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

Abstract

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.