Rhamnolipids: Production, Performance, and Application

A circular bioeconomy requires the use of renewable resources to produce high-value specialty chemicals or pharmaceuticals, and also fine and bulk chemicals. Here, the surfactant market represents an ideal test case, because surfactants can cover diverse product classes ranging from fine to bulk chemicals and thus including large differences in purity and price. Biosurfactants produced by microbes from renewable resources are discussed for decades, and recently, sophorolipids arrived in the market, produced by fermentation of high-performing production strains and combined with simple product purification thus reaching low product prices. Here, we review the current status of rhamnolipid research and applications. Molecular diversity of rhamnolipids and biochemical pathways involved in their synthesis are presented, and physicochemical parameters governing emulsification, foaming, and other properties of rhamnolipids are summarized, followed by applications in many different industries including the agro and pharma industry. We finish with a patent survey that covers rhamnolipid production and potential applications of these biosurfactants. We also tried to identify knowledge gaps that might limit a more rapid establishment of rhamnolipids in the markets.