Enhancing Enzymatic Rhamnolipid Synthesis: Comparative Analysis of Sustainable Energy Sources

Abstract

Carbohydrate fatty acid esters, known as glycolipids, particularly rhamnolipids, have garnered significant interest due to their biodegradability, nontoxicity, and versatile applications in various industries. Despite their advantages, challenges remain in mass production, including high costs and low efficiency. Enzymatic synthesis offers a promising solution but faces difficulties such as slow reaction rates and low yields. This study investigates sustainable techniques, including mechanochemistry and microwave and ultrasound assistance, to enhance the enzymatic synthesis of rhamnolipids. A comparative analysis was conducted, utilizing Pseudomonas stutzeri lipase for transesterification reactions between rhamnose and vinyl laurate. Mechanochemistry, performed in a planetary ball mill, demonstrated efficient rhamnolipid synthesis without the need for solvents (99% conversion in 2 h). Microwave-assisted reactions showed conversion rates similar to those of conventional heating, while ultrasound-assisted reactions significantly accelerated the reaction rate, achieving nearly complete conversion in 1 h. Additionally, the use of a biomass-derived solvent such as 2-methyltetrahydrofuran further enhanced reaction efficiency and allowed scale-up of the process and the reuse of the biosolvent. The integration of biocatalytic transformation with ultrasonic irradiation and 2-methyltetrahydrofuran presents a promising strategy for sustainable rhamnolipids production. This innovative approach offers enhanced reaction kinetics, reduced energy consumption, and improved environmental sustainability, paving the way for greener biosurfactant production processes.