Characterization, production optimization and ecotoxicity of a lipopeptide biosurfactant by Pseudomonas citronellolis using oily wastewater

Considering both fundamental principles and application perspectives, it is imperative to characterize biosurfactants (BSFs) for replacing their synthetic counterparts. In this study, a BSF produced by the Pseudomonas citronellolis 620 C bacterium, using oily wastewater, was identified as a lipopeptide based on ultraviolet spectroscopy, thin layer chromatography, high-pressure liquid chromatography and nuclear magnetic resonance spectroscopy. The latter detected the lactone ring at the 5.1–4.9 ppm region, suggesting it as a cyclic lipopeptide (CLP). Gas chromatography/mass spectrometry detected high percentage of C16:0, C18:0 fatty acids, and aliphatic amino acids. A novel CLP is here proposed. To reduce its bioprocess costs, different nitrogen (N)-sources were tested using oily wastewater as the main nutrient source. Ammonium sulfate was the best N-source for the bacterium, reaching BSF production of 556 mg/L, at 10/2 C/N ratio. The BSF ecotoxicity for Aliivibrio fischeri, expressed as effective concentration (EC), was 0.45 and 3.04 g/L as EC20 and EC50, respectively. For Daphnia magna, the EC50 at 24 h and 48 h were 0.980 and 0.936 g/L, respectively. The lipopetide had no estrogenic activity up to 8 g/L. These data make the novel lipopeptide suitable for agriculture, environmental restoration, as dispersant in waste(water) biodisposal and life sciences applications.