Molecular Analysis of the Hydrolytic Component of Petroleum-Contaminated Soils and of Soils Remediated with Chitin

Molecular genetic techniques (FISH and metagenomic analysis) were used to investigate prokaryotic complexes in native soils (gray forest soil and urbostratozema typical), soils contaminated by petroleum products (gasoline or diesel fuel), and soils subject to remediation by addition of a nitrogen-containing polysaccharide biopolymer chitin. The share of metabolically active prokaryotic cells in the hydrolytic complex of soil microcosms was determined, as well as their biomass and biodiversity. Compared to the control, in the pollutant-containing experimental microcosms, a decrease in the share of metabolically active prokaryotic cells was observed, as well as changes of the hydrolytic complex structure, such as an increase in the share of the phylum Actinobacteria (specifically of the genera Galiella and Nocardioides in the samples contaminated with gasoline and diesel fuel, respectively). Supplementing the hydrocarbon-contaminated system the biopolymer chitin resulted in processing of mixed-minerals with an increase in the number of layers of the smectite type and, as a result, in formation of aggregates and improved aeration. An increase in the number of metabolically active prokaryotic cells and decreased diversity of the soil prokaryotic complex were observed, which were probably associated with the development of a selective group of the hydrolytic complex of chitin-degrading microorganisms.