The production of high-value compounds by microbial bioconversion of inexpensive renewable substrates is a major goal in bioeconomy. Biosurfactants exemplify such substances that can serve as bio-based alternatives to surfactants produced from petroleum feedstock. The composition and properties of biosurfactants are limited by the respective metabolic potential of the natural production strains. In the tripartite project VariSurf, genetic engineering and artificial medium supplementation were used to expand the natural variation of glycolipids from a bacterial and a fungal microorganism for screening of their industrial applications. The main goals achieved in the project are: (i) Genetic modification of the rhamnolipid producing bacterium Burkholderia glumae and the fungus Ustilago maydis, a producer of cellobiose and mannosylerythritol glycolipids, towards production of a large variety of different glycolipids; (ii) optimization of biosurfactant production based on renewable resources for both production strains; here, the uncoupling of ustilagic acid production in U. maydis from nitrogen limitation resulted not only in shortened process time, but, unexpectedly, in the formation of novel glycolipid species; and (iii) parallel development of process strategies on small scale and upscaling of biosurfactant production processes for both organisms to achieve glycolipid yields that are sufficient for initial application tests by industrial partners. It was found that media composition influenced glycolipid composition and, furthermore, a novel highly effective strategy to purify mannosylerythritol lipids was established.
Conclusively, VariSurf extended the natural repertoire of biosurfactants produced by the chosen strains by combining genetic engineering of the respective pathways and media variation. Successful strategies for glycolipid production with B. glumae and U. maydis were developed and samples of the novel glycolipid compositions were forwarded to industrial partners for evaluation of properties and application potential.
Participating Core Groups
Dr. Stephan Thies, Institut für Molekulare Enzymtechnologie (IMET) , Heinrich-Heine-Universität Düsseldorf
Forschungszentrum Jülich, Geb. 15.8, Stetternicher Forst
Tel: +49 2461 613790
Prof. Dr. Karl-Erich Jaeger, Dr. Stephan Thies, Institute of Molecular Enzyme Technology, HHU Düsseldorf and IBG-1, Forschungszentrum Jülich
Prof. Dr. Michael Feldbrügge, Dr. Kerstin Schipper, Jörn Aschenbroich, Institute for Microbiology, HHU Düsseldorf
Prof. Dr. Jochen Büchs, Dr. Tino Schlepuetz und Max Schelden, AVT-Biochemical Engineering, RWTH Aachen University
VariSurf is part of the NRW-Strategieprojekt BioSC and thus funded by the Ministry of Innovation, Science and Research of the German State of North Rhine-Westphalia.