Degradation of Oil and Petroleum Products by Biocompositions Based on Humic Acids of Peats and Oil-Degrading Microorganisms

Abstract— The literature on the use of humic acids (HAs) in ecoadaptive technologies, as well as of biological and biotechnological methods of remediation of environmental media from oil pollution was surveyed, and the research results on development of biocompositions based on humic acids of peats and oil-degrading microorganisms of the genus Rhodococcus for the inactivation of oil and petroleum products in soil and aquatic environments under various abiotic conditions were summarized. Biocompositions exhibit enhanced dispersing, solubilizing, stabilizing, and biodegrading abilities with respect to oil and petroleum products in fresh and salt water and at low temperatures. The prospects of the combined use of oil-degrading bacteria and humic acids in the biocompositions as a biotechnological direction in the development of effective biopreparations for decomposition of petroleum hydrocarbons were demonstrated. Differences in the inactivating abilities of the biocompositions with respect to oil and petroleum products are associated with those in the ability of strains of microorganisms to form a biofilm on the surface of humic acids. In aquatic environments, the most versatile biocompositions exhibiting maximal biodegrading abilities are HAs (sphagnum high-moor peat) + Rh. erythropolis S67, HAs (reed fen peat) + Rh. erythropolis S67, and HAs (sphagnum high-moor peat) + Rh. erythropolis X5. The stabilizing ability of the biocompositions is determined by the origin of humic acids, being independent of the selected bacterial strain. High biodegradability of the biocompositions is due to the synergism of the action of the oil-degrading bacteria and humic acids under the conditions of oil pollution. Specifically, microorganisms oxidize hydrocarbon compounds, which they dissolve or emulsify, through release of biosurfactants, and humic acids, acting as a matrix for the biofilm formation, facilitate spontaneous adsorption of the microorganisms of the genus Rhodococcus at the oil–water interface.