Bacterial consortium as a model for studying the response of the microbial community of the Verkhnekamsk salt mining region to combined pollution

The unique ecosystem of industrial development area of the Verkhnekamsk salt deposit (VSD) (Perm krai, Russia) is characterized by the combined effect of salinization and contamination by organic pollutants, including polycyclic aromatic hydrocarbons (PAH). The purpose of the present study was to examine the degradative potential in relation to naphthalene, as a model PAH, under different salinity of bacterial consortium SMB3, previously isolated from soil of the VSD region, as well as the effect of long-term exposure to high salinity on the taxonomic composition of the consortium. The consortium SMB3 was able to grow on naphthalene both in the presence of NaCl up to 90 g/L, and in its absence. With an increase in the concentration of NaCl to 90 g/L, the growth rate of the consortium decreased by 2.1 times (compared with that of the consortium in a salt-free medium), and the naphthalene utilization estimated after 72 hours of cultivation decreased by 22.9 times. As a result of long-term cultivation in a mineral medium with naphthalene in the presence of 70 g/L NaCl, moderately halophilic strains Halomonas sp. SMB31 and Salinicola socius SMB35 T , not using naphthalene as the sole source of carbon and energy, and naphthalene degraders �hodococcus spp. SMB37 and SMB38 were shown to preserve in the consortium, while strains Glutamicibacter sp. SMB32, Microbacterium sp. SMB33, ‘‘ Thalassospira permensis ’’ SMB34 T , not growing on naphthalene, were eliminated. Thus, using the model experiments with the bacterial consortium SMB3, it has been shown that the soil autochthonous microbocenosis in the VSD salt-mining area is able to degrade persistent toxic organic compounds in a wide range of salinity, and prolonged exposure to a high salt concentration leads to a decrease in species richness.