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Polycyclic aromatic hydrocarbons (PAHs) are chemically recalcitrant carcinogenic and mutagenic compounds with primarily anthropogenic origin. The investigation of the effects of emissions from energy enterprises on soil microbiomes is of a high priority for modern soil science. In this study, metagenomic profiling of technogenic contaminated soils was carried out based on bioinformatic analysis of shotgun metagenome data with PAH-degrading genes identification. The use of prokaryotic consortia has been often used as one of the bio-remediation approaches to degrade PAHs with different molecular weight. Since the process of PAH degradation predominantly includes non-culturable or yet-to-be cultured species, metagenomic approaches are highly recommended for studying the composition and metabolic abilities of microbial communities. In this study, whole metagenome shotgun sequencing of DNA from two soils with varying PAH levels was performed. In the control site, the total content of 12 priority PAHs was 262 µg kg−1. The background soil levels in the polluted site for PAHs with 3 or more rings exceeded this, at 800 µg kg−1. The abundance of genes and taxa associated with PAH degradation in these two sites were estimated. Despite differences in PAH concentrations up to 1200 µg kg−1, individual and operon-organized PAH degradation genes were almost equally abundant and diverse in pristine and highly contaminated areas. The most numerous taxa in both spots were actinobacteria from Terrabacteria group. In addition to well-known PAH degraders such as Gordonia and Rhodococcus, genes corresponding to the PAH degradation were found in Azoarcus, Burkholderia and Variovorax. The data shows non-specificity and multifunctionality of metabolic pathways encoded in the genes of PAH-degrading microorganisms.

Tri-n-butyl phosphate (TBP) is widely used as an extractant in many technological processes. A thermodynamic model of the base extraction system water–tributyl phosphate is of great importance for industry. In this work a three-dimensional shape of the liquid phase Gibbs energy surface was modeled for the entire concentration range from pure water to pure TBP at temperatures from 273.15 K to more than 400 K and a pressure of 101325 Pa. Volumetric properties of the water–TBP solutions were measured at 288.15, 298.15, and 323.15 K. To obtain a thermodynamic description of the system of interest a new model of the excess Gibbs energy, the generalized local composition model (GLCM), was developed. Density of solutions, activity of components, enthalpy of mixing, and liquid–liquid equilibria in the water–TBP system were described by the GLCM expression.