomal genes of bacteria, archaea, and fungi increases close to the source of emissions as compared with remote sites. In all sites, bacteria display the highest copy number of ribosomal genes amounting to (3.21–12) × 10¹⁰ gene copies/g soil). As for fungi and archaea, the copy number varies in the range of (0.53–1.59) × 10¹⁰ and (0.55–11.41) × 10¹⁰ gene copies/g soil, respectively. The minimum copy number for all groups of microorganisms is observed at a distance of 50 km from the Pechenganikel plant and the maximum, in the range of 3–16 km from the source of emission. The abundance of prokaryotes varies in the range of (1.04–8.6) × 10⁸ cells/g soil and their biomass, from 0.2 to 18.3 µg/g soil. The fungal biomass changes from 122 to 572 µg/g soil. A significant decrease in the biomass of all groups of microorganisms is recorded near the plant. The fungal mycelium and spores in all sites are mainly represented by small forms with a diameter of 2–3 µm. The length of the fungal mycelium varies from 51.2 m/g near the plant to 397 m/g at remote sites; however, any regular patterns along the pollution gradient are unobservable. The diversity of culturable soil micromycetes at the level of genera and higher taxa decreases along the pollution gradient of Pechenganikel emissions. The structure of fungal communities changes from a polydominant type (background site) to a monodominant type (near the plant). Penicillium raistrickii is dominant in all sites. The fungi Aureobasidium pullulans and Trichoderma viride are dominant at a distance of 16 km from the pollution source and the dark-colored yeast Torula lucifuga, at a distance of 3 km. As for the background site, representatives of the orders Mucorales and Umbelopsidales are prevalent there.