Ramnolipids application of Pseudomonas sp. Y3-B1A to improve the hydrocarbons biodegradation at different scales

Abstract

The accumulation of crude oil and its derivatives in soils is a serious environmental problem. Bioremediation is a widely studied and applied remediation technology for polluted ecosystems whose efficiency may be limited by the low solubility and toxicity of pollutants. The use of bio-surfactants stimulates the solubilization of hydrophobic molecules and increases bioavailability. In this work, the influence of rhamnolipids produced by Pseudomonas sp. Y3-B1A on the degradation of hydrocarbons at different scales was evaluated, determining also the toxicity of these molecules. In the laboratory, the degradation in a liquid medium supplemented with crude oil and incubated for 28 days was evaluated. The use of rhamnolipids increased the degradation rate of total petroleum hydrocarbons (HTP) by 61.7 % with respect to the treatment in which it was not added. In the microcosms and soil plots, the degradation of HTP, oils and grease (OG), saturated, aromatic, resins and asphaltenes compounds at 30 days was calculated. Nitrogen and phosphorus concentrations, and microbial growth were also determined. The application of rhamnolipids in the microcosms increased the degradation of HTP, saturated and aromatic compounds by more than 40 %. The increase in the degradation of HTP and aromatic compounds in soil plots was from 33 to 34 %, while for OG it reached a value of 86.5 %. The application of rhamnolipids increases the biodegradation of hydrocarbons without causing toxic effects to the ecosystem.