Enzymatic modification of microbial rhamnolipids for industrial application

IVANA MAGARIO; ANKE NEUMANN; FRANK LEITERMANN; OLIVER VIELHAUER; CHRISTOPH SYLDATK

Delft

Simposio; Biotrans 2005, 7th International Symposium on Biocatalysis and Biotransformations; 2005

Delft University of Technology

Rhamnolipids are biosurfactants being used e.g. as surface cleaning agents. They are produced by Pseudomonas sp. and, though there are different kinds of them, the most relevant have a bond of one or two units of L-(+)-rhamnopyranoside with a (R,R)-3-(3- hydroxydecanoyloxy)decanoic acid. Enzymatic modification of the mixture resulting from the production by Pseudomonas sp. is proposed in order to obtain a unique species with higher tensoactive properties as well as a starting material for further modification. The cleavage of a rhamnolipid molecule into one unit of L-(+)-rhamnose and rhamnolipid 1 is attempted by means of the L-rhamnosidase activity in the commercial naringinase. A further cleavage of rhamnolipid 1 into a second unit of L-(+)-rhamnose takes also place, however at much lower rate and should be  avoided for production of rhamnolipid 1. As a result, the same ratio of the interesting by-product L-(+)-rhamnose is also gained, which is starting material for the synthesis of flavor agents. Therefore, optimization of the biotransformation of rhamnolipid 3 into rhamnolipid 1 by soluble enzyme should be first accomplished. As the stability and recovery of the enzyme is a desirable factor for its industrial application, characterization of its thermal inactivation in dependency on the temperature, pH and enzyme concentration is assayed by means of optimal experimental design and response surface methodology. A quantitative characterization of the kinetic at a very carefully selected set of temperature and pH is then to be achieved.