Simultaneous Production of Lipopeptide and Rhamnolipid Biosurfactants by Pseudomonas aeruginosa: A Promising Blend for Biosurfactant-Enhanced Bioremediation.

Oil contamination is a significant environmental issue worldwide, and in the last decades, bioremediation has emerged as a preferred strategy to address this challenge. However, the hydrophobic nature of oil and its limited bioavailability affect its biodegradation by the soil microbiota. To mitigate these limitations, surfactant use has been proposed to enhance oil bioremediation. Nowadays, there is a growing interest in reducing the carbon footprint, and the use of biosurfactants instead of synthetic ones contributes to this global objective. In this study, surfactant-producing bacteria were isolated from a polluted urban stream in Buenos Aires Province, Argentina, to obtain cell-free biosurfactant extracts for use as additives in surfactant-enhanced remediation (SER) protocols in diesel-contaminated microcosms. Out of five isolates, the surfactant extracts of two Pseudomonas aeruginosa strains were selected. One of them showed a significant improvement in diesel degradation compared with the controls. Remarkably, this extract was composed of a blend of rhamnolipids and lipopeptides whose presence was confirmed by analytical and bioinformatics evidence. This is the first work documenting the co-production of both kinds of surfactants by a P. aeruginosa strain and its potential for application in surfactant-enhanced bioremediation strategies.