Optimization and characterization of rhamnolipid production by Pseudomonas aeruginosa NY3 using waste frying oil as the sole carbon

Yield and cost are two major factors limiting the widespread use of rhamnolipids (RLs). In the present study, waste frying oil (WFO) was used as the sole carbon source to produce environmentally friendly RLs by Pseudomonas aeruginosa NY3. The Plackett-Burman design (PBD) and Box-Behnken design (BBD) methods were used to maximize the production yield of RL. The PBD results showed that the concentrations of NaNO3, Na2HPO4, and trace elements were the key factors affecting the yield of RL. Furthermore, the BBD results showed that at NaNO3, Na2HPO4, and trace elements concentrations were 4.95, 0.66, and 0.64 mL/L, respectively, the average RL yield reached 9.15 +/- 0.52 g/L, 1.58-fold higher than that observed before optimization. Fourier transform infrared spectroscopy (FTIR) and liquid chromatography-ion trap-time of flight mass spectrometry (LCMS-IT-TOF) were used to elucidate the diversity of RL congeners. The results showed that, after optimization, the RL congener diversity increased, and the major RL constituent was converted from di-RLs (64.04%) to mono-RLs (60.44%). These results suggested that the concentrations of the components contained in the culture medium of P. aeruginosa NY3 influenced not only the yield of RL, but also its congener distribution.

Automated summary

The study found that the concentrations of NaNO3, Na2HPO4, and trace elements were key factors affecting the production yield of rhamnolipids when using waste frying oil as the carbon source. After optimization, the diversity of rhamnolipid congeners increased, with the major constituent shifting from di-rhamnolipids to mono-rhamnolipids. These results suggest that the concentrations of components in the culture medium of Pseudomonas aeruginosa NY3 not only affect the yield of rhamnolipids, but also their congener distribution.