Cost-Effective rhamnolipids production from corn Bran and their application in essential oil extraction.

Surfactants are widely used across industrial and environmental applications but their extensive discharge into aquatic environments raises ecological concerns. Biosurfactants, particularly rhamnolipids (RL) produced by Pseudomonas aeruginosa, represent a sustainable alternative due to their low toxicity, high biodegradability, and superior surface-active properties. Despite these advantages, high production costs remain a major barrier to large-scale implementation. In this study, RL were produced under submerged cultivation using glycerol, soybean oil, and corn bran (CB), a low-cost multifunctional agro-industrial substrate that simultaneously provided nutrients and structural support, resulting in an RL titer of 35 g/L. The produced RL consisted predominantly of di-rhamnolipid congeners (96.8%), which are associated with enhanced surface activity and commercial applicability. To further valorize the produced biosurfactant, RL-assisted steam distillation was evaluated as a novel strategy to enhance essential oil extraction. The application of RL increased essential oil recovery by 43%, demonstrating its effectiveness as a process booster. This combined strategy highlights the potential of CB-based RL production and its application in greener, more energy-efficient extraction technologies.