Biorefining palm oil agricultural refinery waste for added value rhamnolipid production via fermentation

Rhamnolipids (RL) production by Pseudomonas aeruginosa PAO1 is a potentially attractive route to add value to palm oil refinery agricultural by-products; palm fatty acid distillate (PFAD) and fatty acid methyl ester (FAME). The results showed maximum RL concentration of 3.4 and 2.5 g L−1 when using 10 g L−1 PFAD and FAME respectively; while using 20 g L−1 PFAD and FAME, the RL concentrations achieved were 3.2 and 3.1 g L−1, respectively. The predominant congener produced was identified as dirhamnolipid, Rha-Rha-C10-C10. The RL produced reduced surface tension to 29-32 mN m−1 with a CMC value of 19 mg L−1. A high emulsion index with kerosene, 40 % and sunflower oil, 46 % were measured. This work demonstrates the potential for the utilisation of palm oil refinery agricultural by-products, PFAD and FAME, as low cost and renewable substrates for RL production in integrated palm oil biorefinery systems.