ABSTRACT
Up to now, microbial surfactants have not been generally successful in substituting for chemical surfactants. Their use has been restricted to specific applications. One reason for this situation is the higher cost for synthesis and downstream processing. The prerequisites for a more competitive production of biosurfactants are [1]: 1. Highly active compounds with specific properties for particular applications 2. Cheap substrates 3. Cheap production processes (biosynthesis and downstream processing) 4. High biosurfactant yields
Rhamnolipids (RL) are surfactants that certainly meet the first demand. In the past years, several application areas have been described. Rhamnolipids were proposed as pesticides because of their antibacterial, mycoplasmacidal, and antiviral activities [2, 3], as concrete additives for higher strength and cement saving [4], and as a source of rhamnose [5]. They were also tested in bioremediation in particular in the clean-up of oil spills [6, 7], and in enhanced oil recovery [8, 9].
